Allow non-id primary key

src/ModeResolver/IdsModeResolver.php

@@ -30,15 +30,33 @@ public function resolve($property, &$object, &$root, $fullPropertyPath)
             // model, because the first item returned was a property
             // We therefore just return the single ID
             if (Utility::isPrimitive($firstElement)) {
-                return (int) Utility::getProperty($object, 'id');
+								$return = Utility::getProperty($object, $entry->getKeyName());
+
+                if ($entry->incrementing){
+									return (int) $return;
+								}
+
+								return $return;
             }
 
             return array_map(function ($entry) {
-                return (int) Utility::getProperty($entry, 'id');
+								$return = Utility::getProperty($entry, $entry->getKeyName());
+
+                if ($entry->incrementing){
+									return (int) $return;
+								}
+
+								return $return;
             }, $object);
         } elseif ($object instanceof Collection) {
             return $object->map(function ($entry) {
-                return (int) Utility::getProperty($entry, 'id');
+								$return = Utility::getProperty($entry, $entry->getKeyName());
+
+                if ($entry->incrementing){
+									return (int) $return;
+								}
+
+								return $return;
             });
         // The relation is not a collection, but rather
         // a singular relation

src/ModeResolver/SideloadModeResolver.php

@@ -102,13 +102,13 @@ private function mergeRootCollection(&$collection, $object)
      */
     private function addResourceToRootCollectionIfNonExistant(&$collection, $resource)
     {
-        $identifier = Utility::getProperty($resource, 'id');
+        $identifier = Utility::getProperty($resource, $resource->getKeyName());
         $exists = false;
 
         $copy = $collection instanceof Collection ? $collection->toArray() : $collection;
 
         foreach ($copy as $rootResource) {
-            if ((int) Utility::getProperty($rootResource, 'id') === (int) $identifier) {
+            if (Utility::getProperty($rootResource, $resource->getKeyName()) == $identifier) {
                 $exists = true;
                 break;
             }

src/Utility.php

@@ -18,7 +18,8 @@ public static function getProperty($objectOrArray, $property)
         if (is_array($objectOrArray)) {
             return $objectOrArray[$property];
         } else {
-            return $objectOrArray->{$property};
+            return $objectOrArray->getAttributes()[$property];
+            // return $objectOrArray->{$property};
         }
     }