Add compatibility switch controlling parameter metadata and top-level validation

- #7413 part 1 of 2
- made all `ModelMetadataProvider` and `ObjectModelValidator`-specific code conditional
  - fortunately, `MvcOptions` easy to get; affected code is primarily `internal` or pub-`Internal`
  - remove unnecessary `ModelMetadataProvider` use in `ApiBehaviorApplicationModelProvider`
- run integration and functional tests with `CompatibilityVersion.Version_2_1`
  - functional test change depends on @javiercn's recent #7541 fix
  - remove test code now redundantly turning compatibility switches on

nits:
- correct spelling errors in `CompatibilitySwitch`
- take VS suggestions, mostly in test code
- rename methods in `ControllerBinderDelegateProviderTest` to match current API
- slightly refactor in `ApiBehaviorApplicationModelProvider`

src/Microsoft.AspNetCore.Mvc.ApiExplorer/DefaultApiDescriptionProvider.cs

@@ -24,10 +24,9 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
     /// </summary>
     public class DefaultApiDescriptionProvider : IApiDescriptionProvider
     {
-        private readonly IList<IInputFormatter> _inputFormatters;
+        private readonly MvcOptions _mvcOptions;
-        private readonly IList<IOutputFormatter> _outputFormatters;
-        private readonly IModelMetadataProvider _modelMetadataProvider;
         private readonly IInlineConstraintResolver _constraintResolver;
+        private readonly IModelMetadataProvider _modelMetadataProvider;
 
         /// <summary>
         /// Creates a new instance of <see cref="DefaultApiDescriptionProvider"/>.
@@ -41,8 +40,7 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
             IInlineConstraintResolver constraintResolver,
             IModelMetadataProvider modelMetadataProvider)
         {
-            _inputFormatters = optionsAccessor.Value.InputFormatters;
+            _mvcOptions = optionsAccessor.Value;
-            _outputFormatters = optionsAccessor.Value.OutputFormatters;
             _constraintResolver = constraintResolver;
             _modelMetadataProvider = modelMetadataProvider;
         }
@@ -164,7 +162,8 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
                     var visitor = new PseudoModelBindingVisitor(context, actionParameter);
 
                     ModelMetadata metadata = null;
-                    if (actionParameter is ControllerParameterDescriptor controllerParameterDescriptor &&
+                    if (_mvcOptions.AllowValidatingTopLevelNodes &&
+                        actionParameter is ControllerParameterDescriptor controllerParameterDescriptor &&
                         _modelMetadataProvider is ModelMetadataProvider provider)
                     {
                         // The default model metadata provider derives from ModelMetadataProvider
@@ -344,7 +343,7 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
             var results = new List<ApiRequestFormat>();
             foreach (var contentType in contentTypes)
             {
-                foreach (var formatter in _inputFormatters)
+                foreach (var formatter in _mvcOptions.InputFormatters)
                 {
                     if (formatter is IApiRequestFormatMetadataProvider requestFormatMetadataProvider)
                     {
@@ -422,7 +421,7 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
                 contentTypes.Add((string)null);
             }
 
-            var responseTypeMetadataProviders = _outputFormatters.OfType<IApiResponseTypeMetadataProvider>();
+            var responseTypeMetadataProviders = _mvcOptions.OutputFormatters.OfType<IApiResponseTypeMetadataProvider>();
 
             foreach (var objectType in objectTypes)
             {

src/Microsoft.AspNetCore.Mvc.Core/Infrastructure/CompatibilitySwitch.cs

@@ -17,7 +17,7 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
     // behaviors in a minor release.
     //
     // To make things better for future users, we also want to provide an easy way for applications to get
-    // access to the new behaviors. We make changes when they are improvments, and if we're changing something
+    // access to the new behaviors. We make changes when they are improvements, and if we're changing something
     // we've already shipped, it must add value for all of our users (eventually). To this end, new applications
     // created using the template are always opted in to the 'current' version.
     //
@@ -48,19 +48,19 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
     //
     /// <summary>
     /// Infrastructure supporting the implementation of <see cref="CompatibilityVersion"/>. This is an
-    /// implementation of <see cref="ICompatibilitySwitch"/> suitible for use with the <see cref="IOptions{T}"/>
+    /// implementation of <see cref="ICompatibilitySwitch"/> suitable for use with the <see cref="IOptions{T}"/>
     /// pattern. This is framework infrastructure and should not be used by application code.
     /// </summary>
-    /// <typeparam name="TValue">The type of value assoicated with the compatibility switch.</typeparam>
+    /// <typeparam name="TValue">The type of value associated with the compatibility switch.</typeparam>
     public class CompatibilitySwitch<TValue> : ICompatibilitySwitch where TValue : struct
     {
         private TValue _value;
 
         /// <summary>
-        /// Creates a new compatiblity switch with the provided name.
+        /// Creates a new compatibility switch with the provided name.
         /// </summary>
         /// <param name="name">
-        /// The compatiblity switch name. The name must match a property name on an options type.
+        /// The compatibility switch name. The name must match a property name on an options type.
         /// </param>
         public CompatibilitySwitch(string name)
             : this(name, default)
@@ -68,10 +68,10 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
         }
 
         /// <summary>
-        /// Creates a new compatiblity switch with the provided name and initial value.
+        /// Creates a new compatibility switch with the provided name and initial value.
         /// </summary>
         /// <param name="name">
-        /// The compatiblity switch name. The name must match a property name on an options type.
+        /// The compatibility switch name. The name must match a property name on an options type.
         /// </param>
         /// <param name="initialValue">
         /// The initial value to assign to the switch.

src/Microsoft.AspNetCore.Mvc.Core/Infrastructure/MvcOptionsConfigureCompatibilityOptions.cs

@@ -27,6 +27,7 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
                 {
                     values[nameof(MvcOptions.AllowCombiningAuthorizeFilters)] = true;
                     values[nameof(MvcOptions.AllowBindingHeaderValuesToNonStringModelTypes)] = true;
+                    values[nameof(MvcOptions.AllowValidatingTopLevelNodes)] = true;
                     values[nameof(MvcOptions.InputFormatterExceptionPolicy)] = InputFormatterExceptionPolicy.MalformedInputExceptions;
                     values[nameof(MvcOptions.SuppressBindingUndefinedValueToEnumType)] = true;
                 }

src/Microsoft.AspNetCore.Mvc.Core/Internal/ApiBehaviorApplicationModelProvider.cs

@@ -216,16 +216,13 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         {
             foreach (var parameter in actionModel.Parameters)
             {
-                if (parameter.BindingInfo != null &&
+                var bindingInfo = parameter.BindingInfo;
-                    parameter.BindingInfo.BinderModelName == null &&
+                if (bindingInfo?.BindingSource != null &&
-                    parameter.BindingInfo.BindingSource != null &&
+                    bindingInfo.BinderModelName == null &&
-                    !parameter.BindingInfo.BindingSource.IsGreedy)
+                    !bindingInfo.BindingSource.IsGreedy &&
+                    IsComplexTypeParameter(parameter))
                 {
-                    var metadata = GetParameterMetadata(parameter);
+                    parameter.BindingInfo.BinderModelName = string.Empty;
-                    if (metadata.IsComplexType)
-                    {
-                        parameter.BindingInfo.BinderModelName = string.Empty;
-                    }
                 }
             }
         }
@@ -233,25 +230,16 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         // Internal for unit testing.
         internal BindingSource InferBindingSourceForParameter(ParameterModel parameter)
         {
-            var parameterType = parameter.ParameterInfo.ParameterType;
             if (ParameterExistsInAllRoutes(parameter.Action, parameter.ParameterName))
             {
                 return BindingSource.Path;
             }
-            else
-            {
-                var parameterMetadata = GetParameterMetadata(parameter);
-                if (parameterMetadata != null)
-                {
-                    var bindingSource = parameterMetadata.IsComplexType ?
-                        BindingSource.Body :
-                        BindingSource.Query;
 
-                    return bindingSource;
+            var bindingSource = IsComplexTypeParameter(parameter) ?
-                }
+                BindingSource.Body :
-            }
+                BindingSource.Query;
 
-            return null;
+            return bindingSource;
         }
 
         private bool ParameterExistsInAllRoutes(ActionModel actionModel, string parameterName)
@@ -277,16 +265,12 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             return parameterExistsInSomeRoute;
         }
 
-        private ModelMetadata GetParameterMetadata(ParameterModel parameter)
+        private bool IsComplexTypeParameter(ParameterModel parameter)
         {
-            if (_modelMetadataProvider is ModelMetadataProvider modelMetadataProvider)
+            // No need for information from attributes on the parameter. Just use its type.
-            {
+            return _modelMetadataProvider
-                return modelMetadataProvider.GetMetadataForParameter(parameter.ParameterInfo);
+                .GetMetadataForType(parameter.ParameterInfo.ParameterType)
-            }
+                .IsComplexType;
-            else
-            {
-                return _modelMetadataProvider.GetMetadataForType(parameter.ParameterInfo.ParameterType);
-            }
         }
     }
 }

src/Microsoft.AspNetCore.Mvc.Core/Internal/ControllerActionInvokerCache.cs

@@ -10,6 +10,7 @@ using Microsoft.AspNetCore.Mvc.Filters;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
 using Microsoft.Extensions.Internal;
+using Microsoft.Extensions.Options;
 
 namespace Microsoft.AspNetCore.Mvc.Internal
 {
@@ -21,7 +22,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         private readonly IModelMetadataProvider _modelMetadataProvider;
         private readonly IFilterProvider[] _filterProviders;
         private readonly IControllerFactoryProvider _controllerFactoryProvider;
-
+        private readonly MvcOptions _mvcOptions;
         private volatile InnerCache _currentCache;
 
         public ControllerActionInvokerCache(
@@ -30,7 +31,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             IModelBinderFactory modelBinderFactory,
             IModelMetadataProvider modelMetadataProvider,
             IEnumerable<IFilterProvider> filterProviders,
-            IControllerFactoryProvider factoryProvider)
+            IControllerFactoryProvider factoryProvider,
+            IOptions<MvcOptions> mvcOptions)
         {
             _collectionProvider = collectionProvider;
             _parameterBinder = parameterBinder;
@@ -38,6 +40,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             _modelMetadataProvider = modelMetadataProvider;
             _filterProviders = filterProviders.OrderBy(item => item.Order).ToArray();
             _controllerFactoryProvider = factoryProvider;
+            _mvcOptions = mvcOptions.Value;
         }
 
         private InnerCache CurrentCache
@@ -82,7 +85,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     _parameterBinder,
                     _modelBinderFactory,
                     _modelMetadataProvider,
-                    actionDescriptor);
+                    actionDescriptor,
+                    _mvcOptions);
 
                 var actionMethodExecutor = ActionMethodExecutor.GetExecutor(objectMethodExecutor);
 

src/Microsoft.AspNetCore.Mvc.Core/Internal/ControllerBinderDelegateProvider.cs

@@ -16,13 +16,19 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             ParameterBinder parameterBinder,
             IModelBinderFactory modelBinderFactory,
             IModelMetadataProvider modelMetadataProvider,
-            ControllerActionDescriptor actionDescriptor)
+            ControllerActionDescriptor actionDescriptor,
+            MvcOptions mvcOptions)
         {
             if (parameterBinder == null)
             {
                 throw new ArgumentNullException(nameof(parameterBinder));
             }
 
+            if (modelBinderFactory == null)
+            {
+                throw new ArgumentNullException(nameof(modelBinderFactory));
+            }
+
             if (modelMetadataProvider == null)
             {
                 throw new ArgumentNullException(nameof(modelMetadataProvider));
@@ -33,7 +39,16 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 throw new ArgumentNullException(nameof(actionDescriptor));
             }
 
-            var parameterBindingInfo = GetParameterBindingInfo(modelBinderFactory, modelMetadataProvider, actionDescriptor);
+            if (mvcOptions == null)
+            {
+                throw new ArgumentNullException(nameof(mvcOptions));
+            }
+
+            var parameterBindingInfo = GetParameterBindingInfo(
+                modelBinderFactory,
+                modelMetadataProvider,
+                actionDescriptor,
+                mvcOptions);
             var propertyBindingInfo = GetPropertyBindingInfo(modelBinderFactory, modelMetadataProvider, actionDescriptor);
 
             if (parameterBindingInfo == null && propertyBindingInfo == null)
@@ -104,7 +119,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         private static BinderItem[] GetParameterBindingInfo(
             IModelBinderFactory modelBinderFactory,
             IModelMetadataProvider modelMetadataProvider,
-            ControllerActionDescriptor actionDescriptor)
+            ControllerActionDescriptor actionDescriptor,
+            MvcOptions mvcOptions)
         {
             var parameters = actionDescriptor.Parameters;
             if (parameters.Count == 0)
@@ -118,8 +134,9 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 var parameter = parameters[i];
 
                 ModelMetadata metadata;
-                if (modelMetadataProvider is ModelMetadataProvider modelMetadataProviderBase
+                if (mvcOptions.AllowValidatingTopLevelNodes &&
-                    && parameter is ControllerParameterDescriptor controllerParameterDescriptor)
+                    modelMetadataProvider is ModelMetadataProvider modelMetadataProviderBase &&
+                    parameter is ControllerParameterDescriptor controllerParameterDescriptor)
                 {
                     // The default model metadata provider derives from ModelMetadataProvider
                     // and can therefore supply information about attributes applied to parameters.

src/Microsoft.AspNetCore.Mvc.Core/ModelBinding/ObjectModelValidator.cs

@@ -20,7 +20,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
         /// <summary>
         /// Initializes a new instance of <see cref="ObjectModelValidator"/>.
         /// </summary>
-        /// <param name="modelMetadataProvider">The <see cref="ModelMetadataProvider"/>.</param>
+        /// <param name="modelMetadataProvider">The <see cref="IModelMetadataProvider"/>.</param>
         /// <param name="validatorProviders">The list of <see cref="IModelValidatorProvider"/>.</param>
         public ObjectModelValidator(
             IModelMetadataProvider modelMetadataProvider,

src/Microsoft.AspNetCore.Mvc.Core/ModelBinding/ParameterBinder.cs

@@ -8,6 +8,7 @@ using Microsoft.AspNetCore.Mvc.Internal;
 using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
 
 namespace Microsoft.AspNetCore.Mvc.ModelBinding
 {
@@ -18,23 +19,31 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
     {
         private readonly IModelMetadataProvider _modelMetadataProvider;
         private readonly IModelBinderFactory _modelBinderFactory;
+        private readonly MvcOptions _mvcOptions;
         private readonly IObjectModelValidator _objectModelValidator;
 
         /// <summary>
         /// <para>This constructor is obsolete and will be removed in a future version. The recommended alternative
-        /// is the overload that also takes an <see cref="ILoggerFactory"/>.</para>
+        /// is the overload that also takes a <see cref="MvcOptions"/> accessor and an <see cref="ILoggerFactory"/>.
+        /// </para>
         /// <para>Initializes a new instance of <see cref="ParameterBinder"/>.</para>
         /// </summary>
         /// <param name="modelMetadataProvider">The <see cref="IModelMetadataProvider"/>.</param>
         /// <param name="modelBinderFactory">The <see cref="IModelBinderFactory"/>.</param>
         /// <param name="validator">The <see cref="IObjectModelValidator"/>.</param>
         [Obsolete("This constructor is obsolete and will be removed in a future version. The recommended alternative"
-            + " is the overload that also takes an " + nameof(ILoggerFactory) + ".")]
+            + " is the overload that also takes a " + nameof(MvcOptions) + " accessor and an "
+            + nameof(ILoggerFactory) + " .")]
         public ParameterBinder(
             IModelMetadataProvider modelMetadataProvider,
             IModelBinderFactory modelBinderFactory,
             IObjectModelValidator validator)
-            : this(modelMetadataProvider, modelBinderFactory, validator, NullLoggerFactory.Instance)
+            : this(
+                  modelMetadataProvider,
+                  modelBinderFactory,
+                  validator,
+                  Options.Create(new MvcOptions()),
+                  NullLoggerFactory.Instance)
         {
         }
 
@@ -44,11 +53,13 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
         /// <param name="modelMetadataProvider">The <see cref="IModelMetadataProvider"/>.</param>
         /// <param name="modelBinderFactory">The <see cref="IModelBinderFactory"/>.</param>
         /// <param name="validator">The <see cref="IObjectModelValidator"/>.</param>
+        /// <param name="mvcOptions">The <see cref="MvcOptions"/> accessor.</param>
         /// <param name="loggerFactory">The <see cref="ILoggerFactory"/>.</param>
         public ParameterBinder(
             IModelMetadataProvider modelMetadataProvider,
             IModelBinderFactory modelBinderFactory,
             IObjectModelValidator validator,
+            IOptions<MvcOptions> mvcOptions,
             ILoggerFactory loggerFactory)
         {
             if (modelMetadataProvider == null)
@@ -66,6 +77,11 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 throw new ArgumentNullException(nameof(validator));
             }
 
+            if (mvcOptions == null)
+            {
+                throw new ArgumentNullException(nameof(mvcOptions));
+            }
+
             if (loggerFactory == null)
             {
                 throw new ArgumentNullException(nameof(loggerFactory));
@@ -74,6 +90,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             _modelMetadataProvider = modelMetadataProvider;
             _modelBinderFactory = modelBinderFactory;
             _objectModelValidator = validator;
+            _mvcOptions = mvcOptions.Value;
             Logger = loggerFactory.CreateLogger(GetType());
         }
 
@@ -224,8 +241,21 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
 
             var modelBindingResult = modelBindingContext.Result;
 
-            var baseObjectValidator = _objectModelValidator as ObjectModelValidator;
+            if (_mvcOptions.AllowValidatingTopLevelNodes &&
-            if (baseObjectValidator == null)
+                _objectModelValidator is ObjectModelValidator baseObjectValidator)
+            {
+                Logger.AttemptingToValidateParameterOrProperty(parameter, modelBindingContext);
+
+                EnforceBindRequiredAndValidate(
+                    baseObjectValidator,
+                    actionContext,
+                    metadata,
+                    modelBindingContext,
+                    modelBindingResult);
+
+                Logger.DoneAttemptingToValidateParameterOrProperty(parameter, modelBindingContext);
+            }
+            else
             {
                 // For legacy implementations (which directly implemented IObjectModelValidator), fall back to the
                 // back-compatibility logic. In this scenario, top-level validation attributes will be ignored like
@@ -239,19 +269,6 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                         modelBindingResult.Model);
                 }
             }
-            else
-            {
-                Logger.AttemptingToValidateParameterOrProperty(parameter, modelBindingContext);
-
-                EnforceBindRequiredAndValidate(
-                    baseObjectValidator,
-                    actionContext,
-                    metadata,
-                    modelBindingContext,
-                    modelBindingResult);
-
-                Logger.DoneAttemptingToValidateParameterOrProperty(parameter, modelBindingContext);
-            }
 
             return modelBindingResult;
         }

src/Microsoft.AspNetCore.Mvc.Core/MvcOptions.cs

@@ -27,6 +27,7 @@ namespace Microsoft.AspNetCore.Mvc
         // See CompatibilitySwitch.cs for guide on how to implement these.
         private readonly CompatibilitySwitch<bool> _allowBindingHeaderValuesToNonStringModelTypes;
         private readonly CompatibilitySwitch<bool> _allowCombiningAuthorizeFilters;
+        private readonly CompatibilitySwitch<bool> _allowValidatingTopLevelNodes;
         private readonly CompatibilitySwitch<InputFormatterExceptionPolicy> _inputFormatterExceptionPolicy;
         private readonly CompatibilitySwitch<bool> _suppressBindingUndefinedValueToEnumType;
         private readonly ICompatibilitySwitch[] _switches;
@@ -50,6 +51,7 @@ namespace Microsoft.AspNetCore.Mvc
 
             _allowCombiningAuthorizeFilters = new CompatibilitySwitch<bool>(nameof(AllowCombiningAuthorizeFilters));
             _allowBindingHeaderValuesToNonStringModelTypes = new CompatibilitySwitch<bool>(nameof(AllowBindingHeaderValuesToNonStringModelTypes));
+            _allowValidatingTopLevelNodes = new CompatibilitySwitch<bool>(nameof(AllowValidatingTopLevelNodes));
             _inputFormatterExceptionPolicy = new CompatibilitySwitch<InputFormatterExceptionPolicy>(nameof(InputFormatterExceptionPolicy), InputFormatterExceptionPolicy.AllExceptions);
             _suppressBindingUndefinedValueToEnumType = new CompatibilitySwitch<bool>(nameof(SuppressBindingUndefinedValueToEnumType));
 
@@ -57,6 +59,7 @@ namespace Microsoft.AspNetCore.Mvc
             {
                 _allowCombiningAuthorizeFilters,
                 _allowBindingHeaderValuesToNonStringModelTypes,
+                _allowValidatingTopLevelNodes,
                 _inputFormatterExceptionPolicy,
                 _suppressBindingUndefinedValueToEnumType,
             };
@@ -114,9 +117,9 @@ namespace Microsoft.AspNetCore.Mvc
 
         /// <summary>
         /// Gets or sets a value that determines if <see cref="HeaderModelBinder"/> should bind to types other than
-        /// <see cref="String"/> or a collection of <see cref="String"/>. If set to <c>true</c>,
+        /// <see cref="string"/> or a collection of <see cref="string"/>. If set to <c>true</c>,
-        /// <see cref="HeaderModelBinder"/> would bind to simple types (like <see cref="String"/>, <see cref="Int32"/>,
+        /// <see cref="HeaderModelBinder"/> would bind to simple types (like <see cref="string"/>, <see cref="int"/>,
-        /// <see cref="Enum"/>, <see cref="Boolean"/> etc.) or a collection of simple types. The default value of the
+        /// <see cref="Enum"/>, <see cref="bool"/> etc.) or a collection of simple types. The default value of the
         /// property is <c>false</c>.
         /// </summary>
         /// <remarks>
@@ -144,6 +147,41 @@ namespace Microsoft.AspNetCore.Mvc
             set => _allowBindingHeaderValuesToNonStringModelTypes.Value = value;
         }
 
+        /// <summary>
+        /// Gets or sets a value that determines if model bound action parameters, controller properties, page handler
+        /// parameters, or page model properties are validated (in addition to validating their elements or
+        /// properties). If set to <see langword="true"/>, <see cref="BindRequiredAttribute"/> and
+        /// <c>ValidationAttribute</c>s on these top-level nodes are checked. Otherwise, such attributes are ignored.
+        /// </summary>
+        /// <value>
+        /// The default value is <see langword="true"/> if the version is
+        /// <see cref="CompatibilityVersion.Version_2_1"/> or later; <see langword="false"/> otherwise.
+        /// </value>
+        /// <remarks>
+        /// <para>
+        /// This property is associated with a compatibility switch and can provide a different behavior depending on
+        /// the configured compatibility version for the application. See <see cref="CompatibilityVersion"/> for
+        /// guidance and examples of setting the application's compatibility version.
+        /// </para>
+        /// <para>
+        /// Configuring the desired value of the compatibility switch by calling this property's setter will take
+        /// precedence over the value implied by the application's <see cref="CompatibilityVersion"/>.
+        /// </para>
+        /// <para>
+        /// If the application's compatibility version is set to <see cref="CompatibilityVersion.Version_2_0"/> then
+        /// this setting will have the value <see langword="false"/> unless explicitly configured.
+        /// </para>
+        /// <para>
+        /// If the application's compatibility version is set to <see cref="CompatibilityVersion.Version_2_1"/> or
+        /// higher then this setting will have the value <see langword="true"/> unless explicitly configured.
+        /// </para>
+        /// </remarks>
+        public bool AllowValidatingTopLevelNodes
+        {
+            get => _allowValidatingTopLevelNodes.Value;
+            set => _allowValidatingTopLevelNodes.Value = value;
+        }
+
         /// <summary>
         /// Gets a Dictionary of CacheProfile Names, <see cref="CacheProfile"/> which are pre-defined settings for
         /// response caching.
@@ -204,7 +242,7 @@ namespace Microsoft.AspNetCore.Mvc
         public FormatterCollection<IInputFormatter> InputFormatters { get; }
 
         /// <summary>
-        /// Gets or sets an value indicating whether the model binding system will bind undefined values to 
+        /// Gets or sets a value indicating whether the model binding system will bind undefined values to
         /// enum types. The default value of the property is <c>false</c>.
         /// </summary>
         /// <remarks>

src/Microsoft.AspNetCore.Mvc.RazorPages/Internal/PageActionInvokerProvider.cs

@@ -6,7 +6,6 @@ using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
-using System.Threading.Tasks;
 using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Mvc.Filters;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
@@ -37,6 +36,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
         private readonly ParameterBinder _parameterBinder;
         private readonly IModelMetadataProvider _modelMetadataProvider;
         private readonly ITempDataDictionaryFactory _tempDataFactory;
+        private readonly MvcOptions _mvcOptions;
         private readonly HtmlHelperOptions _htmlHelperOptions;
         private readonly IPageHandlerMethodSelector _selector;
         private readonly RazorProjectFileSystem _razorFileSystem;
@@ -73,6 +73,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
             _parameterBinder = parameterBinder;
             _modelMetadataProvider = modelMetadataProvider;
             _tempDataFactory = tempDataFactory;
+            _mvcOptions = mvcOptions.Value;
             _htmlHelperOptions = htmlHelperOptions.Value;
             _selector = selector;
             _razorFileSystem = razorFileSystem;
@@ -261,7 +262,8 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
                     _modelMetadataProvider,
                     _modelBinderFactory,
                     actionDescriptor,
-                    actionDescriptor.HandlerMethods[i]);
+                    actionDescriptor.HandlerMethods[i],
+                    _mvcOptions);
             }
 
             return results;

src/Microsoft.AspNetCore.Mvc.RazorPages/Internal/PageBinderFactory.cs

@@ -90,7 +90,8 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
             IModelMetadataProvider modelMetadataProvider,
             IModelBinderFactory modelBinderFactory,
             CompiledPageActionDescriptor actionDescriptor,
-            HandlerMethodDescriptor handler)
+            HandlerMethodDescriptor handler,
+            MvcOptions mvcOptions)
         {
             if (handler.Parameters == null || handler.Parameters.Count == 0)
             {
@@ -103,7 +104,8 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
             {
                 var parameter = handler.Parameters[i];
                 ModelMetadata metadata;
-                if (modelMetadataProvider is ModelMetadataProvider modelMetadataProviderBase)
+                if (mvcOptions.AllowValidatingTopLevelNodes &&
+                    modelMetadataProvider is ModelMetadataProvider modelMetadataProviderBase)
                 {
                     // The default model metadata provider derives from ModelMetadataProvider
                     // and can therefore supply information about attributes applied to parameters.

test/Microsoft.AspNetCore.Mvc.ApiExplorer.Test/DefaultApiDescriptionProviderTest.cs

@@ -326,8 +326,10 @@ namespace Microsoft.AspNetCore.Mvc.Description
         {
             // Arrange
             var action = CreateActionDescriptor();
-            action.AttributeRouteInfo = new AttributeRouteInfo();
+            action.AttributeRouteInfo = new AttributeRouteInfo
-            action.AttributeRouteInfo.Template = template;
+            {
+                Template = template
+            };
 
             // Act
             var descriptions = GetApiDescriptions(action);
@@ -342,8 +344,10 @@ namespace Microsoft.AspNetCore.Mvc.Description
         {
             // Arrange
             var action = CreateActionDescriptor();
-            action.AttributeRouteInfo = new AttributeRouteInfo();
+            action.AttributeRouteInfo = new AttributeRouteInfo
-            action.AttributeRouteInfo.Template = "api/Products/{id1}-{id2:int}";
+            {
+                Template = "api/Products/{id1}-{id2:int}"
+            };
 
             // Act
             var descriptions = GetApiDescriptions(action);
@@ -364,8 +368,10 @@ namespace Microsoft.AspNetCore.Mvc.Description
         {
             // Arrange
             var action = CreateActionDescriptor();
-            action.AttributeRouteInfo = new AttributeRouteInfo();
+            action.AttributeRouteInfo = new AttributeRouteInfo
-            action.AttributeRouteInfo.Template = "api/Products/{id1}-{id2}/{id3:int}/{id4:int?}/{*id5:int}";
+            {
+                Template = "api/Products/{id1}-{id2}/{id3:int}/{id4:int?}/{*id5:int}"
+            };
 
             // Act
             var descriptions = GetApiDescriptions(action);
@@ -685,8 +691,10 @@ namespace Microsoft.AspNetCore.Mvc.Description
             // Arrange
             var action = CreateActionDescriptor(methodName);
             var filter = new ProducesResponseTypeAttribute(typeof(void), statusCode: 204);
-            action.FilterDescriptors = new List<FilterDescriptor>();
+            action.FilterDescriptors = new List<FilterDescriptor>
-            action.FilterDescriptors.Add(new FilterDescriptor(filter, FilterScope.Action));
+            {
+                new FilterDescriptor(filter, FilterScope.Action)
+            };
 
             // Act
             var descriptions = GetApiDescriptions(action);
@@ -717,8 +725,10 @@ namespace Microsoft.AspNetCore.Mvc.Description
                 Type = typeof(Order)
             };
 
-            action.FilterDescriptors = new List<FilterDescriptor>();
+            action.FilterDescriptors = new List<FilterDescriptor>
-            action.FilterDescriptors.Add(new FilterDescriptor(filter, FilterScope.Action));
+            {
+                new FilterDescriptor(filter, FilterScope.Action)
+            };
 
             // Act
             var descriptions = GetApiDescriptions(action);
@@ -758,8 +768,10 @@ namespace Microsoft.AspNetCore.Mvc.Description
             // Arrange
             var action = CreateActionDescriptor(nameof(ReturnsProduct));
             var expectedMediaTypes = new[] { "text/json", "text/xml" };
-            action.FilterDescriptors = new List<FilterDescriptor>();
+            action.FilterDescriptors = new List<FilterDescriptor>
-            action.FilterDescriptors.Add(new FilterDescriptor(new ContentTypeAttribute("text/*"), FilterScope.Action));
+            {
+                new FilterDescriptor(new ContentTypeAttribute("text/*"), FilterScope.Action)
+            };
 
             // Act
             var descriptions = GetApiDescriptions(action);
@@ -780,8 +792,10 @@ namespace Microsoft.AspNetCore.Mvc.Description
                 Type = typeof(Order)
             };
 
-            action.FilterDescriptors = new List<FilterDescriptor>();
+            action.FilterDescriptors = new List<FilterDescriptor>
-            action.FilterDescriptors.Add(new FilterDescriptor(filter, FilterScope.Action));
+            {
+                new FilterDescriptor(filter, FilterScope.Action)
+            };
 
             var formatters = CreateOutputFormatters();
 
@@ -843,8 +857,10 @@ namespace Microsoft.AspNetCore.Mvc.Description
             // Arrange
             var action = CreateActionDescriptor(nameof(AcceptsProduct_Body));
 
-            action.FilterDescriptors = new List<FilterDescriptor>();
+            action.FilterDescriptors = new List<FilterDescriptor>
-            action.FilterDescriptors.Add(new FilterDescriptor(new ContentTypeAttribute("text/*"), FilterScope.Action));
+            {
+                new FilterDescriptor(new ContentTypeAttribute("text/*"), FilterScope.Action)
+            };
 
             // Act
             var descriptions = GetApiDescriptions(action);
@@ -863,8 +879,10 @@ namespace Microsoft.AspNetCore.Mvc.Description
             // Arrange
             var action = CreateActionDescriptor(nameof(AcceptsProduct_Body));
 
-            action.FilterDescriptors = new List<FilterDescriptor>();
+            action.FilterDescriptors = new List<FilterDescriptor>
-            action.FilterDescriptors.Add(new FilterDescriptor(new ContentTypeAttribute("text/*"), FilterScope.Action));
+            {
+                new FilterDescriptor(new ContentTypeAttribute("text/*"), FilterScope.Action)
+            };
 
             var formatters = CreateInputFormatters();
 
@@ -914,7 +932,7 @@ namespace Microsoft.AspNetCore.Mvc.Description
         }
 
         [Fact]
-        public void GetApiDescription_ParameterDescription_IsRequired()
+        public void GetApiDescription_ParameterDescription_IsRequiredSet()
         {
             // Arrange
             var action = CreateActionDescriptor(nameof(RequiredParameter));
@@ -932,6 +950,25 @@ namespace Microsoft.AspNetCore.Mvc.Description
             Assert.True(parameter.ModelMetadata.IsBindingRequired);
         }
 
+        [Fact]
+        public void GetApiDescription_ParameterDescription_IsRequiredNotSet_IfNotValiatingTopLevelNodes()
+        {
+            // Arrange
+            var action = CreateActionDescriptor(nameof(RequiredParameter));
+
+            // Act
+            var descriptions = GetApiDescriptions(action, allowValidatingTopLevelNodes: false);
+
+            // Assert
+            var description = Assert.Single(descriptions);
+            var parameter = Assert.Single(description.ParameterDescriptions);
+            Assert.Equal("name", parameter.Name);
+            Assert.Same(BindingSource.ModelBinding, parameter.Source);
+            Assert.Equal(typeof(string), parameter.Type);
+            Assert.False(parameter.ModelMetadata.IsRequired);
+            Assert.False(parameter.ModelMetadata.IsBindingRequired);
+        }
+
         [Fact]
         public void GetApiDescription_ParameterDescription_SourceFromRouteData()
         {
@@ -1382,11 +1419,15 @@ namespace Microsoft.AspNetCore.Mvc.Description
         private IReadOnlyList<ApiDescription> GetApiDescriptions(
             ActionDescriptor action,
             List<MockInputFormatter> inputFormatters = null,
-            List<MockOutputFormatter> outputFormatters = null)
+            List<MockOutputFormatter> outputFormatters = null,
+            bool allowValidatingTopLevelNodes = true)
         {
             var context = new ApiDescriptionProviderContext(new ActionDescriptor[] { action });
 
-            var options = new MvcOptions();
+            var options = new MvcOptions
+            {
+                AllowValidatingTopLevelNodes = allowValidatingTopLevelNodes,
+            };
             foreach (var formatter in inputFormatters ?? CreateInputFormatters())
             {
                 options.InputFormatters.Add(formatter);
@@ -1397,9 +1438,7 @@ namespace Microsoft.AspNetCore.Mvc.Description
                 options.OutputFormatters.Add(formatter);
             }
 
-            var optionsAccessor = new Mock<IOptions<MvcOptions>>();
+            var optionsAccessor = Options.Create(options);
-            optionsAccessor.SetupGet(o => o.Value)
-                .Returns(options);
 
             var constraintResolver = new Mock<IInlineConstraintResolver>();
             constraintResolver.Setup(c => c.ResolveConstraint("int"))
@@ -1408,7 +1447,7 @@ namespace Microsoft.AspNetCore.Mvc.Description
             var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
 
             var provider = new DefaultApiDescriptionProvider(
-                optionsAccessor.Object,
+                optionsAccessor,
                 constraintResolver.Object,
                 modelMetadataProvider);
 

test/Microsoft.AspNetCore.Mvc.Core.Test/Internal/ApiBehaviorApplicationModelProviderTest.cs

@@ -501,11 +501,12 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             {
                 InvalidModelStateResponseFactory = _ => null,
             };
-            var optionsProvider = Options.Create(options);
+            var optionsAccessor = Options.Create(options);
+
             modelMetadataProvider = modelMetadataProvider ?? new TestModelMetadataProvider();
             var loggerFactory = NullLoggerFactory.Instance;
 
-            return new ApiBehaviorApplicationModelProvider(optionsProvider, modelMetadataProvider, loggerFactory);
+            return new ApiBehaviorApplicationModelProvider(optionsAccessor, modelMetadataProvider, loggerFactory);
         }
 
         private static ApplicationModelProviderContext GetContext(Type type)

test/Microsoft.AspNetCore.Mvc.Core.Test/Internal/ControllerActionInvokerCacheTest.cs

@@ -13,6 +13,7 @@ using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.Testing.xunit;
 using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
 using Moq;
 using Xunit;
 
@@ -103,6 +104,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new[] { controllerContext.ActionDescriptor });
             var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
             var modelBinderFactory = TestModelBinderFactory.CreateDefault();
+            var mvcOptions = Options.Create(new MvcOptions
+            {
+                AllowValidatingTopLevelNodes = true,
+            });
 
             return new ControllerActionInvokerCache(
                 descriptorProvider,
@@ -110,11 +115,13 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     modelMetadataProvider,
                     modelBinderFactory,
                     Mock.Of<IObjectModelValidator>(),
+                    mvcOptions,
                     NullLoggerFactory.Instance),
                 modelBinderFactory,
                 modelMetadataProvider,
                 filterProviders,
-                Mock.Of<IControllerFactoryProvider>());
+                Mock.Of<IControllerFactoryProvider>(),
+                mvcOptions);
         }
 
         private static ControllerContext CreateControllerContext(FilterDescriptor[] filterDescriptors)

test/Microsoft.AspNetCore.Mvc.Core.Test/Internal/ControllerBinderDelegateProviderTest.cs

@@ -20,6 +20,7 @@ using Microsoft.AspNetCore.Routing;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
 using Moq;
 using Xunit;
 
@@ -27,8 +28,14 @@ namespace Microsoft.AspNetCore.Mvc.Internal
 {
     public class ControllerBinderDelegateProviderTest
     {
+        private static readonly MvcOptions _options = new MvcOptions
+        {
+            AllowValidatingTopLevelNodes = true,
+        };
+        private static readonly IOptions<MvcOptions> _optionsAccessor = Options.Create(_options);
+
         [Fact]
-        public async Task BindActionArgumentsAsync_DoesNotAddActionArgumentsOrCallBinderOrValidator_IfBindingIsNotAllowed_OnParameter()
+        public async Task CreateBinderDelegate_Delegate_DoesNotAddActionArgumentsOrCallBinderOrValidator_IfBindingIsNotAllowed_OnParameter()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -61,6 +68,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new[] { GetModelValidatorProvider(mockValidator.Object) }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -68,7 +76,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 TestModelMetadataProvider.CreateDefaultProvider(),
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -85,7 +94,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_DoesNotAddActionArgumentsOrCallBinderOrValidator_IfBindingIsNotAllowed_OnProperty()
+        public async Task CreateBinderDelegate_Delegate_DoesNotAddActionArgumentsOrCallBinderOrValidator_IfBindingIsNotAllowed_OnProperty()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -109,12 +118,14 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             var factory = GetModelBinderFactory(binder.Object);
             var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
             var controller = new TestController();
+
             var parameterBinder = new ParameterBinder(
                 modelMetadataProvider,
                 factory,
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new[] { GetModelValidatorProvider(mockValidator.Object) }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -122,7 +133,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 TestModelMetadataProvider.CreateDefaultProvider(),
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -139,7 +151,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_DoesNotAddActionArguments_IfBinderReturnsNull()
+        public async Task CreateBinderDelegate_Delegate_DoesNotAddActionArguments_IfBinderReturnsNull()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -155,6 +167,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             binder
                 .Setup(b => b.BindModelAsync(It.IsAny<DefaultModelBindingContext>()))
                 .Returns(Task.CompletedTask);
+
             var factory = GetModelBinderFactory(binder.Object);
             var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
             var parameterBinder = new ParameterBinder(
@@ -163,6 +176,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             var controllerContext = GetControllerContext(actionDescriptor);
@@ -174,7 +188,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -183,7 +198,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_DoesNotAddActionArguments_IfBinderDoesNotSetModel()
+        public async Task CreateBinderDelegate_Delegate_DoesNotAddActionArguments_IfBinderDoesNotSetModel()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -199,6 +214,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             binder
                 .Setup(b => b.BindModelAsync(It.IsAny<DefaultModelBindingContext>()))
                 .Returns(Task.CompletedTask);
+
             var factory = GetModelBinderFactory(binder.Object);
             var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
             var parameterBinder = new ParameterBinder(
@@ -207,6 +223,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             var controllerContext = GetControllerContext(actionDescriptor);
@@ -218,7 +235,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -227,7 +245,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_AddsActionArguments_IfBinderReturnsNotNull()
+        public async Task CreateBinderDelegate_Delegate_AddsActionArguments_IfBinderReturnsNotNull()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -251,6 +269,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     context.Result = ModelBindingResult.Success(value);
                 })
                 .Returns(Task.CompletedTask);
+
             var factory = GetModelBinderFactory(binder.Object);
             var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
             var parameterBinder = new ParameterBinder(
@@ -259,6 +278,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             var controllerContext = GetControllerContext(actionDescriptor);
@@ -270,7 +290,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -280,7 +301,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_GetsMetadataFromParameter()
+        public async Task CreateBinderDelegate_Delegate_GetsMetadataFromParameter()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -307,12 +328,14 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             mockMetadataProvider
                 .Setup(p => p.GetMetadataForParameter(ParameterInfos.NoAttributesParameterInfo))
                 .Returns(modelMetadata.Object);
+
             var parameterBinder = new ParameterBinder(
                 mockMetadataProvider.Object,
                 factory,
                 new DefaultObjectValidator(
                     mockMetadataProvider.Object,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -320,7 +343,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 mockMetadataProvider.Object,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -332,7 +356,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_GetsMetadataFromType_IsMetadataProviderIsNotDefaultMetadataProvider()
+        public async Task CreateBinderDelegate_Delegate_GetsMetadataFromType_IsMetadataProviderIsNotDefaultMetadataProvider()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -357,12 +381,14 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             mockMetadataProvider
                 .Setup(p => p.GetMetadataForType(typeof(Person)))
                 .Returns(modelMetadata.Object);
+
             var parameterBinder = new ParameterBinder(
                 mockMetadataProvider.Object,
                 factory,
                 new DefaultObjectValidator(
                     mockMetadataProvider.Object,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -370,7 +396,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 mockMetadataProvider.Object,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -382,7 +409,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_CallsValidator_IfModelBinderSucceeds()
+        public async Task CreateBinderDelegate_Delegate_CallsValidator_IfModelBinderSucceeds()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -410,6 +437,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new[] { GetModelValidatorProvider(mockValidator.Object) }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
             var controller = new TestController();
             var arguments = new Dictionary<string, object>(StringComparer.Ordinal);
@@ -419,15 +447,13 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
             // Assert
-            mockValidator
+            mockValidator.Verify(o => o.Validate(It.IsAny<ModelValidationContext>()), Times.Once());
-                .Verify(o => o.Validate(
-                    It.IsAny<ModelValidationContext>()),
-            Times.Once());
 
             Assert.False(controllerContext.ModelState.IsValid);
             Assert.Equal(
@@ -436,7 +462,58 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_DoesNotCallValidator_IfModelBinderFails()
+        public async Task CreateBinderDelegate_Delegate_DoesNotCallValidator_IfNotValidatingTopLevelNodes()
+        {
+            // Arrange
+            var actionDescriptor = GetActionDescriptor();
+            actionDescriptor.Parameters.Add(
+                new ControllerParameterDescriptor
+                {
+                    Name = "foo",
+                    ParameterType = typeof(object),
+                    ParameterInfo = ParameterInfos.CustomValidationParameterInfo
+                });
+
+            var controllerContext = GetControllerContext(actionDescriptor);
+            var factory = GetModelBinderFactory("Hello");
+
+            var mockValidator = new Mock<IModelValidator>();
+            mockValidator
+                .Setup(o => o.Validate(It.IsAny<ModelValidationContext>()))
+                .Returns(new[] { new ModelValidationResult("memberName", "some message") });
+
+            // Do not set AllowValidatingTopLevelNodes.
+            var mvcOptions = new MvcOptions();
+
+            var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
+            var parameterBinder = new ParameterBinder(
+                modelMetadataProvider,
+                factory,
+                new DefaultObjectValidator(
+                    modelMetadataProvider,
+                    new[] { GetModelValidatorProvider(mockValidator.Object) }),
+                Options.Create(mvcOptions),
+                NullLoggerFactory.Instance);
+            var controller = new TestController();
+            var arguments = new Dictionary<string, object>(StringComparer.Ordinal);
+
+            // Act
+            var binderDelegate = ControllerBinderDelegateProvider.CreateBinderDelegate(
+                parameterBinder,
+                factory,
+                modelMetadataProvider,
+                actionDescriptor,
+                mvcOptions);
+
+            await binderDelegate(controllerContext, controller, arguments);
+
+            // Assert
+            Assert.True(controllerContext.ModelState.IsValid);
+            mockValidator.Verify(o => o.Validate(It.IsAny<ModelValidationContext>()), Times.Never());
+        }
+
+        [Fact]
+        public async Task CreateBinderDelegate_Delegate_DoesNotCallValidator_IfModelBinderFails()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -467,6 +544,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -474,7 +552,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -486,7 +565,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_CallsValidator_ForControllerProperties_IfModelBinderSucceeds()
+        public async Task CreateBinderDelegate_Delegate_CallsValidator_ForControllerProperties_IfModelBinderSucceeds()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -508,13 +587,13 @@ namespace Microsoft.AspNetCore.Mvc.Internal
 
             var factory = GetModelBinderFactory("Hello");
             var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
-
             var parameterBinder = new ParameterBinder(
                 modelMetadataProvider,
                 factory,
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new[] { GetModelValidatorProvider(mockValidator.Object) }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -522,15 +601,13 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
             // Assert
-            mockValidator
+            mockValidator.Verify(o => o.Validate(It.IsAny<ModelValidationContext>()), Times.Once());
-                .Verify(o => o.Validate(
-                    It.IsAny<ModelValidationContext>()),
-                Times.Once());
             Assert.False(controllerContext.ModelState.IsValid);
             Assert.Equal(
                 "some message",
@@ -567,6 +644,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 modelMetadataProvider,
                 factory,
                 mockValidator.Object,
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -574,7 +652,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -583,7 +662,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_DoesNotCallValidator_ForControllerProperties_IfModelBinderFails()
+        public async Task CreateBinderDelegate_Delegate_DoesNotCallValidator_ForControllerProperties_IfModelBinderFails()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -613,6 +692,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new[] { GetModelValidatorProvider(mockValidator.Object) }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -620,7 +700,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -632,7 +713,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_SetsControllerProperties_ForReferenceTypes()
+        public async Task CreateBinderDelegate_Delegate_SetsControllerProperties_ForReferenceTypes()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -656,6 +737,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -663,7 +745,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -674,7 +757,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_AddsToCollectionControllerProperties()
+        public async Task CreateBinderDelegate_Delegate_AddsToCollectionControllerProperties()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -699,6 +782,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -706,7 +790,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -717,7 +802,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_DoesNotSetNullValues_ForNonNullableProperties()
+        public async Task CreateBinderDelegate_Delegate_DoesNotSetNullValues_ForNonNullableProperties()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -742,6 +827,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Some non default value.
@@ -752,7 +838,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -761,7 +848,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_SetsNullValues_ForNullableProperties()
+        public async Task CreateBinderDelegate_Delegate_SetsNullValues_ForNullableProperties()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -786,6 +873,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Some non default value.
@@ -796,7 +884,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -805,7 +894,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_SupportsRequestPredicate_ForPropertiesAndParameters_NotBound()
+        public async Task CreateBinderDelegate_Delegate_SupportsRequestPredicate_ForPropertiesAndParameters_NotBound()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -851,6 +940,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Some non default value.
@@ -861,7 +951,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -871,7 +962,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_SupportsRequestPredicate_ForPropertiesAndParameters_Bound()
+        public async Task CreateBinderDelegate_Delegate_SupportsRequestPredicate_ForPropertiesAndParameters_Bound()
         {
             // Arrange
             var actionDescriptor = GetActionDescriptor();
@@ -917,6 +1008,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Some non default value.
@@ -927,7 +1019,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -978,7 +1071,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
 
         [Theory]
         [MemberData(nameof(SkippedPropertyData))]
-        public async Task BindActionArgumentsAsync_SkipsReadOnlyControllerProperties(
+        public async Task CreateBinderDelegate_Delegate_SkipsReadOnlyControllerProperties(
             string propertyName,
             Type propertyType,
             Func<object, object> propertyAccessor,
@@ -1007,6 +1100,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -1014,7 +1108,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -1025,7 +1120,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         }
 
         [Fact]
-        public async Task BindActionArgumentsAsync_SetsMultipleControllerProperties()
+        public async Task CreateBinderDelegate_Delegate_SetsMultipleControllerProperties()
         {
             // Arrange
             var boundPropertyTypes = new Dictionary<string, Type>
@@ -1085,6 +1180,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new IModelValidatorProvider[] { }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -1092,7 +1188,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder,
                 factory,
                 modelMetadataProvider,
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, controller, arguments);
 
@@ -1182,6 +1279,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 new EmptyModelMetadataProvider(),
                 factory,
                 new DefaultObjectValidator(modelMetadataProvider, new[] { modelValidatorProvider }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
             parameterBinder.Setup(p => p.BindModelAsync(
                 It.IsAny<ActionContext>(),
@@ -1223,7 +1321,8 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 parameterBinder.Object,
                 factory,
                 TestModelMetadataProvider.CreateDefaultProvider(),
-                actionDescriptor);
+                actionDescriptor,
+                _options);
 
             await binderDelegate(controllerContext, new TestController(), arguments);
 
@@ -1340,10 +1439,12 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             var objectModelValidator = new DefaultObjectValidator(
                 metadataProvider,
                 new[] { modelValidatorProvider });
+
             return new ParameterBinder(
                 metadataProvider,
                 factory,
                 objectModelValidator,
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
         }
 

test/Microsoft.AspNetCore.Mvc.Core.Test/Internal/MiddlewareFilterTest.cs

@@ -35,7 +35,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         public async Task MiddlewareFilter_SetsMiddlewareFilterFeature_OnExecution()
         {
             // Arrange
-            RequestDelegate requestDelegate = (context) => Task.FromResult(true);
+            Task requestDelegate(HttpContext context) => Task.FromResult(true);
             var middlwareFilter = new MiddlewareFilter(requestDelegate);
             var httpContext = new DefaultHttpContext();
             var resourceExecutingContext = GetResourceExecutingContext(httpContext);
@@ -315,8 +315,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         {
             var services = CreateServices();
 
-            var httpContext = new DefaultHttpContext();
+            var httpContext = new DefaultHttpContext
-            httpContext.RequestServices = services.BuildServiceProvider();
+            {
+                RequestServices = services.BuildServiceProvider()
+            };
 
             return httpContext;
         }
@@ -326,8 +328,11 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             var applicationServices = new ServiceCollection();
             var applicationBuilder = new ApplicationBuilder(applicationServices.BuildServiceProvider());
             var middlewareFilterBuilderService = new MiddlewareFilterBuilder(
-                new MiddlewareFilterConfigurationProvider());
+                new MiddlewareFilterConfigurationProvider())
-            middlewareFilterBuilderService.ApplicationBuilder = applicationBuilder;
+            {
+                ApplicationBuilder = applicationBuilder
+            };
+
             return middlewareFilterBuilderService.GetPipeline(middlewarePipelineProviderType);
         }
 
@@ -444,11 +449,16 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         private class TestParameterBinder : ParameterBinder
         {
             private readonly IDictionary<string, object> _actionParameters;
+
             public TestParameterBinder(IDictionary<string, object> actionParameters)
                 : base(
                     new EmptyModelMetadataProvider(),
                     TestModelBinderFactory.CreateDefault(),
                     Mock.Of<IObjectModelValidator>(),
+                    Options.Create(new MvcOptions
+                    {
+                        AllowValidatingTopLevelNodes = true,
+                    }),
                     NullLoggerFactory.Instance)
             {
                 _actionParameters = actionParameters;

test/Microsoft.AspNetCore.Mvc.Core.Test/ModelBinding/ParameterBinderTest.cs

@@ -15,6 +15,7 @@ using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
 using Moq;
 using Xunit;
 
@@ -22,6 +23,11 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
 {
     public class ParameterBinderTest
     {
+        private static readonly IOptions<MvcOptions> _optionsAccessor = Options.Create(new MvcOptions
+        {
+            AllowValidatingTopLevelNodes = true,
+        });
+
         public static TheoryData BindModelAsyncData
         {
             get
@@ -98,7 +104,8 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             var parameterBinder = new ParameterBinder(
                 metadataProvider,
                 factory.Object,
-                Mock.Of< IObjectModelValidator>(),
+                Mock.Of<IObjectModelValidator>(),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             var controllerContext = GetControllerContext();
@@ -150,6 +157,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 metadataProvider,
                 factory.Object,
                 Mock.Of<IObjectModelValidator>(),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             var valueProvider = new SimpleValueProvider
@@ -175,7 +183,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             mockModelMetadata.Setup(o => o.IsBindingRequired).Returns(true);
             mockModelMetadata.Setup(o => o.DisplayName).Returns("Ignored Display Name"); // Bind attribute errors are phrased in terms of the model name, not display name
 
-            var parameterBinder = CreateParameterBinder(mockModelMetadata.Object, validator: null);
+            var parameterBinder = CreateParameterBinder(mockModelMetadata.Object);
             var modelBindingResult = ModelBindingResult.Failed();
 
             // Act
@@ -195,6 +203,37 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 actionContext.ModelState.Single().Value.Errors.Single().ErrorMessage);
         }
 
+        [Fact]
+        public async Task BindModelAsync_DoesNotEnforceTopLevelBindRequired_IfNotValidatingTopLevelNodes()
+        {
+            // Arrange
+            var actionContext = GetControllerContext();
+
+            var mockModelMetadata = CreateMockModelMetadata();
+            mockModelMetadata.Setup(o => o.IsBindingRequired).Returns(true);
+
+            // Bind attribute errors are phrased in terms of the model name, not display name
+            mockModelMetadata.Setup(o => o.DisplayName).Returns("Ignored Display Name");
+
+            // Do not set AllowValidatingTopLevelNodes.
+            var optionsAccessor = Options.Create(new MvcOptions());
+            var parameterBinder = CreateParameterBinder(mockModelMetadata.Object, optionsAccessor: optionsAccessor);
+            var modelBindingResult = ModelBindingResult.Failed();
+
+            // Act
+            var result = await parameterBinder.BindModelAsync(
+                actionContext,
+                CreateMockModelBinder(modelBindingResult),
+                CreateMockValueProvider(),
+                new ParameterDescriptor { Name = "myParam", ParameterType = typeof(Person) },
+                mockModelMetadata.Object,
+                "ignoredvalue");
+
+            // Assert
+            Assert.True(actionContext.ModelState.IsValid);
+            Assert.Empty(actionContext.ModelState);
+        }
+
         [Fact]
         public async Task BindModelAsync_EnforcesTopLevelRequired()
         {
@@ -213,9 +252,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 new RequiredAttribute(),
                 stringLocalizer: null);
 
-            var parameterBinder = CreateParameterBinder(
+            var parameterBinder = CreateParameterBinder(mockModelMetadata.Object, validator);
-                mockModelMetadata.Object,
-                validator);
             var modelBindingResult = ModelBindingResult.Success(null);
 
             // Act
@@ -235,6 +272,43 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 actionContext.ModelState.Single().Value.Errors.Single().ErrorMessage);
         }
 
+        [Fact]
+        public async Task BindModelAsync_DoesNotEnforceTopLevelRequired_IfNotValidatingTopLevelNodes()
+        {
+            // Arrange
+            var actionContext = GetControllerContext();
+            var mockModelMetadata = CreateMockModelMetadata();
+            mockModelMetadata.Setup(o => o.IsRequired).Returns(true);
+            mockModelMetadata.Setup(o => o.DisplayName).Returns("My Display Name");
+            mockModelMetadata.Setup(o => o.ValidatorMetadata).Returns(new[]
+            {
+                new RequiredAttribute()
+            });
+
+            var validator = new DataAnnotationsModelValidator(
+                new ValidationAttributeAdapterProvider(),
+                new RequiredAttribute(),
+                stringLocalizer: null);
+
+            // Do not set AllowValidatingTopLevelNodes.
+            var optionsAccessor = Options.Create(new MvcOptions());
+            var parameterBinder = CreateParameterBinder(mockModelMetadata.Object, validator, optionsAccessor);
+            var modelBindingResult = ModelBindingResult.Success(null);
+
+            // Act
+            var result = await parameterBinder.BindModelAsync(
+                actionContext,
+                CreateMockModelBinder(modelBindingResult),
+                CreateMockValueProvider(),
+                new ParameterDescriptor { Name = "myParam", ParameterType = typeof(Person) },
+                mockModelMetadata.Object,
+                "ignoredvalue");
+
+            // Assert
+            Assert.True(actionContext.ModelState.IsValid);
+            Assert.Empty(actionContext.ModelState);
+        }
+
         [Fact]
         public async Task BindModelAsync_EnforcesTopLevelDataAnnotationsAttribute()
         {
@@ -252,9 +326,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 validationAttribute,
                 stringLocalizer: null);
 
-            var parameterBinder = CreateParameterBinder(
+            var parameterBinder = CreateParameterBinder(mockModelMetadata.Object, validator);
-                mockModelMetadata.Object,
-                validator);
             var modelBindingResult = ModelBindingResult.Success(123);
 
             // Act
@@ -353,7 +425,8 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
 
         private static ParameterBinder CreateParameterBinder(
             ModelMetadata modelMetadata,
-            IModelValidator validator)
+            IModelValidator validator = null,
+            IOptions<MvcOptions> optionsAccessor = null)
         {
             var mockModelMetadataProvider = new Mock<IModelMetadataProvider>(MockBehavior.Strict);
             mockModelMetadataProvider
@@ -361,12 +434,14 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 .Returns(modelMetadata);
 
             var mockModelBinderFactory = new Mock<IModelBinderFactory>(MockBehavior.Strict);
+            optionsAccessor = optionsAccessor ?? _optionsAccessor;
             return new ParameterBinder(
                 mockModelMetadataProvider.Object,
                 mockModelBinderFactory.Object,
                 new DefaultObjectValidator(
                     mockModelMetadataProvider.Object,
                     new[] { GetModelValidatorProvider(validator) }),
+                optionsAccessor,
                 NullLoggerFactory.Instance);
         }
 

test/Microsoft.AspNetCore.Mvc.FunctionalTests/CombineAuthorizeTests.cs

@@ -1,43 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-using System;
-using System.Linq;
-using System.Net;
-using System.Net.Http;
-using System.Threading.Tasks;
-using SecurityWebSite;
-using Xunit;
-
-namespace Microsoft.AspNetCore.Mvc.FunctionalTests
-{
-    public class CombineAuthorizeTests : IClassFixture<MvcTestFixture<StartupWithGlobalAuthorizeAndAllowCombiningAuthorizeFilters>>
-    {
-        public CombineAuthorizeTests(MvcTestFixture<StartupWithGlobalAuthorizeAndAllowCombiningAuthorizeFilters> fixture)
-        {
-            Client = fixture.CreateDefaultClient();
-        }
-
-        public HttpClient Client { get; }
-
-        [Fact]
-        public async Task CanAuthorizeWithOnlyCookie2()
-        {
-            // Arrange & Act
-            var response = await Client.PostAsync("http://localhost/Administration/SignInCookie2", null);
-
-            // Assert
-            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
-            Assert.True(response.Headers.Contains("Set-Cookie"));
-
-            var cookie2 = response.Headers.GetValues("Set-Cookie").SingleOrDefault();
-
-            var request = new HttpRequestMessage(HttpMethod.Get, "http://localhost/Administration/EitherCookie");
-            request.Headers.Add("Cookie", cookie2);
-
-            response = await Client.SendAsync(request);
-            var body = await response.Content.ReadAsStringAsync();
-            Assert.Equal("Administration.EitherCookie:AuthorizeCount=1", body);
-         }
-    }
-}

test/Microsoft.AspNetCore.Mvc.FunctionalTests/GlobalAuthorizationFilterTest.cs

@@ -6,7 +6,9 @@ using System.Net;
 using System.Net.Http;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Hosting;
-using Microsoft.AspNetCore.TestHost;
+using Microsoft.AspNetCore.Mvc.Infrastructure;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.Extensions.DependencyInjection;
 using Xunit;
 
 namespace Microsoft.AspNetCore.Mvc.FunctionalTests
@@ -15,8 +17,8 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
     {
         public GlobalAuthorizationFilterTest(MvcTestFixture<SecurityWebSite.StartupWithGlobalDenyAnonymousFilter> fixture)
         {
-            var factory = fixture.Factories.FirstOrDefault() ?? fixture.WithWebHostBuilder(ConfigureWebHostBuilder);
+            Factory = fixture.Factories.FirstOrDefault() ?? fixture.WithWebHostBuilder(ConfigureWebHostBuilder);
-            Client = factory.CreateDefaultClient();
+            Client = Factory.CreateDefaultClient();
         }
 
         private static void ConfigureWebHostBuilder(IWebHostBuilder builder) =>
@@ -24,6 +26,8 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
 
         public HttpClient Client { get; }
 
+        public WebApplicationFactory<SecurityWebSite.StartupWithGlobalDenyAnonymousFilter> Factory { get; }
+
         [Fact]
         public async Task DeniesAnonymousUsers_ByDefault()
         {
@@ -51,10 +55,15 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
         }
 
         [Fact]
-        public async Task AuthorizationPoliciesDoNotCombineByDefault()
+        public async Task AuthorizationPoliciesDoNotCombine_WithV2_0()
         {
             // Arrange & Act
-            var response = await Client.PostAsync("http://localhost/Administration/SignInCookie2", null);
+            var factory = Factory.WithWebHostBuilder(
+                builder => builder.ConfigureServices(
+                    services => services.Configure<MvcCompatibilityOptions>(
+                        options => options.CompatibilityVersion = CompatibilityVersion.Version_2_0)));
+            var client = factory.CreateDefaultClient();
+            var response = await client.PostAsync("http://localhost/Administration/SignInCookie2", null);
 
             // Assert
             Assert.Equal(HttpStatusCode.OK, response.StatusCode);
@@ -65,8 +74,8 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             var request = new HttpRequestMessage(HttpMethod.Get, "http://localhost/Administration/EitherCookie");
             request.Headers.Add("Cookie", cookie2);
 
-            // Will fail because default cookie is not sent so [Authorize] fails
+            // Will fail because default cookie is not sent so [Authorize] fails.
-            response = await Client.SendAsync(request);
+            response = await client.SendAsync(request);
             Assert.Equal(HttpStatusCode.Redirect, response.StatusCode);
             Assert.NotNull(response.Headers.Location);
             Assert.Equal(
@@ -74,5 +83,28 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
                 response.Headers.Location.ToString());
         }
 
-    }
+        [Fact]
+        public async Task AuthorizationPoliciesCombine_WithV2_1()
+        {
+            // Arrange & Act 1
+            var response = await Client.PostAsync("http://localhost/Administration/SignInCookie2", null);
+
+            // Assert 1
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.True(response.Headers.Contains("Set-Cookie"));
+
+            // Arrange 2
+            var cookie2 = response.Headers.GetValues("Set-Cookie").SingleOrDefault();
+            var request = new HttpRequestMessage(HttpMethod.Get, "http://localhost/Administration/EitherCookie");
+            request.Headers.Add("Cookie", cookie2);
+
+            // Act 2: Will succeed because, with AllowCombiningAuthorizeFilters true, [Authorize] allows either cookie.
+            response = await Client.SendAsync(request);
+
+            // Assert 2
+            Assert.Equal(HttpStatusCode.OK, response.StatusCode);
+            Assert.Null(response.Headers.Location);
+        }
+
+   }
 }

test/Microsoft.AspNetCore.Mvc.FunctionalTests/Infrastructure/MvcTestFixture.cs

@@ -1,20 +1,26 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-using System;
 using System.Globalization;
-using System.IO;
 using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.AspNetCore.TestHost;
+using Microsoft.Extensions.DependencyInjection;
 
 namespace Microsoft.AspNetCore.Mvc.FunctionalTests
 {
     public class MvcTestFixture<TStartup> : WebApplicationFactory<TStartup>
         where TStartup : class
     {
-        protected override void ConfigureWebHost(IWebHostBuilder builder) =>
+        protected override void ConfigureWebHost(IWebHostBuilder builder)
-            builder.UseRequestCulture<TStartup>("en-GB", "en-US");
+        {
+            builder
+                .UseRequestCulture<TStartup>("en-GB", "en-US")
+                .ConfigureServices(
+                    services => services.Configure<MvcCompatibilityOptions>(
+                        options => options.CompatibilityVersion = CompatibilityVersion.Version_2_1));
+        }
 
         protected override TestServer CreateServer(IWebHostBuilder builder)
         {

test/Microsoft.AspNetCore.Mvc.FunctionalTests/InputFormatterTests.cs

@@ -109,9 +109,7 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
 
             // Assert
             Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
-
+            Assert.Equal("{\"\":[\"Unexpected end when reading JSON. Path '', line 1, position 1.\"]}", responseBody);
-            // Update me in 3.0 xD
-            Assert.Equal("{\"\":[\"The input was not valid.\"]}", responseBody);
         }
 
         [Theory]

test/Microsoft.AspNetCore.Mvc.IntegrationTests/BodyValidationIntegrationTests.cs

@@ -453,7 +453,18 @@ namespace Microsoft.AspNetCore.Mvc.IntegrationTests
         public async Task FromBodyAndRequiredOnValueTypeProperty_EmptyBody_JsonFormatterAddsModelStateError()
         {
             // Arrange
-            var parameterBinder = ModelBindingTestHelper.GetParameterBinder();
+            var testContext = ModelBindingTestHelper.GetTestContext(
+                request =>
+                {
+                    request.Body = new MemoryStream(Encoding.UTF8.GetBytes(string.Empty));
+                    request.ContentType = "application/json";
+                });
+
+            // Override the AllowInputFormatterExceptionMessages setting ModelBindingTestHelper chooses.
+            var options = testContext.GetService<IOptions<MvcJsonOptions>>().Value;
+            options.AllowInputFormatterExceptionMessages = false;
+
+            var parameterBinder = ModelBindingTestHelper.GetParameterBinder(testContext.HttpContext.RequestServices);
             var parameter = new ParameterDescriptor
             {
                 Name = "Parameter1",
@@ -464,13 +475,6 @@ namespace Microsoft.AspNetCore.Mvc.IntegrationTests
                 ParameterType = typeof(Person4)
             };
 
-            var testContext = ModelBindingTestHelper.GetTestContext(
-                request =>
-                {
-                    request.Body = new MemoryStream(Encoding.UTF8.GetBytes(string.Empty));
-                    request.ContentType = "application/json";
-                });
-
             var modelState = testContext.ModelState;
 
             // Act
@@ -549,7 +553,18 @@ namespace Microsoft.AspNetCore.Mvc.IntegrationTests
         public async Task FromBodyWithInvalidPropertyData_JsonFormatterAddsModelError()
         {
             // Arrange
-            var parameterBinder = ModelBindingTestHelper.GetParameterBinder();
+            var testContext = ModelBindingTestHelper.GetTestContext(
+                request =>
+                {
+                    request.Body = new MemoryStream(Encoding.UTF8.GetBytes("{ \"Number\": \"not a number\" }"));
+                    request.ContentType = "application/json";
+                });
+
+            // Override the AllowInputFormatterExceptionMessages setting ModelBindingTestHelper chooses.
+            var options = testContext.GetService<IOptions<MvcJsonOptions>>().Value;
+            options.AllowInputFormatterExceptionMessages = false;
+
+            var parameterBinder = ModelBindingTestHelper.GetParameterBinder(testContext.HttpContext.RequestServices);
             var parameter = new ParameterDescriptor
             {
                 Name = "Parameter1",
@@ -560,13 +575,6 @@ namespace Microsoft.AspNetCore.Mvc.IntegrationTests
                 ParameterType = typeof(Person5)
             };
 
-            var testContext = ModelBindingTestHelper.GetTestContext(
-                request =>
-                {
-                    request.Body = new MemoryStream(Encoding.UTF8.GetBytes("{ \"Number\": \"not a number\" }"));
-                    request.ContentType = "application/json";
-                });
-
             var modelState = testContext.ModelState;
 
             // Act
@@ -615,10 +623,10 @@ namespace Microsoft.AspNetCore.Mvc.IntegrationTests
                 {
                     request.Body = new MemoryStream(Encoding.UTF8.GetBytes(string.Empty));
                     request.ContentType = "application/json";
-                });
+                },
+                options => options.AllowEmptyInputInBodyModelBinding = allowEmptyInputInBodyModelBindingSetting);
 
             var optionsAccessor = testContext.GetService<IOptions<MvcOptions>>();
-            optionsAccessor.Value.AllowEmptyInputInBodyModelBinding = allowEmptyInputInBodyModelBindingSetting;
             var modelState = testContext.ModelState;
 
             var parameterBinder = ModelBindingTestHelper.GetParameterBinder(optionsAccessor.Value);

test/Microsoft.AspNetCore.Mvc.IntegrationTests/ComplexTypeModelBinderIntegrationTest.cs

@@ -2701,7 +2701,7 @@ namespace Microsoft.AspNetCore.Mvc.IntegrationTests
 
             entry = Assert.Single(modelState, e => e.Key == "Info.Value.GpsCoordinates").Value;
             Assert.Equal("10,20", entry.AttemptedValue);
-            Assert.Equal(new[] { "10", "20" }, entry.RawValue);
+            Assert.Equal("10,20", entry.RawValue);
         }
 
         private static void SetJsonBodyContent(HttpRequest request, string content)

test/Microsoft.AspNetCore.Mvc.IntegrationTests/HeaderModelBinderIntegrationTest.cs

@@ -441,14 +441,6 @@ namespace Microsoft.AspNetCore.Mvc.IntegrationTests
             Action<HttpRequest> updateRequest = null,
             Action<MvcOptions> updateOptions = null)
         {
-            if (updateOptions == null)
-            {
-                updateOptions = o =>
-                {
-                    o.AllowBindingHeaderValuesToNonStringModelTypes = true;
-                };
-            }
-
             return ModelBindingTestHelper.GetTestContext(updateRequest, updateOptions);
         }
 

test/Microsoft.AspNetCore.Mvc.IntegrationTests/ModelBindingTestHelper.cs

@@ -71,6 +71,7 @@ namespace Microsoft.AspNetCore.Mvc.IntegrationTests
                 new DefaultObjectValidator(
                     metadataProvider,
                     new[] { new CompositeModelValidatorProvider(GetModelValidatorProviders(options)) }),
+                options,
                 NullLoggerFactory.Instance);
         }
 
@@ -95,6 +96,7 @@ namespace Microsoft.AspNetCore.Mvc.IntegrationTests
                 new DefaultObjectValidator(
                     metadataProvider,
                     new[] { new CompositeModelValidatorProvider(GetModelValidatorProviders(options)) }),
+                options,
                 NullLoggerFactory.Instance);
         }
 
@@ -151,7 +153,9 @@ namespace Microsoft.AspNetCore.Mvc.IntegrationTests
             var serviceCollection = new ServiceCollection();
             serviceCollection.AddAuthorization();
             serviceCollection.AddSingleton(new ApplicationPartManager());
-            serviceCollection.AddMvc();
+            serviceCollection
+                .AddMvc()
+                .SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
             serviceCollection
                 .AddSingleton<ObjectPoolProvider, DefaultObjectPoolProvider>()
                 .AddTransient<ILoggerFactory, LoggerFactory>()

test/Microsoft.AspNetCore.Mvc.RazorPages.Test/Internal/PageActionInvokerProviderTest.cs

@@ -487,10 +487,16 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
 
             var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
             var modelBinderFactory = TestModelBinderFactory.CreateDefault();
+            var mvcOptions = new MvcOptions
+            {
+                AllowValidatingTopLevelNodes = true,
+            };
+
             var parameterBinder = new ParameterBinder(
                 modelMetadataProvider,
                 TestModelBinderFactory.CreateDefault(),
                 Mock.Of<IObjectModelValidator>(),
+                Options.Create(mvcOptions),
                 NullLoggerFactory.Instance);
 
             return new PageActionInvokerProvider(

test/Microsoft.AspNetCore.Mvc.RazorPages.Test/Internal/PageActionInvokerTest.cs

@@ -26,6 +26,7 @@ using Microsoft.AspNetCore.Testing;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
 using Moq;
 using Xunit;
 
@@ -1240,10 +1241,16 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
             }
 
             var metadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
+            var mvcOptions = new MvcOptions
+            {
+                AllowValidatingTopLevelNodes = true,
+            };
+
             return new ParameterBinder(
                 metadataProvider,
                 factory,
                 new DefaultObjectValidator(metadataProvider, new[] { validator }),
+                Options.Create(mvcOptions),
                 NullLoggerFactory.Instance);
         }
 

test/Microsoft.AspNetCore.Mvc.RazorPages.Test/Internal/PageBinderFactoryTest.cs

@@ -15,6 +15,7 @@ using Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
 using Moq;
 using Xunit;
 
@@ -22,6 +23,12 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
 {
     public class PageBinderFactoryTest
     {
+        private static readonly MvcOptions _options = new MvcOptions
+        {
+            AllowValidatingTopLevelNodes = true,
+        };
+        private static readonly IOptions<MvcOptions> _optionsAccessor = Options.Create(_options);
+
         [Fact]
         public void GetModelBinderFactory_ReturnsNullIfPageHasNoBoundProperties()
         {
@@ -37,6 +44,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
                 modelMetadataProvider,
                 modelBinderFactory,
                 Mock.Of<IObjectModelValidator>(),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -62,6 +70,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
                 modelMetadataProvider,
                 modelBinderFactory,
                 Mock.Of<IObjectModelValidator>(),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -86,6 +95,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
                 modelMetadataProvider,
                 modelBinderFactory,
                 Mock.Of<IObjectModelValidator>(),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -111,6 +121,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
                 modelMetadataProvider,
                 modelBinderFactory,
                 Mock.Of<IObjectModelValidator>(),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -135,6 +146,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
                 modelMetadataProvider,
                 modelBinderFactory,
                 Mock.Of<IObjectModelValidator>(),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -160,6 +172,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
                 modelMetadataProvider,
                 modelBinderFactory,
                 Mock.Of<IObjectModelValidator>(),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             // Act
@@ -285,7 +298,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
 
             // Assert
             // Verify that the page properties were not bound.
-            Assert.Equal(default(int), page.Id);
+            Assert.Equal(default, page.Id);
             Assert.Null(page.RouteDifferentValue);
 
             Assert.Equal(10, model.Id);
@@ -541,6 +554,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new[] { TestModelValidatorProvider.CreateDefaultProvider() }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             var factory = PageBinderFactory.CreatePropertyBinder(binder, modelMetadataProvider, modelBinderFactory, actionDescriptor);
@@ -581,13 +595,13 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
 
             var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
             var modelBinderFactory = TestModelBinderFactory.CreateDefault();
-
             var factory = PageBinderFactory.CreateHandlerBinder(
                 parameterBinder,
                 modelMetadataProvider,
                 modelBinderFactory,
                 actionDescriptor,
-                actionDescriptor.HandlerMethods[0]);
+                actionDescriptor.HandlerMethods[0],
+                _options);
 
             var page = new PageWithProperty
             {
@@ -625,13 +639,13 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
 
             var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
             var modelBinderFactory = TestModelBinderFactory.CreateDefault();
-
             var factory = PageBinderFactory.CreateHandlerBinder(
                 parameterBinder,
                 modelMetadataProvider,
                 modelBinderFactory,
                 actionDescriptor,
-                actionDescriptor.HandlerMethods[0]);
+                actionDescriptor.HandlerMethods[0],
+                _options);
 
             var page = new PageWithProperty
             {
@@ -659,13 +673,13 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
 
             var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
             var modelBinderFactory = TestModelBinderFactory.CreateDefault();
-
             var parameterBinder = new ParameterBinder(
                 modelMetadataProvider,
                 modelBinderFactory,
                 new DefaultObjectValidator(
                     modelMetadataProvider,
                     new[] { TestModelValidatorProvider.CreateDefaultProvider() }),
+                _optionsAccessor,
                 NullLoggerFactory.Instance);
 
             var factory = PageBinderFactory.CreateHandlerBinder(
@@ -673,7 +687,8 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
                 modelMetadataProvider,
                 modelBinderFactory,
                 actionDescriptor,
-                actionDescriptor.HandlerMethods[0]);
+                actionDescriptor.HandlerMethods[0],
+                _options);
 
             var page = new PageWithProperty
             {
@@ -690,13 +705,62 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
             var modelState = page.PageContext.ModelState;
             Assert.False(modelState.IsValid);
             Assert.Collection(
-                page.PageContext.ModelState,
+                modelState,
                 kvp =>
                 {
                     Assert.Equal("name", kvp.Key);
                 });
         }
 
+        [Fact]
+        public async Task CreateHandlerBinder_DoesNotValidateTopLevelParameters_IfDisabled()
+        {
+            // Arrange
+            var type = typeof(PageModelWithExecutors);
+            var actionDescriptor = GetActionDescriptorWithHandlerMethod(
+                type,
+                nameof(PageModelWithExecutors.OnPostWithValidation));
+
+            // Act
+
+            var modelMetadataProvider = TestModelMetadataProvider.CreateDefaultProvider();
+            var modelBinderFactory = TestModelBinderFactory.CreateDefault();
+            var mvcOptions = new MvcOptions();
+
+            var parameterBinder = new ParameterBinder(
+                modelMetadataProvider,
+                modelBinderFactory,
+                new DefaultObjectValidator(
+                    modelMetadataProvider,
+                    new[] { TestModelValidatorProvider.CreateDefaultProvider() }),
+                Options.Create(mvcOptions),
+                NullLoggerFactory.Instance);
+
+            var factory = PageBinderFactory.CreateHandlerBinder(
+                parameterBinder,
+                modelMetadataProvider,
+                modelBinderFactory,
+                actionDescriptor,
+                actionDescriptor.HandlerMethods[0],
+                mvcOptions);
+
+            var page = new PageWithProperty
+            {
+                PageContext = GetPageContext()
+            };
+
+            var model = new PageModelWithExecutors();
+            var arguments = new Dictionary<string, object>();
+
+            // Act
+            await factory(page.PageContext, arguments);
+
+            // Assert
+            var modelState = page.PageContext.ModelState;
+            Assert.True(modelState.IsValid);
+            Assert.Empty(modelState);
+        }
+
         private static CompiledPageActionDescriptor GetActionDescriptorWithHandlerMethod(Type type, string method)
         {
             var handlerMethodInfo = type.GetMethod(method);
@@ -756,6 +820,7 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
                     TestModelMetadataProvider.CreateDefaultProvider(),
                     TestModelBinderFactory.CreateDefault(),
                     Mock.Of<IObjectModelValidator>(),
+                    _optionsAccessor,
                     NullLoggerFactory.Instance)
             {
                 _args = args;
@@ -914,8 +979,6 @@ namespace Microsoft.AspNetCore.Mvc.RazorPages.Internal
             public void OnPostWithValidation([Required] string name)
             {
             }
-
         }
-
     }
 }

test/WebSites/RazorPagesWebSite/Startup.cs

@@ -25,8 +25,7 @@ namespace RazorPagesWebSite
                     options.Conventions.AddPageRoute("/Pages/NotTheRoot", string.Empty);
                     options.Conventions.Add(new CustomModelTypeConvention());
                 })
-                .WithRazorPagesAtContentRoot()
+                .WithRazorPagesAtContentRoot();
-                .SetCompatibilityVersion(Microsoft.AspNetCore.Mvc.CompatibilityVersion.Version_2_1);
         }
 
         public void Configure(IApplicationBuilder app)

test/WebSites/RazorPagesWebSite/StartupWithBasePath.cs

@@ -1,8 +1,8 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Authentication.Cookies;
+using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.DependencyInjection;
 using RazorPagesWebSite.Conventions;
 
@@ -24,8 +24,7 @@ namespace RazorPagesWebSite
                     options.Conventions.AuthorizeAreaFolder("Accounts", "/RequiresAuth");
                     options.Conventions.AllowAnonymousToAreaPage("Accounts", "/RequiresAuth/AllowAnonymous");
                     options.Conventions.Add(new CustomModelTypeConvention());
-                })
+                });
-                .SetCompatibilityVersion(Microsoft.AspNetCore.Mvc.CompatibilityVersion.Version_2_1);
         }
 
         public void Configure(IApplicationBuilder app)

test/WebSites/SecurityWebSite/StartupWithGlobalAuthorizeAndAllowCombiningAuthorizeFilters.cs

@@ -1,47 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-using Microsoft.AspNetCore.Authentication.Cookies;
-using Microsoft.AspNetCore.Authorization.Policy;
-using Microsoft.AspNetCore.Builder;
-using Microsoft.AspNetCore.Mvc.Authorization;
-using Microsoft.Extensions.DependencyInjection;
-
-namespace SecurityWebSite
-{
-    public class StartupWithGlobalAuthorizeAndAllowCombiningAuthorizeFilters
-    {
-        // This method gets called by the runtime. Use this method to add services to the container.
-        public void ConfigureServices(IServiceCollection services)
-        {
-            // Add framework services.
-            services.AddMvc(o =>
-            {
-                o.AllowCombiningAuthorizeFilters = true;
-                o.Filters.Add(new AuthorizeFilter());
-            });
-
-            services.AddAntiforgery();
-            services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme).AddCookie(options => 
-            {
-                options.LoginPath = "/Home/Login";
-                options.LogoutPath = "/Home/Logout";
-            }).AddCookie("Cookie2");
-
-            services.AddScoped<IPolicyEvaluator, CountingPolicyEvaluator>();
-        }
-
-        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
-        public void Configure(IApplicationBuilder app)
-        {
-            app.UseAuthentication();
-
-            app.UseMvc(routes =>
-            {
-                routes.MapRoute(
-                    name: "default",
-                    template: "{controller=Home}/{action=Index}/{id?}");
-            });
-        }
-    }
-}