fixed error message on empty target_metadata _script undefined

diff --git a/alembic/autogenerate.py b/alembic/autogenerate.py
index 8fc51920b7da99733c11ab81f6b4f806ce245578..d0a5e736cb8edd22b8a03ee6d1a7790cc8c47528 100644 (file)
--- a/alembic/autogenerate.py
+++ b/alembic/autogenerate.py
@@ -21,7 +21,7 @@ def produce_migration_diffs(context, template_args, imports):
                 "Can't proceed with --autogenerate option; environment "
                 "script %s does not provide "
                 "a MetaData object to the context." % (
-                    context._script.env_py_location
+                    context.script.env_py_location
                 ))
     connection = context.bind
     diffs = []