got unicode to do None...

diff --git a/lib/sqlalchemy/types.py b/lib/sqlalchemy/types.py
index 70d124ec86b5a3efe843b524b6e001ab931abeeb..fcd416398d1693cd751cba0e7581dccf2bd3065e 100644 (file)
--- a/lib/sqlalchemy/types.py
+++ b/lib/sqlalchemy/types.py
@@ -95,12 +95,12 @@ class String(NullTypeEngine):
         else:
             return self
     def convert_bind_param(self, value, engine):
-        if not engine.convert_unicode or not isinstance(value, unicode):
+        if not engine.convert_unicode or value is None or not isinstance(value, unicode):
             return value
         else:
             return value.encode('utf-8')
     def convert_result_value(self, value, engine):
-        if not engine.convert_unicode or isinstance(value, unicode):
+        if not engine.convert_unicode or value is None or isinstance(value, unicode):
             return value
         else:
             return value.decode('utf-8')