fix: edge cases

Author: maurei

src/JsonApiDotNetCore/Middleware/IncomingTypeMatchFilter.cs

@@ -1,12 +1,12 @@
 using System;
+using System.Collections;
 using System.Linq;
 using System.Net.Http;
 using JsonApiDotNetCore.Configuration;
-using JsonApiDotNetCore.Controllers;
 using JsonApiDotNetCore.Errors;
-using JsonApiDotNetCore.Resources;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Filters;
+using Microsoft.EntityFrameworkCore.Internal;
 
 namespace JsonApiDotNetCore.Middleware
 {
@@ -37,7 +37,7 @@ public void OnActionExecuting(ActionExecutingContext context)
 
             if (request.Method == HttpMethods.Patch || request.Method == HttpMethods.Post)
             {
-                var deserializedType = context.ActionArguments.LastOrDefault().Value?.GetType();
+                var deserializedType = GetDeserializedType(context);
                 var expectedType = GetExpectedType();
 
                 if (deserializedType != null && expectedType != null && deserializedType != expectedType)
@@ -50,16 +50,26 @@ public void OnActionExecuting(ActionExecutingContext context)
             }
         }
 
-        private Type GetExpectedType()
+        private Type GetDeserializedType(ActionExecutingContext context)
         {
-            if (_jsonApiRequest.Kind == EndpointKind.Primary)
+            var deserializedValue = context.ActionArguments.LastOrDefault().Value;
+            
+            if (deserializedValue is IList resourceCollection && resourceCollection.Any())
             {
-                return _jsonApiRequest.PrimaryResource?.GetType();
+                return resourceCollection[0].GetType();
             }
-            else
+
+            return deserializedValue?.GetType();
+        }
+
+        private Type GetExpectedType()
+        {
+            if (_jsonApiRequest.Kind == EndpointKind.Primary)
             {
-                return _jsonApiRequest.SecondaryResource?.GetType();
+                return _jsonApiRequest.PrimaryResource.ResourceType;
             }
+            
+            return _jsonApiRequest.SecondaryResource?.ResourceType;
         }
 
         public void OnActionExecuted(ActionExecutedContext context) { /* noop */ }