Make use of change set

api/s1_title.py

@@ -1,13 +1,14 @@
 from psycopg.rows import dict_row
 from .operation import *
 from .connection import g_conn_dict as conn
+from .change_set import ChangeSet
 
 def get_title(name: str) -> str:
     with conn[name].cursor(row_factory=dict_row) as cur:
         cur.execute(f"select * from title")
         return cur.fetchone()['value']
 
-def set_title(name: str, value: str) -> None:
+def set_title(name: str, value: str) -> ChangeSet:
     old = get_title(name)
 
     with conn[name].cursor() as cur:
@@ -17,3 +18,7 @@ def set_title(name: str, value: str) -> None:
         redo = sql.replace("'", '"')
         undo = f'update title set value = "{old}"'
         add_operation(name, redo, undo)
+
+    change = ChangeSet()
+    change.update('title', 'null', 'value')
+    return change