Closes #22 and begins to address #23.

JSONAPI.Tests/Core/ModelManagerTests.cs

@@ -0,0 +1,44 @@
+using System;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using JSONAPI.Core;
+using JSONAPI.Tests.Models;
+using System.Reflection;
+
+namespace JSONAPI.Tests.Core
+{
+    [TestClass]
+    public class ModelManagerTests
+    {
+        private class InvalidModel
+        {
+            public string Data { get; set; }
+        }
+
+        [TestMethod]
+        public void FindsIdNamedId()
+        {
+            // Arrange
+            var mm = new ModelManager();
+
+            // Act
+            PropertyInfo idprop = mm.GetIdProperty(typeof(Author));
+
+            // Assert
+            Assert.AreSame(typeof(Author).GetProperty("Id"), idprop);
+        }
+
+        [TestMethod]
+        [ExpectedException(typeof(InvalidOperationException))]
+        public void DoesntFindMissingId()
+        {
+            // Arrange
+            var mm = new ModelManager();
+
+            // Act
+            PropertyInfo idprop = mm.GetIdProperty(typeof(InvalidModel));
+
+            // Assert
+            Assert.Fail("An InvalidOperationException should be thrown and we shouldn't get here!");
+        }
+    }
+}

JSONAPI.Tests/JSONAPI.Tests.csproj

@@ -77,6 +77,7 @@
   <ItemGroup>
     <Compile Include="ActionFilters\EnableFilteringAttributeTests.cs" />
     <Compile Include="Core\MetadataManagerTests.cs" />
+    <Compile Include="Core\ModelManagerTests.cs" />
     <Compile Include="Json\ErrorSerializerTests.cs" />
     <Compile Include="Json\JsonApiMediaFormaterTests.cs" />
     <Compile Include="Json\JsonHelpers.cs" />

JSONAPI/Core/IModelManager.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace JSONAPI.Core
+{
+    public interface IModelManager
+    {
+        PropertyInfo GetIdProperty(Type type);
+    }
+}

JSONAPI/Core/ModelManager.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace JSONAPI.Core
+{
+    public class ModelManager : IModelManager
+    {
+        public ModelManager() { }
+
+        #region Cache storage
+
+        private Lazy<Dictionary<Type, PropertyInfo>> _idProperties
+            = new Lazy<Dictionary<Type,PropertyInfo>>(
+                () => new Dictionary<Type, PropertyInfo>()
+            );
+
+        #endregion
+
+        #region Id property determination
+
+        public PropertyInfo GetIdProperty(Type type)
+        {
+            PropertyInfo idprop = null;
+
+            var idPropCache = _idProperties.Value;
+
+            lock (idPropCache)
+            {
+                if (idPropCache.TryGetValue(type, out idprop)) return idprop;
+
+                //TODO: Enable attribute-based determination
+
+                idprop = type.GetProperty("Id");
+
+                if (idprop == null)
+                    throw new InvalidOperationException(String.Format("Unable to determine Id property for type {0}", type));
+
+                idPropCache.Add(type, idprop);
+            }
+
+            return idprop;
+        }
+
+        #endregion
+    }
+}

JSONAPI/JSONAPI.csproj

@@ -68,9 +68,11 @@
     <Compile Include="Attributes\IncludeInPayload.cs" />
     <Compile Include="Attributes\LinkTemplate.cs" />
     <Compile Include="Attributes\SerializeAs.cs" />
+    <Compile Include="Core\IModelManager.cs" />
     <Compile Include="Core\IPluralizationService.cs" />
     <Compile Include="Core\IMaterializer.cs" />
     <Compile Include="Core\MetadataManager.cs" />
+    <Compile Include="Core\ModelManager.cs" />
     <Compile Include="Http\ApiController.cs" />
     <Compile Include="Json\ErrorSerializer.cs" />
     <Compile Include="Json\GuidErrorIdProvider.cs" />

JSONAPI/Json/JsonApiFormatter.cs

@@ -22,16 +22,23 @@ public class JsonApiFormatter : JsonMediaTypeFormatter
         public JsonApiFormatter()
             : this(new ErrorSerializer())
         {
+            if (_modelManager == null) _modelManager = new ModelManager();
+            SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/vnd.api+json"));
         }
 
         internal JsonApiFormatter(IErrorSerializer errorSerializer)
         {
             _errorSerializer = errorSerializer;
-            SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/vnd.api+json"));
         }
 
-        public IPluralizationService PluralizationService { get; set; }
+        public JsonApiFormatter(IModelManager modelManager) : this()
+        {
+            _modelManager = modelManager;
+        }
+
+        public IPluralizationService PluralizationService { get; set; } //FIXME: Deprecated, will be removed shortly
         private readonly IErrorSerializer _errorSerializer;
+        private readonly IModelManager _modelManager;
 
         private Lazy<Dictionary<Stream, RelationAggregator>> _relationAggregators
             = new Lazy<Dictionary<Stream, RelationAggregator>>(
@@ -152,7 +159,7 @@ protected void Serialize(object value, Stream writeStream, JsonWriter writer, Js
 
             // Do the Id now...
             writer.WritePropertyName("id");
-            var idProp = GetIdProperty(value.GetType());
+            var idProp = _modelManager.GetIdProperty(value.GetType());
             writer.WriteValue(GetValueForIdProperty(idProp, value));
 
             PropertyInfo[] props = value.GetType().GetProperties();
@@ -819,15 +826,17 @@ protected object GetById(Type type, string id)
         {
             // Only good for creating dummy relationship objects...
             object retval = Activator.CreateInstance(type);
-            PropertyInfo idprop = GetIdProperty(type);
+            PropertyInfo idprop = _modelManager.GetIdProperty(type);
             idprop.SetValue(retval, System.Convert.ChangeType(id, idprop.PropertyType));
             return retval;
         }
 
+        /*
         protected PropertyInfo GetIdProperty(Type type)
         {
             return type.GetProperty("Id");
         }
+        */
 
         protected string GetValueForIdProperty(PropertyInfo idprop, object obj)
         {
@@ -846,7 +855,7 @@ protected string GetValueForIdProperty(PropertyInfo idprop, object obj)
         protected string GetIdFor(object obj)
         {
             Type type = obj.GetType();
-            PropertyInfo idprop = GetIdProperty(type);
+            PropertyInfo idprop = _modelManager.GetIdProperty(type);
             return GetValueForIdProperty(idprop, obj);
         }