diff --git a/modules/plugin_dbui/helper.py b/modules/plugin_dbui/helper.py
index d3629c78ca06e3d85c24b1fae19c34c9a04d730c..c9c1631556f5a61d9d587fe7f78378ac8c41b033 100644
--- a/modules/plugin_dbui/helper.py
+++ b/modules/plugin_dbui/helper.py
@@ -242,16 +242,14 @@ def get_foreign_field(field):
     # IS_IN_DB is not use. 
     # The parent key for the left join is the id key of the parent table
     # the parent field is the first field of the parent table which differs id
-    if not validators:
-        i = field.type.index(' ')
-        ktablename = field.type[i:].strip()
-        
-        for kfield in field._db[ktablename]:
-            if kfield.name != 'id':
-                return (ktablename, kfield.name, 'id')
-            
+    i = field.type.index(' ')
+    ktablename = field.type[i:].strip()
+    
+    for kfield in field._db[ktablename]:
+        if kfield.name != 'id':
+            return (ktablename, kfield.name, 'id')
 
-    return None
+    raise Exception
 
 
 def get_id(table, **kwargs):