Merge pull request #18716 from RodrigoDornelles/patch-1

use getTargetClass in function checkTargetAttributeExistence

framework/validators/ExistValidator.php

@@ -169,7 +169,7 @@ private function checkTargetAttributeExistence($model, $attribute)
             $conditions[] = $params;
         }
 
-        $targetClass = $this->targetClass === null ? get_class($model) : $this->targetClass;
+        $targetClass = $this->getTargetClass($model);
         $query = $this->createQuery($targetClass, $conditions);
 
         if (!$this->valueExists($targetClass, $query, $model->$attribute)) {