fix model building

Author: genusP

src/Microsoft.AspNet.OData.Shared/Builder/EdmModelHelperMethods.cs

@@ -176,6 +176,7 @@ private static string ConvertBindingPath(EdmTypeMap edmMap, NavigationPropertyBi
             {
                 Type typeCast = TypeHelper.AsType(bindingInfo);
                 PropertyInfo propertyInfo = bindingInfo as PropertyInfo;
+                MethodInfo methodInfo = bindingInfo as MethodInfo;
 
                 if (typeCast != null)
                 {
@@ -187,6 +188,11 @@ private static string ConvertBindingPath(EdmTypeMap edmMap, NavigationPropertyBi
                     PropertyDescriptor propDescr = new PropertyDescriptor(propertyInfo);
                     bindings.Add(edmMap.EdmProperties[propDescr].Name);
                 }
+                else if (methodInfo != null)
+                {
+                    PropertyDescriptor propDescr = new PropertyDescriptor(methodInfo);
+                    bindings.Add(edmMap.EdmProperties[propDescr].Name);
+                }
             }
 
             return String.Join("/", bindings);

src/Microsoft.AspNet.OData.Shared/Builder/NavigationSourceConfiguration.cs

@@ -7,6 +7,7 @@
 using System.Diagnostics.Contracts;
 using System.Linq;
 using System.Reflection;
+using System.Runtime.CompilerServices;
 using Microsoft.AspNet.OData.Common;
 
 namespace Microsoft.AspNet.OData.Builder
@@ -525,8 +526,8 @@ private void VerifyBindingPath(NavigationPropertyConfiguration navigationConfigu
             Contract.Assert(navigationConfiguration != null);
             Contract.Assert(bindingPath != null);
 
-            PropertyInfo navigation = bindingPath.Last() as PropertyInfo;
-            if (navigation == null || navigation != navigationConfiguration.PropertyInfo)
+            MemberInfo navigation = bindingPath.Last() as MemberInfo;
+            if (navigation == null || navigation != navigationConfiguration.PropertyInfo.MemberInfo)
             {
                 throw Error.Argument("navigationConfiguration", SRResources.NavigationPropertyBindingPathIsNotValid,
                     bindingPath.ConvertBindingPath(), navigationConfiguration.Name);
@@ -552,13 +553,25 @@ private static Type VerifyBindingSegment(Type current, MemberInfo info)
                 return derivedType.BaseType;
             }
 
+            Type declaringType = null;
+            Type propertyType = null;
             PropertyInfo propertyInfo = info as PropertyInfo;
-            if (propertyInfo == null)
+            MethodInfo methodInfo = info as MethodInfo;
+            if(propertyInfo!=null)
+            {
+                declaringType = info.DeclaringType;
+                propertyType = propertyInfo.PropertyType;
+            }
+            else if(methodInfo!=null && methodInfo.GetCustomAttribute<ExtensionAttribute>()!=null)
+            {
+                declaringType = methodInfo.GetParameters().First().ParameterType;
+                propertyType = methodInfo.ReturnType;
+            }
+            else
             {
                 throw Error.NotSupported(SRResources.NavigationPropertyBindingPathNotSupported, info.Name, info.MemberType);
             }
 
-            Type declaringType = propertyInfo.DeclaringType;
             if (declaringType == null ||
                 !(declaringType.IsAssignableFrom(current) || current.IsAssignableFrom(declaringType)))
             {
@@ -567,12 +580,12 @@ private static Type VerifyBindingSegment(Type current, MemberInfo info)
             }
 
             Type elementType;
-            if (TypeHelper.IsCollection(propertyInfo.PropertyType, out elementType))
+            if (TypeHelper.IsCollection(propertyType, out elementType))
             {
                 return elementType;
             }
 
-            return propertyInfo.PropertyType;
+            return propertyType;
         }
     }
 }