Support overrides for client-side validation messages

- #2969
- `RemoteAttribute` did not support `IStringLocalizer` overrides
 - use same `MvcDataAnnotationsLocalizationOptions` property as for other `ValidationAttribute`s
- error message `NumericClientModelValidator` added could not be overridden
 - not related to `IStringLocalizer` because users have no way to set the resource lookup key
 - extend `IModelBindingMessageProvider` to add the necessary `Func<,>`
- also correct problem using resources with `RemoteAttribute` and add lots of tests

src/Microsoft.AspNetCore.Mvc.Abstractions/ModelBinding/Metadata/IModelBindingMessageProvider.cs

@@ -51,5 +51,12 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding.Metadata
         /// </summary>
         /// <value>Default <see cref="string"/> is "The value '{0}' is invalid.".</value>
         Func<string, string> ValueIsInvalidAccessor { get; }
+
+        /// <summary>
+        /// Error message HTML and tag helpers add for client-side validation of numeric formats. Visible in the
+        /// browser if the field for a <c>float</c> property (for example) does not have a correctly-formatted value.
+        /// </summary>
+        /// <value>Default <see cref="string"/> is "The field {0} must be a number.".</value>
+        Func<string, string> ValueMustBeANumberAccessor { get; }
     }
 }

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

@@ -34,6 +34,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             messageProvider.AttemptedValueIsInvalidAccessor = Resources.FormatModelState_AttemptedValueIsInvalid;
             messageProvider.UnknownValueIsInvalidAccessor = Resources.FormatModelState_UnknownValueIsInvalid;
             messageProvider.ValueIsInvalidAccessor = Resources.FormatHtmlGeneration_ValueIsInvalid;
+            messageProvider.ValueMustBeANumberAccessor = Resources.FormatHtmlGeneration_ValueMustBeNumber;
 
             // Set up ModelBinding
             options.ModelBinders.Add(new BinderTypeBasedModelBinder());

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

@@ -44,6 +44,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                     AttemptedValueIsInvalidAccessor = Resources.FormatModelState_AttemptedValueIsInvalid,
                     UnknownValueIsInvalidAccessor = Resources.FormatModelState_UnknownValueIsInvalid,
                     ValueIsInvalidAccessor = Resources.FormatHtmlGeneration_ValueIsInvalid,
+                    ValueMustBeANumberAccessor = Resources.FormatHtmlGeneration_ValueMustBeNumber,
                 };
             }
         }

src/Microsoft.AspNetCore.Mvc.Core/ModelBinding/Metadata/ModelBindingMessageProvider.cs

@@ -16,6 +16,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding.Metadata
         private Func<string, string, string> _attemptedValueIsInvalidAccessor;
         private Func<string, string> _unknownValueIsInvalidAccessor;
         private Func<string, string> _valueIsInvalidAccessor;
+        private Func<string, string> _valueMustBeANumberAccessor;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ModelBindingMessageProvider"/> class.
@@ -42,6 +43,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding.Metadata
             AttemptedValueIsInvalidAccessor = originalProvider.AttemptedValueIsInvalidAccessor;
             UnknownValueIsInvalidAccessor = originalProvider.UnknownValueIsInvalidAccessor;
             ValueIsInvalidAccessor = originalProvider.ValueIsInvalidAccessor;
+            ValueMustBeANumberAccessor = originalProvider.ValueMustBeANumberAccessor;
         }
 
         /// <inheritdoc/>
@@ -151,5 +153,23 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding.Metadata
                 _valueIsInvalidAccessor = value;
             }
         }
+
+        /// <inheritdoc/>
+        public Func<string, string> ValueMustBeANumberAccessor
+        {
+            get
+            {
+                return _valueMustBeANumberAccessor;
+            }
+            set
+            {
+                if (value == null)
+                {
+                    throw new ArgumentNullException(nameof(value));
+                }
+
+                _valueMustBeANumberAccessor = value;
+            }
+        }
     }
 }

src/Microsoft.AspNetCore.Mvc.Core/Properties/Resources.Designer.cs

@@ -1002,38 +1002,6 @@ namespace Microsoft.AspNetCore.Mvc.Core
             return GetString("UrlNotLocal");
         }
 
-        /// <summary>
-        /// The stream must support reading.
-        /// </summary>
-        internal static string HttpRequestStreamReader_StreamNotReadable
-        {
-            get { return GetString("HttpRequestStreamReader_StreamNotReadable"); }
-        }
-
-        /// <summary>
-        /// The stream must support reading.
-        /// </summary>
-        internal static string FormatHttpRequestStreamReader_StreamNotReadable()
-        {
-            return GetString("HttpRequestStreamReader_StreamNotReadable");
-        }
-
-        /// <summary>
-        /// The stream must support writing.
-        /// </summary>
-        internal static string HttpResponseStreamWriter_StreamNotWritable
-        {
-            get { return GetString("HttpResponseStreamWriter_StreamNotWritable"); }
-        }
-
-        /// <summary>
-        /// The stream must support writing.
-        /// </summary>
-        internal static string FormatHttpResponseStreamWriter_StreamNotWritable()
-        {
-            return GetString("HttpResponseStreamWriter_StreamNotWritable");
-        }
-
         /// <summary>
         /// The argument '{0}' is invalid. Empty or null formats are not supported.
         /// </summary>
@@ -1114,6 +1082,22 @@ namespace Microsoft.AspNetCore.Mvc.Core
             return string.Format(CultureInfo.CurrentCulture, GetString("HtmlGeneration_ValueIsInvalid"), p0);
         }
 
+        /// <summary>
+        /// The field {0} must be a number.
+        /// </summary>
+        internal static string HtmlGeneration_ValueMustBeNumber
+        {
+            get { return GetString("HtmlGeneration_ValueMustBeNumber"); }
+        }
+
+        /// <summary>
+        /// The field {0} must be a number.
+        /// </summary>
+        internal static string FormatHtmlGeneration_ValueMustBeNumber(object p0)
+        {
+            return string.Format(CultureInfo.CurrentCulture, GetString("HtmlGeneration_ValueMustBeNumber"), p0);
+        }
+
         private static string GetString(string name, params string[] formatterNames)
         {
             var value = _resourceManager.GetString(name);

src/Microsoft.AspNetCore.Mvc.Core/Resources.resx

@@ -328,4 +328,7 @@
   <data name="HtmlGeneration_ValueIsInvalid" xml:space="preserve">
     <value>The value '{0}' is invalid.</value>
   </data>
+  <data name="HtmlGeneration_ValueMustBeNumber" xml:space="preserve">
+    <value>The field {0} must be a number.</value>
+  </data>
 </root>

src/Microsoft.AspNetCore.Mvc.DataAnnotations/Internal/NumericClientModelValidator.cs

@@ -44,7 +44,8 @@ namespace Microsoft.AspNetCore.Mvc.DataAnnotations.Internal
                 throw new ArgumentNullException(nameof(modelMetadata));
             }
 
-            return Resources.FormatNumericClientModelValidator_FieldMustBeNumber(modelMetadata.GetDisplayName());
+            return modelMetadata.ModelBindingMessageProvider.ValueMustBeANumberAccessor(
+                modelMetadata.GetDisplayName());
         }
     }
 }

src/Microsoft.AspNetCore.Mvc.DataAnnotations/Properties/Resources.Designer.cs

@@ -42,22 +42,6 @@ namespace Microsoft.AspNetCore.Mvc.DataAnnotations
             return GetString("ArgumentCannotBeNullOrEmpty");
         }
 
-        /// <summary>
-        /// The field {0} must be a number.
-        /// </summary>
-        internal static string NumericClientModelValidator_FieldMustBeNumber
-        {
-            get { return GetString("NumericClientModelValidator_FieldMustBeNumber"); }
-        }
-
-        /// <summary>
-        /// The field {0} must be a number.
-        /// </summary>
-        internal static string FormatNumericClientModelValidator_FieldMustBeNumber(object p0)
-        {
-            return string.Format(CultureInfo.CurrentCulture, GetString("NumericClientModelValidator_FieldMustBeNumber"), p0);
-        }
-
         /// <summary>
         /// The '{0}' property of '{1}' must not be null.
         /// </summary>

src/Microsoft.AspNetCore.Mvc.DataAnnotations/Resources.resx

@@ -123,9 +123,6 @@
   <data name="ArgumentCannotBeNullOrEmpty" xml:space="preserve">
     <value>Value cannot be null or empty.</value>
   </data>
-  <data name="NumericClientModelValidator_FieldMustBeNumber" xml:space="preserve">
-    <value>The field {0} must be a number.</value>
-  </data>
   <data name="PropertyOfTypeCannotBeNull" xml:space="preserve">
     <value>The '{0}' property of '{1}' must not be null.</value>
   </data>

src/Microsoft.AspNetCore.Mvc.ViewFeatures/RemoteAttribute.cs

@@ -6,12 +6,14 @@ using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 using System.Globalization;
 using System.Linq;
-using Microsoft.AspNetCore.Mvc.ViewFeatures;
+using Microsoft.AspNetCore.Mvc.DataAnnotations;
-using Microsoft.AspNetCore.Mvc.Internal;
 using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
+using Microsoft.AspNetCore.Mvc.Routing;
+using Microsoft.AspNetCore.Mvc.ViewFeatures;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.AspNetCore.Mvc.Routing;
+using Microsoft.Extensions.Localization;
+using Microsoft.Extensions.Options;
 
 namespace Microsoft.AspNetCore.Mvc
 {
@@ -25,6 +27,8 @@ namespace Microsoft.AspNetCore.Mvc
     {
         private string _additionalFields = string.Empty;
         private string[] _additionalFieldsSplit = new string[0];
+        private bool _checkedForLocalizer;
+        private IStringLocalizer _stringLocalizer;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="RemoteAttribute"/> class.
@@ -33,7 +37,7 @@ namespace Microsoft.AspNetCore.Mvc
         /// Intended for subclasses that support URL generation with no route, action, or controller names.
         /// </remarks>
         protected RemoteAttribute()
-            : base(Resources.RemoteAttribute_RemoteValidationFailed)
+            : base(errorMessageAccessor: () => Resources.RemoteAttribute_RemoteValidationFailed)
         {
             RouteData = new RouteValueDictionary();
         }
@@ -241,8 +245,10 @@ namespace Microsoft.AspNetCore.Mvc
 
             MergeAttribute(context.Attributes, "data-val", "true");
 
-            var errorMessage = FormatErrorMessage(context.ModelMetadata.GetDisplayName());
+            CheckForLocalizer(context);
+            var errorMessage = GetErrorMessage(context.ModelMetadata.GetDisplayName());
             MergeAttribute(context.Attributes, "data-val-remote", errorMessage);
+
             MergeAttribute(context.Attributes, "data-val-remote-url", GetUrl(context));
 
             if (!string.IsNullOrEmpty(HttpMethod))
@@ -272,10 +278,45 @@ namespace Microsoft.AspNetCore.Mvc
                 return new string[0];
             }
 
-            var split = original.Split(',')
+            var split = original
-                                .Select(piece => piece.Trim())
+                .Split(',')
-                                .Where(trimmed => !string.IsNullOrEmpty(trimmed));
+                .Select(piece => piece.Trim())
+                .Where(trimmed => !string.IsNullOrEmpty(trimmed));
+
             return split;
         }
+
+        private void CheckForLocalizer(ClientModelValidationContext context)
+        {
+            if (!_checkedForLocalizer)
+            {
+                _checkedForLocalizer = true;
+
+                var services = context.ActionContext.HttpContext.RequestServices;
+                var options = services.GetRequiredService<IOptions<MvcDataAnnotationsLocalizationOptions>>();
+                var factory = services.GetService<IStringLocalizerFactory>();
+
+                var provider = options.Value.DataAnnotationLocalizerProvider;
+                if (factory != null && provider != null)
+                {
+                    _stringLocalizer = provider(
+                        context.ModelMetadata.ContainerType ?? context.ModelMetadata.ModelType,
+                        factory);
+                }
+            }
+        }
+
+        private string GetErrorMessage(string displayName)
+        {
+            if (_stringLocalizer != null &&
+                !string.IsNullOrEmpty(ErrorMessage) &&
+                string.IsNullOrEmpty(ErrorMessageResourceName) &&
+                ErrorMessageResourceType == null)
+            {
+                return _stringLocalizer[ErrorMessage, displayName];
+            }
+
+            return FormatErrorMessage(displayName);
+        }
     }
 }

test/Microsoft.AspNetCore.Mvc.Abstractions.Test/ModelBinding/ModelStateDictionaryTest.cs

@@ -754,6 +754,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                     (value, name) => "Unexpected InvalidValueWithKnownAttemptedValueAccessor use",
                 UnknownValueIsInvalidAccessor = name => $"Hmm, the supplied value is not valid for { name }.",
                 ValueIsInvalidAccessor = value => "Unexpected InvalidValueWithUnknownModelErrorAccessor use",
+                ValueMustBeANumberAccessor = name => "Unexpected ValueMustBeANumberAccessor use",
             };
             var bindingMetadataProvider = new DefaultBindingMetadataProvider(messageProvider);
             var compositeProvider = new DefaultCompositeMetadataDetailsProvider(new[] { bindingMetadataProvider });
@@ -805,6 +806,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                     (value, name) => $"Hmm, the value '{ value }' is not valid for { name }.",
                 UnknownValueIsInvalidAccessor = name => "Unexpected InvalidValueWithUnknownAttemptedValueAccessor use",
                 ValueIsInvalidAccessor = value => "Unexpected InvalidValueWithUnknownModelErrorAccessor use",
+                ValueMustBeANumberAccessor = name => "Unexpected ValueMustBeANumberAccessor use",
             };
             var bindingMetadataProvider = new DefaultBindingMetadataProvider(messageProvider);
             var compositeProvider = new DefaultCompositeMetadataDetailsProvider(new[] { bindingMetadataProvider });

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

@@ -527,6 +527,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 AttemptedValueIsInvalidAccessor = Resources.FormatModelState_AttemptedValueIsInvalid,
                 UnknownValueIsInvalidAccessor = Resources.FormatModelState_UnknownValueIsInvalid,
                 ValueIsInvalidAccessor = Resources.FormatHtmlGeneration_ValueIsInvalid,
+                ValueMustBeANumberAccessor = Resources.FormatHtmlGeneration_ValueMustBeNumber,
             };
         }
 

test/Microsoft.AspNetCore.Mvc.DataAnnotations.Test/Internal/ModelMetadataProviderTest.cs

@@ -1067,6 +1067,7 @@ namespace Microsoft.AspNetCore.Mvc.DataAnnotations.Internal
                         (value, name) => $"The value '{ value }' is not valid for { name }.",
                     UnknownValueIsInvalidAccessor = name => $"The supplied value is invalid for { name }.",
                     ValueIsInvalidAccessor = value => $"The value '{ value }' is invalid.",
+                    ValueMustBeANumberAccessor = name => $"The field { name } must be a number.",
                 };
             }
 

test/Microsoft.AspNetCore.Mvc.DataAnnotations.Test/Internal/NumericClientModelValidatorTest.cs

@@ -37,6 +37,35 @@ namespace Microsoft.AspNetCore.Mvc.DataAnnotations.Internal
                 kvp => { Assert.Equal("data-val-number", kvp.Key); Assert.Equal(expectedMessage, kvp.Value); });
         }
 
+        [Fact]
+        public void AddValidation_CorrectValidationTypeAndOverriddenErrorMessage()
+        {
+            // Arrange
+            var expectedMessage = "Error message about 'DisplayId' from override.";
+            var provider = new TestModelMetadataProvider();
+            provider
+                .ForProperty(typeof(TypeWithNumericProperty), nameof(TypeWithNumericProperty.Id))
+                .BindingDetails(d => d.ModelBindingMessageProvider.ValueMustBeANumberAccessor =
+                    name => $"Error message about '{ name }' from override.");
+            var metadata = provider.GetMetadataForProperty(
+                typeof(TypeWithNumericProperty),
+                nameof(TypeWithNumericProperty.Id));
+
+            var adapter = new NumericClientModelValidator();
+
+            var actionContext = new ActionContext();
+            var context = new ClientModelValidationContext(actionContext, metadata, provider, new AttributeDictionary());
+
+            // Act
+            adapter.AddValidation(context);
+
+            // Assert
+            Assert.Collection(
+                context.Attributes,
+                kvp => { Assert.Equal("data-val", kvp.Key); Assert.Equal("true", kvp.Value); },
+                kvp => { Assert.Equal("data-val-number", kvp.Key); Assert.Equal(expectedMessage, kvp.Value); });
+        }
+
         [Fact]
         [ReplaceCulture]
         public void AddValidation_DoesNotTrounceExistingAttributes()

test/Microsoft.AspNetCore.Mvc.TestCommon/TestModelMetadataProvider.cs

@@ -116,6 +116,7 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
                 AttemptedValueIsInvalidAccessor = (value, name) => $"The value '{ value }' is not valid for { name }.",
                 UnknownValueIsInvalidAccessor = name => $"The supplied value is invalid for { name }.",
                 ValueIsInvalidAccessor = value => $"The value '{ value }' is invalid.",
+                ValueMustBeANumberAccessor = name => $"The field { name } must be a number.",
             };
         }
 

test/Microsoft.AspNetCore.Mvc.ViewFeatures.Test/Properties/Resources.Designer.cs

@@ -58,6 +58,22 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Test
             return GetString("DisplayAttribute_Name");
         }
 
+        /// <summary>
+        /// Error about '{0}' from resources.
+        /// </summary>
+        internal static string RemoteAttribute_Error
+        {
+            get { return GetString("RemoteAttribute_Error"); }
+        }
+
+        /// <summary>
+        /// Error about '{0}' from resources.
+        /// </summary>
+        internal static string FormatRemoteAttribute_Error(object p0)
+        {
+            return string.Format(CultureInfo.CurrentCulture, GetString("RemoteAttribute_Error"), p0);
+        }
+
         private static string GetString(string name, params string[] formatterNames)
         {
             var value = _resourceManager.GetString(name);

test/Microsoft.AspNetCore.Mvc.ViewFeatures.Test/RemoteAttributeTest.cs

@@ -6,18 +6,22 @@ using System.Text.Encodings.Web;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Http.Internal;
 using Microsoft.AspNetCore.Mvc.Abstractions;
+using Microsoft.AspNetCore.Mvc.DataAnnotations;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
 using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;
 using Microsoft.AspNetCore.Mvc.Routing;
 using Microsoft.AspNetCore.Mvc.ViewFeatures;
 using Microsoft.AspNetCore.Routing;
+using Microsoft.AspNetCore.Testing;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Localization;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Testing;
 using Microsoft.Extensions.Options;
 using Microsoft.Extensions.WebEncoders.Testing;
 using Moq;
 using Xunit;
+using Resources = Microsoft.AspNetCore.Mvc.ViewFeatures.Test.Resources;
 
 namespace Microsoft.AspNetCore.Mvc
 {
@@ -26,7 +30,7 @@ namespace Microsoft.AspNetCore.Mvc
         private static readonly IModelMetadataProvider _metadataProvider = new EmptyModelMetadataProvider();
         private static readonly ModelMetadata _metadata = _metadataProvider.GetMetadataForProperty(
             typeof(string),
-            "Length");
+            nameof(string.Length));
 
         public static TheoryData<string> SomeNames
         {
@@ -59,8 +63,8 @@ namespace Microsoft.AspNetCore.Mvc
         public void IsValidAlwaysReturnsTrue()
         {
             // Act & Assert
-            Assert.True(new RemoteAttribute("RouteName", "ParameterName").IsValid(null));
+            Assert.True(new RemoteAttribute("RouteName", "ParameterName").IsValid(value: null));
-            Assert.True(new RemoteAttribute("ActionName", "ControllerName", "ParameterName").IsValid(null));
+            Assert.True(new RemoteAttribute("ActionName", "ControllerName", "ParameterName").IsValid(value: null));
         }
 
         [Fact]
@@ -155,6 +159,70 @@ namespace Microsoft.AspNetCore.Mvc
             Assert.Null(attribute.RouteName);
         }
 
+        [Fact]
+        public void ErrorMessageProperties_HaveExpectedDefaultValues()
+        {
+            // Arrange & Act
+            var attribute = new RemoteAttribute("Action", "Controller");
+
+            // Assert
+            Assert.Null(attribute.ErrorMessage);
+            Assert.Null(attribute.ErrorMessageResourceName);
+            Assert.Null(attribute.ErrorMessageResourceType);
+        }
+
+        [Fact]
+        [ReplaceCulture]
+        public void FormatErrorMessage_ReturnsDefaultErrorMessage()
+        {
+            // Arrange
+            // See ViewFeatures.Resources.RemoteAttribute_RemoteValidationFailed.
+            var expected = "'Property1' is invalid.";
+            var attribute = new RemoteAttribute("Action", "Controller");
+
+            // Act
+            var message = attribute.FormatErrorMessage("Property1");
+
+            // Assert
+            Assert.Equal(expected, message);
+        }
+
+        [Fact]
+        public void FormatErrorMessage_UsesOverriddenErrorMessage()
+        {
+            // Arrange
+            var expected = "Error about 'Property1' from override.";
+            var attribute = new RemoteAttribute("Action", "Controller")
+            {
+                ErrorMessage = "Error about '{0}' from override.",
+            };
+
+            // Act
+            var message = attribute.FormatErrorMessage("Property1");
+
+            // Assert
+            Assert.Equal(expected, message);
+        }
+
+        [Fact]
+        [ReplaceCulture]
+        public void FormatErrorMessage_UsesErrorMessageFromResource()
+        {
+            // Arrange
+            var expected = "Error about 'Property1' from resources.";
+            var attribute = new RemoteAttribute("Action", "Controller")
+            {
+                ErrorMessageResourceName = nameof(Resources.RemoteAttribute_Error),
+                ErrorMessageResourceType = typeof(Resources),
+            };
+
+            // Act
+            var message = attribute.FormatErrorMessage("Property1");
+
+            // Assert
+            Assert.Equal(expected, message);
+        }
+
         [Theory]
         [MemberData(nameof(NullOrEmptyNames))]
         public void FormatAdditionalFieldsForClientValidation_WithInvalidPropertyName_Throws(string property)
@@ -197,6 +265,7 @@ namespace Microsoft.AspNetCore.Mvc
         }
 
         [Fact]
+        [ReplaceCulture]
         public void AddValidation_WithRoute_CallsUrlHelperWithExpectedValues()
         {
             // Arrange
@@ -222,6 +291,7 @@ namespace Microsoft.AspNetCore.Mvc
         }
 
         [Fact]
+        [ReplaceCulture]
         public void AddValidation_WithActionController_CallsUrlHelperWithExpectedValues()
         {
             // Arrange
@@ -248,6 +318,7 @@ namespace Microsoft.AspNetCore.Mvc
         }
 
         [Fact]
+        [ReplaceCulture]
         public void AddValidation_WithActionController_PropertiesSet_CallsUrlHelperWithExpectedValues()
         {
             // Arrange
@@ -283,6 +354,294 @@ namespace Microsoft.AspNetCore.Mvc
         }
 
         [Fact]
+        public void AddValidation_WithErrorMessage_SetsAttributesAsExpected()
+        {
+            // Arrange
+            var expected = "Error about 'Length' from override.";
+            var attribute = new RemoteAttribute("Action", "Controller")
+            {
+                HttpMethod = "POST",
+                ErrorMessage = "Error about '{0}' from override.",
+            };
+            var url = "/Controller/Action";
+            var context = GetValidationContext(url);
+
+            // Act
+            attribute.AddValidation(context);
+
+            // Assert
+            Assert.Collection(
+                context.Attributes,
+                kvp => { Assert.Equal("data-val", kvp.Key); Assert.Equal("true", kvp.Value); },
+                kvp =>
+                {
+                    Assert.Equal("data-val-remote", kvp.Key);
+                    Assert.Equal(expected, kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("data-val-remote-additionalfields", kvp.Key);
+                    Assert.Equal("*.Length", kvp.Value);
+                },
+                kvp => { Assert.Equal("data-val-remote-type", kvp.Key); Assert.Equal("POST", kvp.Value); },
+                kvp => { Assert.Equal("data-val-remote-url", kvp.Key); Assert.Equal(url, kvp.Value); });
+        }
+
+        [Fact]
+        public void AddValidation_WithErrorMessageAndLocalizerFactory_SetsAttributesAsExpected()
+        {
+            // Arrange
+            var expected = "Error about 'Length' from override.";
+            var attribute = new RemoteAttribute("Action", "Controller")
+            {
+                HttpMethod = "POST",
+                ErrorMessage = "Error about '{0}' from override.",
+            };
+            var url = "/Controller/Action";
+            var context = GetValidationContextWithLocalizerFactory(url);
+
+            // Act
+            attribute.AddValidation(context);
+
+            // Assert
+            Assert.Collection(
+                context.Attributes,
+                kvp => { Assert.Equal("data-val", kvp.Key); Assert.Equal("true", kvp.Value); },
+                kvp =>
+                {
+                    // IStringLocalizerFactory existence alone is insufficient to change error message.
+                    Assert.Equal("data-val-remote", kvp.Key);
+                    Assert.Equal(expected, kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("data-val-remote-additionalfields", kvp.Key);
+                    Assert.Equal("*.Length", kvp.Value);
+                },
+                kvp => { Assert.Equal("data-val-remote-type", kvp.Key); Assert.Equal("POST", kvp.Value); },
+                kvp => { Assert.Equal("data-val-remote-url", kvp.Key); Assert.Equal(url, kvp.Value); });
+        }
+
+        [Fact]
+        public void AddValidation_WithErrorMessageAndLocalizerProvider_SetsAttributesAsExpected()
+        {
+            // Arrange
+            var expected = "Error about 'Length' from override.";
+            var attribute = new RemoteAttribute("Action", "Controller")
+            {
+                HttpMethod = "POST",
+                ErrorMessage = "Error about '{0}' from override.",
+            };
+            var url = "/Controller/Action";
+            var context = GetValidationContext(url);
+
+            var options = context.ActionContext.HttpContext.RequestServices
+                .GetRequiredService<IOptions<MvcDataAnnotationsLocalizationOptions>>();
+            var localizer = new Mock<IStringLocalizer>(MockBehavior.Strict);
+            options.Value.DataAnnotationLocalizerProvider = (type, factory) => localizer.Object;
+
+            // Act
+            attribute.AddValidation(context);
+
+            // Assert
+            Assert.Collection(
+                context.Attributes,
+                kvp => { Assert.Equal("data-val", kvp.Key); Assert.Equal("true", kvp.Value); },
+                kvp =>
+                {
+                    // Non-null DataAnnotationLocalizerProvider alone is insufficient to change error message.
+                    Assert.Equal("data-val-remote", kvp.Key);
+                    Assert.Equal(expected, kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("data-val-remote-additionalfields", kvp.Key);
+                    Assert.Equal("*.Length", kvp.Value);
+                },
+                kvp => { Assert.Equal("data-val-remote-type", kvp.Key); Assert.Equal("POST", kvp.Value); },
+                kvp => { Assert.Equal("data-val-remote-url", kvp.Key); Assert.Equal(url, kvp.Value); });
+        }
+
+        [Fact]
+        public void AddValidation_WithErrorMessageLocalizerFactoryAndLocalizerProvider_SetsAttributesAsExpected()
+        {
+            // Arrange
+            var expected = "Error about 'Length' from localizer.";
+            var attribute = new RemoteAttribute("Action", "Controller")
+            {
+                HttpMethod = "POST",
+                ErrorMessage = "Error about '{0}' from override.",
+            };
+            var url = "/Controller/Action";
+            var context = GetValidationContextWithLocalizerFactory(url);
+
+            var localizedString = new LocalizedString("Fred", expected);
+            var localizer = new Mock<IStringLocalizer>(MockBehavior.Strict);
+            localizer
+                .Setup(l => l["Error about '{0}' from override.", "Length"])
+                .Returns(localizedString)
+                .Verifiable();
+            var options = context.ActionContext.HttpContext.RequestServices
+                .GetRequiredService<IOptions<MvcDataAnnotationsLocalizationOptions>>();
+            options.Value.DataAnnotationLocalizerProvider = (type, factory) => localizer.Object;
+
+            // Act
+            attribute.AddValidation(context);
+
+            // Assert
+            localizer.VerifyAll();
+
+            Assert.Collection(
+                context.Attributes,
+                kvp => { Assert.Equal("data-val", kvp.Key); Assert.Equal("true", kvp.Value); },
+                kvp =>
+                {
+                    Assert.Equal("data-val-remote", kvp.Key);
+                    Assert.Equal(expected, kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("data-val-remote-additionalfields", kvp.Key);
+                    Assert.Equal("*.Length", kvp.Value);
+                },
+                kvp => { Assert.Equal("data-val-remote-type", kvp.Key); Assert.Equal("POST", kvp.Value); },
+                kvp => { Assert.Equal("data-val-remote-url", kvp.Key); Assert.Equal(url, kvp.Value); });
+        }
+
+        [Fact]
+        [ReplaceCulture]
+        public void AddValidation_WithErrorResourcesLocalizerFactoryAndLocalizerProvider_SetsAttributesAsExpected()
+        {
+            // Arrange
+            var expected = "Error about 'Length' from resources.";
+            var attribute = new RemoteAttribute("Action", "Controller")
+            {
+                HttpMethod = "POST",
+                ErrorMessageResourceName = nameof(Resources.RemoteAttribute_Error),
+                ErrorMessageResourceType = typeof(Resources),
+            };
+            var url = "/Controller/Action";
+            var context = GetValidationContextWithLocalizerFactory(url);
+
+            var localizer = new Mock<IStringLocalizer>(MockBehavior.Strict);
+            var options = context.ActionContext.HttpContext.RequestServices
+                .GetRequiredService<IOptions<MvcDataAnnotationsLocalizationOptions>>();
+            options.Value.DataAnnotationLocalizerProvider = (type, factory) => localizer.Object;
+
+            // Act
+            attribute.AddValidation(context);
+
+            // Assert
+            Assert.Collection(
+                context.Attributes,
+                kvp => { Assert.Equal("data-val", kvp.Key); Assert.Equal("true", kvp.Value); },
+                kvp =>
+                {
+                    // Configuring the attribute using ErrorMessageResource* trumps available IStringLocalizer etc.
+                    Assert.Equal("data-val-remote", kvp.Key);
+                    Assert.Equal(expected, kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("data-val-remote-additionalfields", kvp.Key);
+                    Assert.Equal("*.Length", kvp.Value);
+                },
+                kvp => { Assert.Equal("data-val-remote-type", kvp.Key); Assert.Equal("POST", kvp.Value); },
+                kvp => { Assert.Equal("data-val-remote-url", kvp.Key); Assert.Equal(url, kvp.Value); });
+        }
+
+        [Fact]
+        public void AddValidation_WithErrorMessageAndDisplayName_SetsAttributesAsExpected()
+        {
+            // Arrange
+            var expected = "Error about 'Display Length' from override.";
+            var attribute = new RemoteAttribute("Action", "Controller")
+            {
+                HttpMethod = "POST",
+                ErrorMessage = "Error about '{0}' from override.",
+            };
+
+            var url = "/Controller/Action";
+            var metadataProvider = new TestModelMetadataProvider();
+            metadataProvider
+                .ForProperty(typeof(string), nameof(string.Length))
+                .DisplayDetails(d => d.DisplayName = () => "Display Length");
+            var context = GetValidationContext(url, metadataProvider);
+
+            // Act
+            attribute.AddValidation(context);
+
+            // Assert
+            Assert.Collection(
+                context.Attributes,
+                kvp => { Assert.Equal("data-val", kvp.Key); Assert.Equal("true", kvp.Value); },
+                kvp =>
+                {
+                    Assert.Equal("data-val-remote", kvp.Key);
+                    Assert.Equal(expected, kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("data-val-remote-additionalfields", kvp.Key);
+                    Assert.Equal("*.Length", kvp.Value);
+                },
+                kvp => { Assert.Equal("data-val-remote-type", kvp.Key); Assert.Equal("POST", kvp.Value); },
+                kvp => { Assert.Equal("data-val-remote-url", kvp.Key); Assert.Equal(url, kvp.Value); });
+        }
+
+        [Fact]
+        public void AddValidation_WithErrorMessageLocalizerFactoryLocalizerProviderAndDisplayName_SetsAttributesAsExpected()
+        {
+            // Arrange
+            var expected = "Error about 'Length' from localizer.";
+            var attribute = new RemoteAttribute("Action", "Controller")
+            {
+                HttpMethod = "POST",
+                ErrorMessage = "Error about '{0}' from override.",
+            };
+
+            var url = "/Controller/Action";
+            var metadataProvider = new TestModelMetadataProvider();
+            metadataProvider
+                .ForProperty(typeof(string), nameof(string.Length))
+                .DisplayDetails(d => d.DisplayName = () => "Display Length");
+            var context = GetValidationContextWithLocalizerFactory(url, metadataProvider);
+
+            var localizedString = new LocalizedString("Fred", expected);
+            var localizer = new Mock<IStringLocalizer>(MockBehavior.Strict);
+            localizer
+                .Setup(l => l["Error about '{0}' from override.", "Display Length"])
+                .Returns(localizedString)
+                .Verifiable();
+            var options = context.ActionContext.HttpContext.RequestServices
+                .GetRequiredService<IOptions<MvcDataAnnotationsLocalizationOptions>>();
+            options.Value.DataAnnotationLocalizerProvider = (type, factory) => localizer.Object;
+
+            // Act
+            attribute.AddValidation(context);
+
+            // Assert
+            localizer.VerifyAll();
+
+            Assert.Collection(
+                context.Attributes,
+                kvp => { Assert.Equal("data-val", kvp.Key); Assert.Equal("true", kvp.Value); },
+                kvp =>
+                {
+                    Assert.Equal("data-val-remote", kvp.Key);
+                    Assert.Equal(expected, kvp.Value);
+                },
+                kvp =>
+                {
+                    Assert.Equal("data-val-remote-additionalfields", kvp.Key);
+                    Assert.Equal("*.Length", kvp.Value);
+                },
+                kvp => { Assert.Equal("data-val-remote-type", kvp.Key); Assert.Equal("POST", kvp.Value); },
+                kvp => { Assert.Equal("data-val-remote-url", kvp.Key); Assert.Equal(url, kvp.Value); });
+        }
+
+        [Fact]
+        [ReplaceCulture]
         public void AddValidation_WithActionControllerArea_CallsUrlHelperWithExpectedValues()
         {
             // Arrange
@@ -319,6 +678,7 @@ namespace Microsoft.AspNetCore.Mvc
 
         // Root area is current in this case.
         [Fact]
+        [ReplaceCulture]
         public void AddValidation_WithActionController_FindsControllerInCurrentArea()
         {
             // Arrange
@@ -343,6 +703,7 @@ namespace Microsoft.AspNetCore.Mvc
 
         // Test area is current in this case.
         [Fact]
+        [ReplaceCulture]
         public void AddValidation_WithActionControllerInArea_FindsControllerInCurrentArea()
         {
             // Arrange
@@ -368,6 +729,7 @@ namespace Microsoft.AspNetCore.Mvc
         // Explicit reference to the (current) root area.
         [Theory]
         [MemberData(nameof(NullOrEmptyNames))]
+        [ReplaceCulture]
         public void AddValidation_WithActionControllerArea_FindsControllerInRootArea(string areaName)
         {
             // Arrange
@@ -393,6 +755,7 @@ namespace Microsoft.AspNetCore.Mvc
         // Test area is current in this case.
         [Theory]
         [MemberData(nameof(NullOrEmptyNames))]
+        [ReplaceCulture]
         public void AddValidation_WithActionControllerAreaInArea_FindsControllerInRootArea(string areaName)
         {
             // Arrange
@@ -417,6 +780,7 @@ namespace Microsoft.AspNetCore.Mvc
 
         // Root area is current in this case.
         [Fact]
+        [ReplaceCulture]
         public void AddValidation_WithActionControllerArea_FindsControllerInNamedArea()
         {
             // Arrange
@@ -441,6 +805,7 @@ namespace Microsoft.AspNetCore.Mvc
 
         // Explicit reference to the current (Test) area.
         [Fact]
+        [ReplaceCulture]
         public void AddValidation_WithActionControllerAreaInArea_FindsControllerInNamedArea()
         {
             // Arrange
@@ -465,6 +830,7 @@ namespace Microsoft.AspNetCore.Mvc
 
         // Test area is current in this case.
         [Fact]
+        [ReplaceCulture]
         public void AddValidation_WithActionControllerAreaInArea_FindsControllerInDifferentArea()
         {
             // Arrange
@@ -518,35 +884,59 @@ namespace Microsoft.AspNetCore.Mvc
                 kvp => { Assert.Equal("data-val-remote-url", kvp.Key); Assert.Equal("original", kvp.Value); });
         }
 
-        private static ClientModelValidationContext GetValidationContext(IUrlHelper urlHelper)
+        private static ClientModelValidationContext GetValidationContext(
+            string url,
+            IModelMetadataProvider metadataProvider = null)
         {
-            var factory = new Mock<IUrlHelperFactory>();
+            var urlHelper = new MockUrlHelper(url, routeName: null);
+            return GetValidationContext(urlHelper, localizerFactory: null, metadataProvider: metadataProvider);
+        }
+
+        private static ClientModelValidationContext GetValidationContextWithLocalizerFactory(
+            string url,
+            IModelMetadataProvider metadataProvider = null)
+        {
+            var urlHelper = new MockUrlHelper(url, routeName: null);
+            var localizerFactory = new Mock<IStringLocalizerFactory>(MockBehavior.Strict);
+            return GetValidationContext(urlHelper, localizerFactory.Object, metadataProvider);
+        }
+
+        private static ClientModelValidationContext GetValidationContext(
+            IUrlHelper urlHelper,
+            IStringLocalizerFactory localizerFactory = null,
+            IModelMetadataProvider metadataProvider = null)
+        {
+            var serviceCollection = GetServiceCollection(localizerFactory);
+            var factory = new Mock<IUrlHelperFactory>(MockBehavior.Strict);
+            serviceCollection.AddSingleton<IUrlHelperFactory>(factory.Object);
+
+            var serviceProvider = serviceCollection.BuildServiceProvider();
+            var actionContext = GetActionContext(serviceProvider, routeData: null);
+
             factory
-                .Setup(f => f.GetUrlHelper(It.IsAny<ActionContext>()))
+                .Setup(f => f.GetUrlHelper(actionContext))
                 .Returns(urlHelper);
 
-            var serviceCollection = GetServiceCollection();
+            var metadata = _metadata;
-            serviceCollection.AddSingleton<IUrlHelperFactory>(factory.Object);
+            if (metadataProvider == null)
-            var serviceProvider = serviceCollection.BuildServiceProvider();
-
-            var actionContext = new ActionContext()
             {
-                HttpContext = new DefaultHttpContext()
+                metadataProvider = _metadataProvider;
-                {
+            }
-                    RequestServices = serviceProvider,
+            else
-                },
+            {
-            };
+                metadata = metadataProvider.GetMetadataForProperty(typeof(string), nameof(string.Length));
+            }
 
             return new ClientModelValidationContext(
                 actionContext,
-                _metadata,
+                metadata,
-                _metadataProvider,
+                metadataProvider,
                 new AttributeDictionary());
         }
 
         private static ClientModelValidationContext GetValidationContextWithArea(string currentArea)
         {
-            var serviceCollection = GetServiceCollection();
+            var serviceCollection = GetServiceCollection(localizerFactory: null);
             var serviceProvider = serviceCollection.BuildServiceProvider();
             var routeCollection = GetRouteCollectionWithArea(serviceProvider);
             var routeData = new RouteData
@@ -566,24 +956,18 @@ namespace Microsoft.AspNetCore.Mvc
                 routeData.Values["area"] = currentArea;
             }
 
-            var context = GetActionContext(serviceProvider, routeData);
+            var actionContext = GetActionContext(serviceProvider, routeData);
 
-            var urlHelper = new UrlHelper(context);
+            var urlHelper = new UrlHelper(actionContext);
-            var factory = new Mock<IUrlHelperFactory>();
+            var factory = new Mock<IUrlHelperFactory>(MockBehavior.Strict);
             factory
-                .Setup(f => f.GetUrlHelper(It.IsAny<ActionContext>()))
+                .Setup(f => f.GetUrlHelper(actionContext))
                 .Returns(urlHelper);
 
+            // Make an IUrlHelperFactory available through the ActionContext.
             serviceCollection.AddSingleton<IUrlHelperFactory>(factory.Object);
             serviceProvider = serviceCollection.BuildServiceProvider();
-
+            actionContext.HttpContext.RequestServices = serviceProvider;
-            var actionContext = new ActionContext()
-            {
-                HttpContext = new DefaultHttpContext()
-                {
-                    RequestServices = serviceProvider,
-                },
-            };
 
             return new ClientModelValidationContext(
                  actionContext,
@@ -615,7 +999,7 @@ namespace Microsoft.AspNetCore.Mvc
 
         private static RouteBuilder GetRouteBuilder(IServiceProvider serviceProvider)
         {
-            var app = new Mock<IApplicationBuilder>();
+            var app = new Mock<IApplicationBuilder>(MockBehavior.Strict);
             app
                 .SetupGet(a => a.ApplicationServices)
                 .Returns(serviceProvider);
@@ -631,9 +1015,7 @@ namespace Microsoft.AspNetCore.Mvc
             return builder;
         }
 
-        private static ActionContext GetActionContext(
+        private static ActionContext GetActionContext(IServiceProvider serviceProvider, RouteData routeData)
-            IServiceProvider serviceProvider,
-            RouteData routeData = null)
         {
             // Set IServiceProvider properties because TemplateRoute gets services (e.g. an ILoggerFactory instance)
             // through the HttpContext.
@@ -653,23 +1035,22 @@ namespace Microsoft.AspNetCore.Mvc
             return new ActionContext(httpContext, routeData, new ActionDescriptor());
         }
 
-        private static ServiceCollection GetServiceCollection()
+        private static ServiceCollection GetServiceCollection(IStringLocalizerFactory localizerFactory)
         {
             var serviceCollection = new ServiceCollection();
             serviceCollection.AddSingleton<ILoggerFactory>(new NullLoggerFactory());
             serviceCollection.AddSingleton<UrlEncoder>(new UrlTestEncoder());
 
-            var routeOptions = new RouteOptions();
+            serviceCollection.AddOptions();
-            var accessor = new Mock<IOptions<RouteOptions>>();
-            accessor
-                .SetupGet(options => options.Value)
-                .Returns(routeOptions);
-
-            serviceCollection.AddSingleton<IOptions<RouteOptions>>(accessor.Object);
             serviceCollection.AddRouting();
 
             serviceCollection.AddSingleton<IInlineConstraintResolver>(
-                new DefaultInlineConstraintResolver(accessor.Object));
+                provider => new DefaultInlineConstraintResolver(provider.GetRequiredService<IOptions<RouteOptions>>()));
+
+            if (localizerFactory != null)
+            {
+                serviceCollection.AddSingleton<IStringLocalizerFactory>(localizerFactory);
+            }
 
             return serviceCollection;
         }

test/Microsoft.AspNetCore.Mvc.ViewFeatures.Test/Resources.resx

@@ -126,4 +126,7 @@
   <data name="DisplayAttribute_Name" xml:space="preserve">
     <value>name from resources</value>
   </data>
+  <data name="RemoteAttribute_Error" xml:space="preserve">
+    <value>Error about '{0}' from resources.</value>
+  </data>
 </root>