Closes #22 and begins to address #23.

Author: SphtKr

JSONAPI.Tests/Core/ModelManagerTests.cs

@@ -0,0 +1,40 @@
+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
+            // Act
+            PropertyInfo idprop = ModelManager.Instance.GetIdProperty(typeof(Author));
+
+            // Assert
+            Assert.AreSame(typeof(Author).GetProperty("Id"), idprop);
+        }
+
+        [TestMethod]
+        [ExpectedException(typeof(InvalidOperationException))]
+        public void DoesntFindMissingId()
+        {
+            // Arrange
+            // Act
+            PropertyInfo idprop = ModelManager.Instance.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/ModelManager.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace JSONAPI.Core
+{
+    class ModelManager
+    {
+        #region Singleton pattern
+
+        private static readonly ModelManager instance = new ModelManager();
+
+        private ModelManager() { }
+
+        public static ModelManager Instance
+        {
+            get
+            {
+                return instance;
+            }
+        }
+
+        #endregion
+
+        #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;
+
+            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));
+
+            _idProperties.Value.Add(type, idprop);
+
+            return idprop;
+        }
+
+        #endregion
+    }
+}

JSONAPI/JSONAPI.csproj

@@ -71,6 +71,7 @@
     <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

@@ -152,7 +152,7 @@ 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.Instance.GetIdProperty(value.GetType());
             writer.WriteValue(GetValueForIdProperty(idProp, value));
 
             PropertyInfo[] props = value.GetType().GetProperties();
@@ -819,15 +819,17 @@ 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.Instance.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 +848,7 @@ protected string GetValueForIdProperty(PropertyInfo idprop, object obj)
         protected string GetIdFor(object obj)
         {
             Type type = obj.GetType();
-            PropertyInfo idprop = GetIdProperty(type);
+            PropertyInfo idprop = ModelManager.Instance.GetIdProperty(type);
             return GetValueForIdProperty(idprop, obj);
         }