fix: support for lazy loading proxies

src/JsonApiDotNetCore/Internal/ResourceGraph.cs

@@ -13,6 +13,7 @@ namespace JsonApiDotNetCore.Internal
     public class ResourceGraph : IResourceGraph
     {
         private List<ResourceContext> Resources { get; }
+        private static readonly Type proxyTargetAccessorType = Type.GetType("Castle.DynamicProxy.IProxyTargetAccessor, Castle.Core");
 
         public ResourceGraph(List<ResourceContext> resources)
         {
@@ -26,7 +27,9 @@ public ResourceContext GetResourceContext(string resourceName)
             => Resources.SingleOrDefault(e => e.ResourceName == resourceName);
         /// <inheritdoc />
         public ResourceContext GetResourceContext(Type resourceType)
-            => Resources.SingleOrDefault(e => e.ResourceType == resourceType);
+            => IsLazyLoadingProxyForResourceType(resourceType) ?
+                Resources.SingleOrDefault(e => e.ResourceType == resourceType.BaseType) :
+                Resources.SingleOrDefault(e => e.ResourceType == resourceType);
         /// <inheritdoc />
         public ResourceContext GetResourceContext<TResource>() where TResource : class, IIdentifiable
             => GetResourceContext(typeof(TResource));
@@ -121,10 +124,13 @@ private IEnumerable<IResourceField> Getter<T>(Expression<Func<T, dynamic>> selec
             }
 
             throw new ArgumentException(
-                $"The expression '{selector}' should select a single property or select multiple properties into an anonymous type. " + 
+                $"The expression '{selector}' should select a single property or select multiple properties into an anonymous type. " +
                 $"For example: 'article => article.Title' or 'article => new {{ article.Title, article.PageCount }}'.");
         }
 
+        private bool IsLazyLoadingProxyForResourceType(Type resourceType) =>
+            proxyTargetAccessorType?.IsAssignableFrom(resourceType) ?? false;
+
         private static Expression RemoveConvert(Expression expression)
             => expression is UnaryExpression unaryExpression
                && unaryExpression.NodeType == ExpressionType.Convert

test/UnitTests/Internal/ResourceGraphBuilder_Tests.cs

@@ -1,9 +1,11 @@
 using JsonApiDotNetCore.Builders;
 using JsonApiDotNetCore.Configuration;
 using JsonApiDotNetCore.Internal;
+using JsonApiDotNetCore.Models;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
+using Castle.DynamicProxy;
 using Xunit;
 
 namespace UnitTests.Internal
@@ -41,12 +43,47 @@ public void Adding_DbContext_Members_That_Do_Not_Implement_IIdentifiable_Logs_Wa
             Assert.Equal("Entity 'UnitTests.Internal.ResourceGraphBuilder_Tests+TestContext' does not implement 'IIdentifiable'.", loggerFactory.Logger.Messages[0].Text);
         }
 
+        [Fact]
+        public void GetResourceContext_Yields_Right_Type_For_LazyLoadingProxy()
+        {
+            // Arrange
+            var resourceGraphBuilder = new ResourceGraphBuilder(new JsonApiOptions(), NullLoggerFactory.Instance);
+            resourceGraphBuilder.AddResource<Bar>();
+            var resourceGraph = (ResourceGraph)resourceGraphBuilder.Build();
+            var proxyGenerator = new ProxyGenerator();
+
+            // Act
+            var proxy = proxyGenerator.CreateClassProxy<Bar>();
+            var result = resourceGraph.GetResourceContext(proxy.GetType());
+
+            // Assert
+            Assert.Equal(typeof(Bar), result.ResourceType);
+        }
+
+        [Fact]
+        public void GetResourceContext_Yields_Right_Type_For_Identifiable()
+        {
+            // Arrange
+            var resourceGraphBuilder = new ResourceGraphBuilder(new JsonApiOptions(), NullLoggerFactory.Instance);
+            resourceGraphBuilder.AddResource<Bar>();
+            var resourceGraph = (ResourceGraph)resourceGraphBuilder.Build();
+
+            // Act
+            var result = resourceGraph.GetResourceContext(typeof(Bar));
+
+            // Assert
+            Assert.Equal(typeof(Bar), result.ResourceType);
+        }
+
         private class Foo { }
 
         private class TestContext : DbContext
         {
             public DbSet<Foo> Foos { get; set; }
         }
+
+        public class Bar : Identifiable { }
+
     }
 
 }

test/UnitTests/UnitTests.csproj

@@ -16,6 +16,7 @@
   <ItemGroup>
     <PackageReference Include="Bogus" Version="$(BogusVersion)" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="$(EFCoreVersion)" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Proxies" Version="$(EFCoreVersion)" />
     <PackageReference Include="Moq" Version="$(MoqVersion)" />
     <PackageReference Include="xunit" Version="$(XUnitVersion)" />
     <PackageReference Include="xunit.runner.visualstudio" Version="$(XUnitVersion)" />