diff --git a/model/SqlResultProvider.php b/model/SqlResultProvider.php
index cae4e77..4fd28b3 100644
--- a/model/SqlResultProvider.php
+++ b/model/SqlResultProvider.php
@@ -72,7 +72,8 @@ class SqlResultProvider
 
     public function getKeys()
     {
-        return array_keys($this->result);
+        $this->defineResultItems();
+        return array_keys($this->result_items);
     }
 
     /**
@@ -112,4 +113,4 @@ class SqlResultProvider
     {
         return $this->result->affectedRows();
     }
-}
\ No newline at end of file
+}