fix: support for lazy loading proxies

Author: mrnkr

src/JsonApiDotNetCore/Internal/ResourceGraph.cs

@@ -26,7 +26,7 @@ public ResourceContext GetResourceContext(string resourceName)
             => Resources.SingleOrDefault(e => e.ResourceName == resourceName);
         /// <inheritdoc />
         public ResourceContext GetResourceContext(Type resourceType)
-            => Resources.SingleOrDefault(e => e.ResourceType == resourceType);
+            => Resources.SingleOrDefault(e => e.ResourceType == resourceType) ?? Resources.SingleOrDefault(e => e.ResourceType.IsAssignableFrom(resourceType));
         /// <inheritdoc />
         public ResourceContext GetResourceContext<TResource>() where TResource : class, IIdentifiable
             => GetResourceContext(typeof(TResource));

test/UnitTests/Internal/ResourceGraphBuilder_Tests.cs

@@ -1,6 +1,8 @@
+using System;
 using JsonApiDotNetCore.Builders;
 using JsonApiDotNetCore.Configuration;
 using JsonApiDotNetCore.Internal;
+using JsonApiDotNetCore.Models;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
@@ -41,12 +43,48 @@ 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_Proxy()
+        {
+            // Arrange
+            var resourceGraphBuilder = new ResourceGraphBuilder(new JsonApiOptions(), NullLoggerFactory.Instance);
+            resourceGraphBuilder.AddResource<Bar>();
+            var resourceGraph = (ResourceGraph)resourceGraphBuilder.Build();
+
+            // Act
+            var result = resourceGraph.GetResourceContext(typeof(DummyProxy));
+
+            // Assert
+            Assert.Equal(typeof(Bar), result.ResourceType);
+        }
+
+        [Fact]
+        public void GetResourceContext_Yields_Right_Type_For_IIdentifiable()
+        {
+            // 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; }
         }
+
+        private class Bar : Identifiable { }
+
+        // Used to simulate a lazy loading proxy
+        private class DummyProxy : Bar { }
+
     }
 
 }