diff --git a/gluon/dal.py b/gluon/dal.py
index f8579a70..9d18eb11 100644
--- a/gluon/dal.py
+++ b/gluon/dal.py
@@ -74,10 +74,10 @@ def _default_validators(db, field):
         return requires
     if field.unique:
         requires.append(validators.IS_NOT_IN_DB(db, field))
-    sff = ['in', 'do', 'da', 'ti', 'de', 'bo']
-    if field.notnull and not field_type[:2] in sff:
-        requires.append(validators.IS_NOT_EMPTY())
-    elif not field.notnull and field_type[:2] in sff and requires:
+    
+    if field.notnull or field.unique:
+        requires.insert(0,validators.IS_NOT_EMPTY())
+    elif not field.notnull and requires:
         requires[0] = validators.IS_EMPTY_OR(requires[0])
     return requires