Add a custom collection type for ModelMetadata.Properties

This is a cleanup PR to improve the common usage of
ModelMetadata.Properties.

We found placed in code where both .Count and the ability to index by
property name would be useful. I was able to cascade this and simplify the
ModelBindingContext as well.

src/Microsoft.AspNet.Mvc.Core/Description/DefaultApiDescriptionProvider.cs

@@ -541,7 +541,6 @@ namespace Microsoft.AspNet.Mvc.Description
                 //  Order - source: Body
                 //
 
-                var propertyCount = 0;
                 var unboundProperties = new HashSet<ModelMetadata>();
 
                 // We don't want to append the **parameter** name when building a model name.
@@ -553,7 +552,6 @@ namespace Microsoft.AspNet.Mvc.Description
 
                 foreach (var propertyMetadata in modelMetadata.Properties)
                 {
-                    propertyCount++;
                     var key = new PropertyKey(propertyMetadata, source);
 
                     if (Visited.Add(key))
@@ -569,7 +567,7 @@ namespace Microsoft.AspNet.Mvc.Description
                     }
                 }
 
-                if (unboundProperties.Count == propertyCount)
+                if (unboundProperties.Count == modelMetadata.Properties.Count)
                 {
                     if (source == null || source == ambientSource)
                     {

src/Microsoft.AspNet.Mvc.Core/Rendering/Expressions/ExpressionMetadataProvider.cs

@@ -118,8 +118,7 @@ namespace Microsoft.AspNet.Mvc.Rendering.Expressions
             else
             {
                 //  Try getting a property from ModelMetadata if we couldn't find an answer in ViewData
-                var propertyMetadata =
+                var propertyMetadata = viewData.ModelMetadata.Properties[expression];
-                    viewData.ModelMetadata.Properties.Where(p => p.PropertyName == expression).FirstOrDefault();
                 if (propertyMetadata != null)
                 {
                     return propertyMetadata;

src/Microsoft.AspNet.Mvc.ModelBinding/Binders/MutableObjectModelBinder.cs

@@ -315,7 +315,7 @@ namespace Microsoft.AspNet.Mvc.ModelBinding
             foreach (var property in properties)
             {
                 var propertyName = property.Name;
-                var propertyMetadata = bindingContext.PropertyMetadata[propertyName];
+                var propertyMetadata = bindingContext.ModelMetadata.Properties[propertyName];
                 var requiredValidator = bindingContext.OperationBindingContext
                                                       .ValidatorProvider
                                                       .GetValidators(propertyMetadata)
@@ -366,7 +366,7 @@ namespace Microsoft.AspNet.Mvc.ModelBinding
                 // Update Model as SetProperty() would: Place null value where validator will check for non-null. This
                 // ensures a failure result from a required validator (if any) even for a non-nullable property.
                 // (Otherwise, propertyMetadata.Model is likely already null.)
-                var propertyMetadata = bindingContext.PropertyMetadata[missingRequiredProperty];
+                var propertyMetadata = bindingContext.ModelMetadata.Properties[missingRequiredProperty];
                 propertyMetadata.Model = null;
 
                 // Execute validator (if any) to get custom error message.

src/Microsoft.AspNet.Mvc.ModelBinding/Metadata/ModelMetadata.cs

@@ -28,7 +28,7 @@ namespace Microsoft.AspNet.Mvc.ModelBinding
         private Func<object> _modelAccessor;
         private int _order = DefaultOrder;
         private bool _isRequired;
-        private IEnumerable<ModelMetadata> _properties;
+        private ModelPropertyCollection _properties;
         private Type _realModelType;
         private string _simpleDisplayText;
 
@@ -193,14 +193,17 @@ namespace Microsoft.AspNet.Mvc.ModelBinding
 
         public virtual string NullDisplayText { get; set; }
 
-        public virtual IEnumerable<ModelMetadata> Properties
+        /// <summary>
+        /// Gets the collection of <see cref="ModelMetadata"/> instances for the model's properties.
+        /// </summary>
+        public virtual ModelPropertyCollection Properties
         {
             get
             {
                 if (_properties == null)
                 {
                     var properties = Provider.GetMetadataForProperties(Model, RealModelType);
-                    _properties = properties.OrderBy(m => m.Order).ToList();
+                    _properties = new ModelPropertyCollection(properties.OrderBy(m => m.Order));
                 }
 
                 return _properties;

src/Microsoft.AspNet.Mvc.ModelBinding/Metadata/ModelPropertyCollection.cs

@@ -0,0 +1,83 @@
+// Copyright (c) Microsoft Open Technologies, Inc. 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.Collections;
+using System.Collections.Generic;
+
+namespace Microsoft.AspNet.Mvc.ModelBinding
+{
+    /// <summary>
+    /// A read-only list of <see cref="ModelMetadata"/> objects which represent model properties.
+    /// </summary>
+    public class ModelPropertyCollection : IReadOnlyList<ModelMetadata>
+    {
+        private readonly List<ModelMetadata> _properties;
+
+        /// <summary>
+        /// Creates a new <see cref="ModelPropertyCollection"/>.
+        /// </summary>
+        /// <param name="properties">The properties.</param>
+        public ModelPropertyCollection([NotNull] IEnumerable<ModelMetadata> properties)
+        {
+            _properties = new List<ModelMetadata>(properties);
+        }
+
+        /// <inheritdoc />
+        public ModelMetadata this[int index]
+        {
+            get
+            {
+                return _properties[index];
+            }
+        }
+
+        /// <summary>
+        /// Gets a <see cref="ModelMetadata"/> instance for the property corresponding to <paramref name="propertyName"/>.
+        /// </summary>
+        /// <param name="propertyName">
+        /// The property name. Property names are compared using <see cref="StringComparison.Ordinal"/>
+        /// </param>
+        /// <returns>
+        /// The <see cref="ModelMetadata"/> instance for the property specified by <paramref name="propertyName"/>, or null
+        /// if no match can be found.
+        /// </returns>
+        public ModelMetadata this[[NotNull] string propertyName]
+        {
+
+            get
+            {
+                foreach (var property in _properties)
+                {
+                    if (string.Equals(property.PropertyName, propertyName, StringComparison.Ordinal))
+                    {
+                        return property;
+                    }
+                }
+
+                return null;
+            }
+        }
+
+        /// <inheritdoc />
+        public int Count
+        {
+            get
+            {
+                return _properties.Count;
+            }
+        }
+
+        /// <inheritdoc />
+        public IEnumerator<ModelMetadata> GetEnumerator()
+        {
+            return _properties.GetEnumerator();
+        }
+
+        /// <inheritdoc />
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
+    }
+}

src/Microsoft.AspNet.Mvc.ModelBinding/ModelBindingContext.cs

@@ -17,7 +17,6 @@ namespace Microsoft.AspNet.Mvc.ModelBinding
 
         private string _modelName;
         private ModelStateDictionary _modelState;
-        private Dictionary<string, ModelMetadata> _propertyMetadata;
         private ModelValidationNode _validationNode;
         private Func<ModelBindingContext, string, bool> _propertyFilter;
 
@@ -152,25 +151,6 @@ namespace Microsoft.AspNet.Mvc.ModelBinding
         /// </summary>
         public IValueProvider ValueProvider { get; set; }
 
-        /// <summary>
-        /// Gets a dictionary of property name to <see cref="ModelMetadata"/> instances for
-        /// <see cref="ModelMetadata.Properties"/>
-        /// </summary>
-        public IDictionary<string, ModelMetadata> PropertyMetadata
-        {
-            get
-            {
-                if (_propertyMetadata == null)
-                {
-                    _propertyMetadata = ModelMetadata.Properties
-                                                     .ToDictionary(m => m.PropertyName,
-                                                                   StringComparer.OrdinalIgnoreCase);
-                }
-
-                return _propertyMetadata;
-            }
-        }
-
         public Func<ModelBindingContext, string, bool> PropertyFilter
         {
             get

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/DefaultDisplayTemplatesTest.cs

@@ -141,8 +141,8 @@ namespace Microsoft.AspNet.Mvc.Core
 
             var model = new DefaultTemplatesUtilities.ObjectTemplateModel { Property1 = "p1", Property2 = null };
             var html = DefaultTemplatesUtilities.GetHtmlHelper(model);
-            var metadata =
+
-                html.ViewData.ModelMetadata.Properties.First(m => string.Equals(m.PropertyName, "Property1"));
+            var metadata = html.ViewData.ModelMetadata.Properties["Property1"];
             metadata.HideSurroundingHtml = true;
 
             // Act

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/DefaultEditorTemplatesTests.cs

@@ -187,8 +187,8 @@ Environment.NewLine;
 
             var model = new DefaultTemplatesUtilities.ObjectTemplateModel { Property1 = "p1", Property2 = null };
             var html = DefaultTemplatesUtilities.GetHtmlHelper(model);
-            var metadata =
+            
-                html.ViewData.ModelMetadata.Properties.First(m => string.Equals(m.PropertyName, "Property1"));
+            var metadata = html.ViewData.ModelMetadata.Properties["Property1"];
             metadata.HideSurroundingHtml = true;
 
             // Act
@@ -340,8 +340,8 @@ Environment.NewLine;
                 viewEngine.Object,
                 innerHelper => new StubbyHtmlHelper(innerHelper));
             helper.ViewData["Property1"] = "True";
-            var metadata =
+
-                helper.ViewData.ModelMetadata.Properties.First(m => string.Equals(m.PropertyName, "Property1"));
+            var metadata = helper.ViewData.ModelMetadata.Properties["Property1"];
             metadata.DataTypeName = templateName;
 
             // TemplateBuilder sets FormattedModelValue before calling TemplateRenderer and it's used in most templates.
@@ -372,8 +372,8 @@ Environment.NewLine;
                 model,
                 viewEngine.Object,
                 innerHelper => new StubbyHtmlHelper(innerHelper));
-            var metadata =
+
-                helper.ViewData.ModelMetadata.Properties.First(m => string.Equals(m.PropertyName, "Property1"));
+            var metadata = helper.ViewData.ModelMetadata.Properties["Property1"];
             metadata.DataTypeName = templateName;
 
             // TemplateBuilder sets FormattedModelValue before calling TemplateRenderer and it's used in most templates.
@@ -405,8 +405,8 @@ Environment.NewLine;
                 viewEngine.Object,
                 innerHelper => new StubbyHtmlHelper(innerHelper));
             helper.ViewData["Property1"] = "True";
-            var metadata =
+
-                helper.ViewData.ModelMetadata.Properties.First(m => string.Equals(m.PropertyName, "Property1"));
+            var metadata = helper.ViewData.ModelMetadata.Properties["Property1"];
             metadata.TemplateHint = templateName;
 
             // TemplateBuilder sets FormattedModelValue before calling TemplateRenderer and it's used in most templates.
@@ -437,8 +437,8 @@ Environment.NewLine;
                 model,
                 viewEngine.Object,
                 innerHelper => new StubbyHtmlHelper(innerHelper));
-            var metadata =
+
-                helper.ViewData.ModelMetadata.Properties.First(m => string.Equals(m.PropertyName, "Property1"));
+            var metadata = helper.ViewData.ModelMetadata.Properties["Property1"];
             metadata.TemplateHint = templateName;
 
             // TemplateBuilder sets FormattedModelValue before calling TemplateRenderer and it's used in most templates.

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/HtmlHelperDisplayNameExtensionsTest.cs

@@ -313,6 +313,7 @@ namespace Microsoft.AspNet.Mvc.Core
             {
                 MetadataProvider = new Mock<IModelMetadataProvider>();
                 Metadata = new Mock<ModelMetadata>(MetadataProvider.Object, null, null, typeof(object), null);
+                Metadata.SetupGet(m => m.Properties).CallBase();
 
                 MetadataProvider.Setup(p => p.GetMetadataForProperties(It.IsAny<object>(), It.IsAny<Type>()))
                     .Returns(new ModelMetadata[0]);

test/Microsoft.AspNet.Mvc.Core.Test/Rendering/HtmlHelperLabelExtensionsTest.cs

@@ -319,6 +319,7 @@ namespace Microsoft.AspNet.Mvc.Core
             {
                 MetadataProvider = new Mock<IModelMetadataProvider>();
                 Metadata = new Mock<ModelMetadata>(MetadataProvider.Object, null, null, typeof(object), null);
+                Metadata.SetupGet(m => m.Properties).CallBase();
 
                 MetadataProvider.Setup(p => p.GetMetadataForProperties(It.IsAny<object>(), It.IsAny<Type>()))
                     .Returns(new ModelMetadata[0]);

test/Microsoft.AspNet.Mvc.ModelBinding.Test/Metadata/CachedDataAnnotationsModelMetadataProviderTest.cs

@@ -185,7 +185,7 @@ namespace Microsoft.AspNet.Mvc.ModelBinding
             // Arrange
             var provider = new DataAnnotationsModelMetadataProvider();
             var metadata = provider.GetMetadataForType(modelAccessor: null, modelType: typeof(ClassWithHiddenProperties));
-            var property = metadata.Properties.First(m => string.Equals("DirectlyHidden", m.PropertyName));
+            var property = metadata.Properties["DirectlyHidden"];
 
             // Act
             var result = property.HideSurroundingHtml;
@@ -200,7 +200,7 @@ namespace Microsoft.AspNet.Mvc.ModelBinding
             // Arrange
             var provider = new DataAnnotationsModelMetadataProvider();
             var metadata = provider.GetMetadataForType(modelAccessor: null, modelType: typeof(ClassWithHiddenProperties));
-            var property = metadata.Properties.First(m => string.Equals("OfHiddenType", m.PropertyName));
+            var property = metadata.Properties["OfHiddenType"];
 
             // Act
             var result = property.HideSurroundingHtml;