diff --git a/app/controllers/api/databases.php b/app/controllers/api/databases.php
index 2e11630e05..fdb986b155 100644
--- a/app/controllers/api/databases.php
+++ b/app/controllers/api/databases.php
@@ -1622,8 +1622,8 @@ App::post('/v1/databases/:databaseId/collections/:collectionId/attributes/relati
             throw new Exception(Exception::DATABASE_NOT_FOUND);
         }
 
-        $collectionDocument = $dbForProject->getDocument('database_' . $database->getInternalId(), $collectionId);
-        $collection = $dbForProject->getCollection('database_' . $database->getInternalId() . '_collection_' . $collectionDocument->getInternalId());
+        $collection = $dbForProject->getDocument('database_' . $database->getInternalId(), $collectionId);
+        $collection = $dbForProject->getCollection('database_' . $database->getInternalId() . '_collection_' . $collection->getInternalId());
 
         if ($collection->isEmpty()) {
             throw new Exception(Exception::COLLECTION_NOT_FOUND);