#38 - Provide a default dictionary for HttpContext.Items that returns null for missing values.

src/Microsoft.AspNet.PipelineCore/Collections/ItemsDictionary.cs

@@ -0,0 +1,111 @@
+using System.Collections;
+using System.Collections.Generic;
+using Microsoft.AspNet.Abstractions;
+
+namespace Microsoft.AspNet.PipelineCore
+{
+    public class ItemsDictionary : IDictionary<object, object>
+    {
+        public ItemsDictionary()
+            : this(new Dictionary<object, object>())
+        {
+        }
+
+        public ItemsDictionary(IDictionary<object, object> items)
+        {
+            Items = items;
+        }
+
+        public IDictionary<object, object> Items { get; private set; }
+
+        // Replace the indexer with one that returns null for missing values
+        object IDictionary<object, object>.this[object key]
+        {
+            get
+            {
+                object value;
+                if (Items.TryGetValue(key, out value))
+                {
+                    return value;
+                }
+                return null;
+            }
+            set { Items[key] = value; }
+        }
+
+        void IDictionary<object, object>.Add(object key, object value)
+        {
+            Items.Add(key, value);
+        }
+
+        bool IDictionary<object, object>.ContainsKey(object key)
+        {
+            return Items.ContainsKey(key);
+        }
+
+        ICollection<object> IDictionary<object, object>.Keys
+        {
+            get { return Items.Keys; }
+        }
+
+        bool IDictionary<object, object>.Remove(object key)
+        {
+            return Items.Remove(key);
+        }
+
+        bool IDictionary<object, object>.TryGetValue(object key, out object value)
+        {
+            return Items.TryGetValue(key, out value);
+        }
+
+        ICollection<object> IDictionary<object, object>.Values
+        {
+            get { return Items.Values; }
+        }
+
+        void ICollection<KeyValuePair<object, object>>.Add(KeyValuePair<object, object> item)
+        {
+            Items.Add(item);
+        }
+
+        void ICollection<KeyValuePair<object, object>>.Clear()
+        {
+            Items.Clear();
+        }
+
+        bool ICollection<KeyValuePair<object, object>>.Contains(KeyValuePair<object, object> item)
+        {
+            return Items.Contains(item);
+        }
+
+        void ICollection<KeyValuePair<object, object>>.CopyTo(KeyValuePair<object, object>[] array, int arrayIndex)
+        {
+            Items.CopyTo(array, arrayIndex);
+        }
+
+        int ICollection<KeyValuePair<object, object>>.Count
+        {
+            get { return Items.Count; }
+        }
+
+        bool ICollection<KeyValuePair<object, object>>.IsReadOnly
+        {
+            get { return Items.IsReadOnly; }
+        }
+
+        bool ICollection<KeyValuePair<object, object>>.Remove(KeyValuePair<object, object> item)
+        {
+            return Items.Remove(item);
+        }
+
+        IEnumerator<KeyValuePair<object, object>> IEnumerable<KeyValuePair<object, object>>.GetEnumerator()
+        {
+            return Items.GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return Items.GetEnumerator();
+        }
+    }
+}

src/Microsoft.AspNet.PipelineCore/DefaultCanHasItems.cs

@@ -6,7 +6,7 @@ namespace Microsoft.AspNet.PipelineCore
     {
         public DefaultCanHasItems()
         {
-            Items = new Dictionary<object, object>();
+            Items = new ItemsDictionary();
         }
 
         public IDictionary<object, object> Items { get; private set; }

src/Microsoft.AspNet.PipelineCore/Microsoft.AspNet.PipelineCore.kproj

@@ -23,6 +23,7 @@
     <Compile Include="Builder.cs" />
     <Compile Include="Collections\FormCollection.cs" />
     <Compile Include="Collections\HeaderDictionary.cs" />
+    <Compile Include="Collections\ItemsDictionary.cs" />
     <Compile Include="Collections\ReadableStringCollection.cs" />
     <Compile Include="Collections\RequestCookiesCollection.cs" />
     <Compile Include="Collections\ResponseCookies.cs" />