processModelAsArray by PK

src/SaveRelationsBehavior.php

@@ -168,6 +168,14 @@ class SaveRelationsBehavior extends Behavior
         if (is_array($data)) {
             $fks = [];
             
+            // search PK
+            foreach($modelClass::primaryKey() as $modelAttribute) {
+                if (array_key_exists($modelAttribute, $data) && !empty($data[$modelAttribute])) {
+                    $fks[$modelAttribute] = $data[$modelAttribute];
+                }
+            }
+
+            if (!$fks) {
                 // Get the right link definition
                 if ($relation->via instanceof BaseActiveRecord) {
                     $viaQuery = $relation->via;
@@ -184,6 +192,7 @@ class SaveRelationsBehavior extends Behavior
                         $fks[$modelAttribute] = $data[$modelAttribute];
                     }
                 }
+            }
         } else {
             $fks = $data;
         }