Fix RouteValueDictionary to handle read-only dictionaries.

src/Microsoft.AspNet.Routing/RouteValueDictionary.cs

@@ -23,7 +23,7 @@ namespace Microsoft.AspNet.Routing
         private readonly Dictionary<string, object> _dictionary;
 
         /// <summary>
-        /// Creates an empty RouteValueDictionary.
+        /// Creates an empty <see cref="RouteValueDictionary"/>.
         /// </summary>
         public RouteValueDictionary()
         {
@@ -31,28 +31,32 @@ namespace Microsoft.AspNet.Routing
         }
 
         /// <summary>
-        /// Creates a RouteValueDictionary initialized with the provided input values.
+        /// Creates a <see cref="RouteValueDictionary"/> initialized with the provided input value.
         /// </summary>
-        /// <param name="values">Input values to copy into the dictionary.</param>
+        /// <param name="obj">An object to initialize the dictionary. The value can be of type
-        public RouteValueDictionary([NotNull] IDictionary<string, object> values)
+        /// <see cref="IDictionary{TKey, TValue}"/> or <see cref="IReadOnlyDictionary{TKey, TValue}"/> or
-        {
+        /// any other object.
-            _dictionary = new Dictionary<string, object>(values, StringComparer.OrdinalIgnoreCase);
+        /// </param>
-        }
-
-        /// <summary>
-        /// Creates a RouteValueDictionary initialized with the provided input values.
-        /// </summary>
-        /// <param name="values">Input values to copy into the dictionary.</param>
         /// <remarks>
-        /// The input parameter is interpreted as a set of key-value-pairs where the property names
+        /// If the value is a dictionary, then its entries are copied. Otherwise the object is interpreted as a set
-        /// are keys, and property values are the values, and copied into the dictionary. Only public
+        /// of key-value-pairs where the property names are keys, and property values are the values, and copied
-        /// instance non-index properties are considered.
+        /// into the dictionary. Only public instance non-index properties are considered.
         /// </remarks>
         public RouteValueDictionary(object obj)
             : this()
         {
             if (obj != null)
             {
+                var keyValuePairCollection = obj as IEnumerable<KeyValuePair<string, object>>;
+                if (keyValuePairCollection != null)
+                {
+                    foreach (var kvp in keyValuePairCollection)
+                    {
+                        Add(kvp.Key, kvp.Value);
+                    }
+                    return;
+                }
+
                 var type = obj.GetType();
                 var allProperties = type.GetRuntimeProperties();
 

src/Microsoft.AspNet.Routing/Template/TemplateBinder.cs

@@ -370,11 +370,7 @@ namespace Microsoft.AspNet.Routing.Template
 
                 if (_defaults != null)
                 {
-                    _filters = new RouteValueDictionary(defaults);
+                    _filters = new RouteValueDictionary(_defaults);
-                    foreach (var kvp in _defaults)
-                    {
-                        _filters.Add(kvp.Key, kvp.Value);
-                    }
                 }
             }
 

test/Microsoft.AspNet.Routing.Tests/RouteValueDictionaryTests.cs

@@ -168,6 +168,48 @@ namespace Microsoft.AspNet.Routing.Tests
                 expected);
         }
 
+        [Fact]
+        public void CreateFromReadOnlyDictionary_CopiesValues()
+        {
+            // Arrange
+            var dictionary = new Dictionary<string, object>();
+            dictionary.Add("Name", "James");
+            dictionary.Add("Age", 30);
+            var readonlyDictionary = (IReadOnlyDictionary<string, object>)dictionary;
+
+            // Act
+            var dict = new RouteValueDictionary(readonlyDictionary);
+
+            // Assert
+            Assert.Equal(2, dict.Count);
+            Assert.Equal("James", dict["Name"]);
+            Assert.Equal(30, dict["Age"]);
+        }
+
+        [Fact]
+        public void CreateFromReadOnlyDictionary_ModifyRouteValueDictionary()
+        {
+            // Arrange
+            var dictionary = new Dictionary<string, object>();
+            dictionary.Add("Name", "James");
+            dictionary.Add("Age", 30);
+            dictionary.Add("Address", new Address() { City = "Redmond", State = "WA" });
+            var readonlyDictionary = (IReadOnlyDictionary<string, object>)dictionary;
+
+            // Act
+            var routeValueDictionary = new RouteValueDictionary(readonlyDictionary);
+            routeValueDictionary.Add("City", "Redmond");
+
+            // Assert
+            Assert.Equal(4, routeValueDictionary.Count);
+            Assert.Equal("James", routeValueDictionary["Name"]);
+            Assert.Equal(30, routeValueDictionary["Age"]);
+            Assert.Equal("Redmond", routeValueDictionary["City"]);
+            var address = Assert.IsType<Address>(routeValueDictionary["Address"]);
+            address.State = "Washington";
+            Assert.Equal("Washington", ((Address)routeValueDictionary["Address"]).State);
+        }
+
         private static string GetDuplicateKeyErrorMessage()
         {
             // Gets the exception message when duplicate entries are
@@ -233,5 +275,12 @@ namespace Microsoft.AspNet.Routing.Tests
                 set { }
             }
         }
+
+        private class Address
+        {
+            public string City { get; set; }
+
+            public string State { get; set; }
+        }
     }
 }