Rework `ViewDataDictionary` constructors to ensure `ModelMetadata` is never `null`
- `ViewDataDictionary<TModel>` constructors now pass `typeof(TModel)` to base `protected` constructors - move type compatibility checks into base `ViewDataDictionary` - remove `ViewDataDictionary<TModel>.ModelMetadata` override - don't retrieve `ModelMetadata` twice in a single constructor invocation - remove newly-unused `protected` properties and use `private` fields in copy constructors Address longstanding problems found (see #1466) - avoid reusing `ModelMetadata` after `Model` value changes - reset `ModelMetadata` backing field in `Model` setter - `Model` and `ModelMetadata.Model` could previously get out of sync - carry `ModelMetadata` forward from an outer scope only if `Model` matches - previously two scopes could have different `Model` values but share their `ModelMetadata` (and `ModelMetadata.Model`) - related to previous item but didn't require `Model` setting; switching to a property of the same type as containing `Model` was enough - avoid NRE if `ViewDataDictionary<int>.Model` is read before it's written - problem affected all non-`Nullable` value types - `ViewDataDictionary.ModelMetadata` setter should throw if value is `null` nits: - add and reword doc and code comments - `ViewDataDictionary<TModel>` constructors should only inherit base's parameter descriptions; have more information in the derived class - make a few `ViewDataDictionary` properties get-only - clean up `using` statements in `ViewDataDictionary<TModel>` - make two constructors `internal`
This commit is contained in:
Doug Bunting
parent
83187945d1
commit
a3b07dacdb
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@ -4,4 +4,6 @@
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using System.Runtime.CompilerServices;
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[assembly: InternalsVisibleTo("Microsoft.AspNet.Mvc.Core.Test")]
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[assembly: InternalsVisibleTo("Microsoft.AspNet.Mvc.Razor.Test")]
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[assembly: InternalsVisibleTo("Microsoft.AspNet.Mvc.TagHelpers.Test")]
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[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")]
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@ -14,78 +14,238 @@ namespace Microsoft.AspNet.Mvc
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public class ViewDataDictionary : IDictionary<string, object>
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{
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private readonly IDictionary<string, object> _data;
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private readonly Type _declaredModelType;
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private readonly IModelMetadataProvider _metadataProvider;
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private object _model;
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private ModelMetadata _modelMetadata;
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private IModelMetadataProvider _metadataProvider;
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public ViewDataDictionary([NotNull] IModelMetadataProvider metadataProvider)
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/// <summary>
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/// Initializes a new instance of the <see cref="ViewDataDictionary"/> class.
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/// </summary>
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/// <param name="metadataProvider">
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/// <see cref = "IModelMetadataProvider" /> instance used to calculate
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/// <see cref="ViewDataDictionary.ModelMetadata"/> values.
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/// </param>
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/// <param name="modelState"><see cref="ModelStateDictionary"/> instance for this scope.</param>
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/// <remarks>For use when creating a <see cref="ViewDataDictionary"/> for a new top-level scope.</remarks>
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public ViewDataDictionary([NotNull] IModelMetadataProvider metadataProvider,
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[NotNull] ModelStateDictionary modelState)
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: this(metadataProvider, modelState, declaredModelType: typeof(object))
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{
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="ViewDataDictionary"/> class based entirely on an existing
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/// instance.
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/// </summary>
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/// <param name="source"><see cref="ViewDataDictionary"/> instance to copy initial values from.</param>
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/// <remarks>
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/// For use when copying a <see cref="ViewDataDictionary"/> instance and the declared <see cref="Model"/>
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/// <see cref="Type"/> will not change e.g. when copying from a <see cref="ViewDataDictionary{TModel}"/>
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/// instance to a base <see cref="ViewDataDictionary"/> instance.
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/// </remarks>
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public ViewDataDictionary([NotNull] ViewDataDictionary source)
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: this(source, source.Model, source._declaredModelType)
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{
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="ViewDataDictionary"/> class based in part on an existing
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/// instance. This constructor is careful to avoid exceptions <see cref="SetModel"/> may throw when
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/// <paramref name="model"/> is <c>null</c>.
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/// </summary>
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/// <param name="source"><see cref="ViewDataDictionary"/> instance to copy initial values from.</param>
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/// <param name="model">Value for the <see cref="Model"/> property.</param>
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/// <remarks>
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/// For use when the new instance's declared <see cref="Model"/> <see cref="Type"/> is unknown but its
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/// <see cref="Model"/> is known. In this case, <see cref="object"/> is the best possible guess about the
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/// declared type when <paramref name="model"/> is <c>null</c>.
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/// </remarks>
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public ViewDataDictionary([NotNull] ViewDataDictionary source, object model)
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: this(source, model, declaredModelType: typeof(object))
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{
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="ViewDataDictionary"/> class.
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/// </summary>
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/// <param name="metadataProvider">
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/// <see cref="IModelMetadataProvider"/> instance used to calculate
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/// <see cref="ViewDataDictionary.ModelMetadata"/> values.
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/// </param>
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/// <remarks>Internal for testing.</remarks>
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internal ViewDataDictionary([NotNull] IModelMetadataProvider metadataProvider)
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: this(metadataProvider, new ModelStateDictionary())
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{
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}
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public ViewDataDictionary([NotNull] IModelMetadataProvider metadataProvider,
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[NotNull] ModelStateDictionary modelState)
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/// <summary>
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/// Initializes a new instance of the <see cref="ViewDataDictionary"/> class.
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/// </summary>
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/// <param name="metadataProvider">
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/// <see cref = "IModelMetadataProvider" /> instance used to calculate
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/// <see cref="ViewDataDictionary.ModelMetadata"/> values.
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/// </param>
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/// <param name="declaredModelType">
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/// <see cref="Type"/> of <see cref="Model"/> values expected. Used to set
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/// <see cref="ViewDataDictionary.ModelMetadata"/> when <see cref="Model"/> is <c>null</c>.
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/// </param>
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/// <remarks>
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/// For use when creating a derived <see cref="ViewDataDictionary"/> for a new top-level scope.
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/// </remarks>
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protected ViewDataDictionary(
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[NotNull] IModelMetadataProvider metadataProvider,
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[NotNull] Type declaredModelType)
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: this(metadataProvider, new ModelStateDictionary(), declaredModelType)
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{
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="ViewDataDictionary"/> class.
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/// </summary>
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/// <param name="metadataProvider">
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/// <see cref = "IModelMetadataProvider" /> instance used to calculate
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/// <see cref="ViewDataDictionary.ModelMetadata"/> values.
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/// </param>
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/// <param name="modelState"><see cref="ModelStateDictionary"/> instance for this scope.</param>
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/// <param name="declaredModelType">
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/// <see cref="Type"/> of <see cref="Model"/> values expected. Used to set
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/// <see cref="ViewDataDictionary.ModelMetadata"/> when <see cref="Model"/> is <c>null</c>.
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/// </param>
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/// <remarks>
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/// For use when creating a derived <see cref="ViewDataDictionary"/> for a new top-level scope.
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/// </remarks>
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protected ViewDataDictionary(
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[NotNull] IModelMetadataProvider metadataProvider,
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[NotNull] ModelStateDictionary modelState,
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[NotNull] Type declaredModelType)
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: this(metadataProvider,
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modelState: modelState,
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modelState,
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declaredModelType,
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data: new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase),
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templateInfo: new TemplateInfo())
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{
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// This is the core constructor called when Model is unknown. Base ModelMetadata on the declared type.
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ModelMetadata = _metadataProvider.GetMetadataForType(() => null, _declaredModelType);
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}
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/// <summary>
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/// <see cref="ViewDataDictionary"/> copy constructor for use when model type does not change or caller will
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/// immediately set the <see cref="Model"/> property.
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/// Initializes a new instance of the <see cref="ViewDataDictionary"/> class based in part on an existing
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/// instance.
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/// </summary>
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public ViewDataDictionary([NotNull] ViewDataDictionary source)
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: this(source, source.Model)
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/// <param name="source"><see cref="ViewDataDictionary"/> instance to copy initial values from.</param>
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/// <param name="declaredModelType">
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/// <see cref="Type"/> of <see cref="Model"/> values expected. Used to set
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/// <see cref="ViewDataDictionary.ModelMetadata"/> when <see cref="Model"/> is <c>null</c>.
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/// </param>
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/// <remarks>
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/// <para>
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/// For use when copying a <see cref="ViewDataDictionary"/> instance and new instance's declared
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/// <see cref="Model"/> <see cref="Type"/> is known but <see cref="Model"/> should be copied from the existing
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/// instance e.g. when copying from a base <see cref="ViewDataDictionary"/> instance to a
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/// <see cref="ViewDataDictionary{TModel}"/> instance.
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/// </para>
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/// <para>
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/// This constructor may <c>throw</c> if <c>source.Model</c> is non-<c>null</c> and incompatible with
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/// <paramref name="declaredModelType"/>. Pass <c>model: null</c> to
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/// <see cref="ViewDataDictionary(ViewDataDictionary, object, Type)"/> to ignore <c>source.Model</c>.
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/// </para>
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/// </remarks>
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protected ViewDataDictionary([NotNull] ViewDataDictionary source, Type declaredModelType)
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: this(source, model: source.Model, declaredModelType: declaredModelType)
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{
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}
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/// <summary>
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/// <see cref="ViewDataDictionary"/> copy constructor for use when model type may change. This avoids
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/// exceptions a derived class may throw when <see cref="SetModel"/> is called.
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/// Initializes a new instance of the <see cref="ViewDataDictionary"/> class based in part on an existing
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/// instance. This constructor is careful to avoid exceptions <see cref="SetModel"/> may throw when
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/// <paramref name="model"/> is <c>null</c>.
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/// </summary>
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public ViewDataDictionary([NotNull] ViewDataDictionary source, object model)
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: this(source.MetadataProvider,
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/// <param name="source"><see cref="ViewDataDictionary"/> instance to copy initial values from.</param>
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/// <param name="model">Value for the <see cref="Model"/> property.</param>
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/// <param name="declaredModelType">
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/// <see cref="Type"/> of <see cref="Model"/> values expected. Used to set
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/// <see cref="ViewDataDictionary.ModelMetadata"/> when <see cref="Model"/> is <c>null</c>.
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/// </param>
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/// <remarks>
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/// <para>
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/// For use when copying a <see cref="ViewDataDictionary"/> instance and new instance's declared
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/// <see cref="Model"/> <see cref="Type"/> and <see cref="Model"/> are known.
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/// </para>
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/// <para>
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/// This constructor may <c>throw</c> if <paramref name="model"/> is non-<c>null</c> and incompatible with
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/// <paramref name="declaredModelType"/>.
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/// </para>
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/// </remarks>
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protected ViewDataDictionary([NotNull] ViewDataDictionary source, object model, Type declaredModelType)
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: this(source._metadataProvider,
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new ModelStateDictionary(source.ModelState),
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new CopyOnWriteDictionary<string, object>(source, StringComparer.OrdinalIgnoreCase),
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new TemplateInfo(source.TemplateInfo))
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declaredModelType,
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data: new CopyOnWriteDictionary<string, object>(source, StringComparer.OrdinalIgnoreCase),
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templateInfo: new TemplateInfo(source.TemplateInfo))
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{
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// Avoid copying information about the object type. To do so when model==null would confuse the
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// ViewDataDictionary<TModel>.ModelMetadata getter.
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if (source.ModelMetadata?.ModelType != typeof(object))
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// This is the core constructor called when Model is known.
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var modelType = GetModelType(model);
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if (modelType == source.ModelMetadata.ModelType && model == source.ModelMetadata.Model)
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{
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_modelMetadata = source.ModelMetadata;
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// Preserve any customizations made to source.ModelMetadata if the Type that will be calculated in
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// SetModel() and source.Model match new instance's values.
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ModelMetadata = source.ModelMetadata;
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}
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else if (model == null)
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{
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// Ensure ModelMetadata is never null though SetModel() isn't called.
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ModelMetadata = _metadataProvider.GetMetadataForType(() => null, _declaredModelType);
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}
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// If we're constructing a derived ViewDataDictionary<TModel> where TModel is a non-Nullable value type,
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// SetModel will throw if we try to call it with null. We should not throw in that case.
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// If we're constructing a ViewDataDictionary<TModel> where TModel is a non-Nullable value type,
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// SetModel() will throw if we try to call it with null. We should not throw in that case.
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if (model != null)
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{
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SetModel(model);
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}
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}
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private ViewDataDictionary(IModelMetadataProvider metadataProvider,
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ModelStateDictionary modelState,
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IDictionary<string, object> data,
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TemplateInfo templateInfo)
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private ViewDataDictionary(
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IModelMetadataProvider metadataProvider,
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ModelStateDictionary modelState,
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Type declaredModelType,
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IDictionary<string, object> data,
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TemplateInfo templateInfo)
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{
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_metadataProvider = metadataProvider;
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ModelState = modelState;
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_declaredModelType = declaredModelType;
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_data = data;
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TemplateInfo = templateInfo;
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}
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public object Model
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{
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get { return _model; }
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set { SetModel(value); }
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get
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{
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return _model;
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}
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set
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{
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// Reset ModelMetadata to ensure Model and ModelMetadata.Model remain equal.
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_modelMetadata = null;
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SetModel(value);
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}
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}
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public ModelStateDictionary ModelState { get; private set; }
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public ModelStateDictionary ModelState { get; }
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public virtual ModelMetadata ModelMetadata
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/// <summary>
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/// <see cref="ModelMetadata"/> for the current <see cref="Model"/> value or the declared <see cref="Type"/> if
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/// <see cref="Model"/> is <c>null</c>.
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/// </summary>
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/// <remarks>
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/// Value is never <c>null</c> but may describe the <see cref="object"/> class in some cases. This may for
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/// example occur in controllers if <see cref="Model"/> is <c>null</c>.
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/// </remarks>
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public ModelMetadata ModelMetadata
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{
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get
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{
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@ -93,19 +253,18 @@ namespace Microsoft.AspNet.Mvc
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}
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set
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{
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if (value == null)
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{
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throw new ArgumentNullException(Resources.FormatPropertyOfTypeCannotBeNull(
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nameof(ViewDataDictionary.ModelMetadata),
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nameof(ViewDataDictionary)));
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}
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_modelMetadata = value;
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}
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}
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public TemplateInfo TemplateInfo { get; private set; }
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/// <summary>
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/// Provider for subclasses that need it to override <see cref="ModelMetadata"/>.
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/// </summary>
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protected IModelMetadataProvider MetadataProvider
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{
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get { return _metadataProvider; }
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}
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public TemplateInfo TemplateInfo { get; }
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#region IDictionary properties
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// Do not just pass through to _data: Indexer should not throw a KeyNotFoundException.
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@ -194,19 +353,46 @@ namespace Microsoft.AspNet.Mvc
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// enough so as not to depend on the "this" pointer referencing a fully constructed object.
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protected virtual void SetModel(object value)
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{
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EnsureCompatible(value);
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_model = value;
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if (value == null)
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// Reset or override ModelMetadata based on runtime value type. Fall back to declared type if value is
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// null. When called from the Model setter, ModelMetadata will (temporarily) be null. When called from
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// a constructor, current ModelMetadata may already be set to preserve customizations made in parent scope.
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var modelType = GetModelType(value);
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if (ModelMetadata == null || ModelMetadata.ModelType != modelType)
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{
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// Unable to determine model metadata.
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_modelMetadata = null;
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ModelMetadata = _metadataProvider.GetMetadataForType(() => value, modelType);
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}
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else if (_modelMetadata == null || value.GetType() != ModelMetadata.ModelType)
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}
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// Throw if given value is incompatible with the declared Model Type.
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private void EnsureCompatible(object value)
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{
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// IsCompatibleObject verifies if the value is either an instance of _declaredModelType or (if value is
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// null) that _declaredModelType is a nullable type.
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var castWillSucceed = _declaredModelType.IsCompatibleWith(value);
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if (!castWillSucceed)
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{
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// Reset or override model metadata based on new value type.
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_modelMetadata = _metadataProvider.GetMetadataForType(() => value, value.GetType());
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string message;
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if (value == null)
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{
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message = Resources.FormatViewData_ModelCannotBeNull(_declaredModelType);
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}
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else
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{
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message = Resources.FormatViewData_WrongTModelType(value.GetType(), _declaredModelType);
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}
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throw new InvalidOperationException(message);
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}
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}
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private Type GetModelType(object value)
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{
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return (value == null) ? _declaredModelType : value.GetType();
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}
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#region IDictionary methods
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public void Add([NotNull] string key, object value)
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{
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|
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@ -1,88 +1,89 @@
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// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
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// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
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using System;
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using Microsoft.AspNet.Mvc.Core;
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using Microsoft.AspNet.Mvc.ModelBinding;
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namespace Microsoft.AspNet.Mvc
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{
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public class ViewDataDictionary<TModel> : ViewDataDictionary
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{
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// Fallback ModelMetadata based on TModel. Used when Model is null and base ViewDataDictionary class is unable
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// to determine the correct metadata.
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private readonly ModelMetadata _defaultModelMetadata;
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/// <inheritdoc />
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public ViewDataDictionary([NotNull] IModelMetadataProvider metadataProvider)
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: base(metadataProvider)
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: base(metadataProvider, declaredModelType: typeof(TModel))
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{
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_defaultModelMetadata = MetadataProvider.GetMetadataForType(null, typeof(TModel));
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}
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public ViewDataDictionary([NotNull] IModelMetadataProvider metadataProvider,
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// References may not show up due to ITypeActivator use in RazorPageActivator.
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/// <summary>
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/// Initializes a new instance of the <see cref="ViewDataDictionary{TModel}"/> class.
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/// </summary>
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/// <remarks>
|
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/// For use when creating a <see cref="ViewDataDictionary{TModel}"/> for a new top-level scope.
|
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/// </remarks>
|
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/// <inheritdoc />
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public ViewDataDictionary(
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[NotNull] IModelMetadataProvider metadataProvider,
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[NotNull] ModelStateDictionary modelState)
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: base(metadataProvider, modelState)
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: base(metadataProvider, modelState, declaredModelType: typeof(TModel))
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{
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}
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// References may not show up due to ITypeActivator use in RazorPageActivator.
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/// <summary>
|
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/// Initializes a new instance of the <see cref="ViewDataDictionary{TModel}"/> class based in part on an
|
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/// existing <see cref="ViewDataDictionary"/> instance.
|
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/// </summary>
|
||||
/// <remarks>
|
||||
/// <para>
|
||||
/// For use when copying a <see cref="ViewDataDictionary"/> instance and <typeparamref name="TModel"/> is known
|
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/// but <see cref="Model"/> should be copied from the existing instance e.g. when copying from a base
|
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/// <see cref="ViewDataDictionary"/> instance to a <see cref="ViewDataDictionary{TModel}"/> instance.
|
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/// </para>
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/// <para>
|
||||
/// This constructor may <c>throw</c> if <c>source.Model</c> is non-<c>null</c> and incompatible with
|
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/// <typeparamref name="TModel"/>. Pass <c>model: null</c> to
|
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/// <see cref="ViewDataDictionary{TModel}(ViewDataDictionary, object)"/> to ignore <c>source.Model</c>.
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/// </para>
|
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/// </remarks>
|
||||
/// <inheritdoc />
|
||||
public ViewDataDictionary([NotNull] ViewDataDictionary source)
|
||||
: this(source, source.Model)
|
||||
: base(source, declaredModelType: typeof(TModel))
|
||||
{
|
||||
}
|
||||
|
||||
// Model parameter type is object to allow "model: null" calls even when TModel is a value type. A TModel
|
||||
// parameter would likely require IEquatable<TModel> type restrictions to pass expected null value to the base
|
||||
// constructor.
|
||||
/// <summary>
|
||||
/// Initializes a new instance of the <see cref="ViewDataDictionary{TModel}"/> class based in part on an
|
||||
/// existing <see cref="ViewDataDictionary"/> instance. This constructor is careful to avoid exceptions
|
||||
/// <see cref="ViewDataDictionary.SetModel"/> may throw when <paramref name="model"/> is <c>null</c>.
|
||||
/// </summary>
|
||||
/// <remarks>
|
||||
/// <para>
|
||||
/// For use when copying a <see cref="ViewDataDictionary"/> instance and <typeparamref name="TModel"/> and
|
||||
/// <see cref="Model"/> are known.
|
||||
/// </para>
|
||||
/// <para>
|
||||
/// This constructor may <c>throw</c> if <paramref name="model"/> is non-<c>null</c> and incompatible with
|
||||
/// <typeparamref name="TModel"/>.
|
||||
/// </para>
|
||||
/// </remarks>
|
||||
/// <inheritdoc />
|
||||
public ViewDataDictionary([NotNull] ViewDataDictionary source, object model)
|
||||
: base(source, model)
|
||||
: base(source, model, declaredModelType: typeof(TModel))
|
||||
{
|
||||
var original = source as ViewDataDictionary<TModel>;
|
||||
if (original != null)
|
||||
{
|
||||
_defaultModelMetadata = original._defaultModelMetadata;
|
||||
}
|
||||
else
|
||||
{
|
||||
_defaultModelMetadata = MetadataProvider.GetMetadataForType(null, typeof(TModel));
|
||||
}
|
||||
}
|
||||
|
||||
public new TModel Model
|
||||
{
|
||||
get { return (TModel)base.Model; }
|
||||
set { SetModel(value); }
|
||||
}
|
||||
|
||||
public override ModelMetadata ModelMetadata
|
||||
{
|
||||
get
|
||||
{
|
||||
return base.ModelMetadata ?? _defaultModelMetadata;
|
||||
return (base.Model == null) ? default(TModel) : (TModel)base.Model;
|
||||
}
|
||||
}
|
||||
|
||||
protected override void SetModel(object value)
|
||||
{
|
||||
// IsCompatibleObject verifies if the value is either an instance of TModel or (if value is null) that
|
||||
// TModel is a nullable type.
|
||||
var castWillSucceed = typeof(TModel).IsCompatibleWith(value);
|
||||
|
||||
if (castWillSucceed)
|
||||
set
|
||||
{
|
||||
base.SetModel(value);
|
||||
}
|
||||
else
|
||||
{
|
||||
string message;
|
||||
if (value == null)
|
||||
{
|
||||
message = Resources.FormatViewData_ModelCannotBeNull(typeof(TModel));
|
||||
}
|
||||
else
|
||||
{
|
||||
message = Resources.FormatViewData_WrongTModelType(value.GetType(), typeof(TModel));
|
||||
}
|
||||
|
||||
throw new InvalidOperationException(message);
|
||||
base.Model = value;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
|
|
|||
Loading…
Reference in New Issue