Return empty change set

api/s4_tanks.py

@@ -21,11 +21,11 @@ def _get_tank(name: str, id: str) -> Row | None:
 
 def delete_tank(name: str, id: str) -> ChangeSet:
     if not is_tank(name, id):
-        return
+        return ChangeSet()
 
     row = _get_tank(name, id)
     if row == None:
-        return
+        return ChangeSet()
 
     elevation = row['elevation']
     init_level = row['init_level']
@@ -36,10 +36,10 @@ def delete_tank(name: str, id: str) -> ChangeSet:
     vol_curve = utility.decorate(row['vol_curve'], 'str', True)
     overflow = utility.decorate(row['overflow'], 'str', True)
 
-    sql += f"delete from tanks where id = '{id}';"
+    sql = f"delete from tanks where id = '{id}';"
     undo_sql = f'insert into tanks (id, elevation, init_level, min_level, max_level, diameter, min_vol, vol_curve, overflow) values ("{id}", {elevation}, {init_level}, {min_level}, {max_level}, {diameter}, {min_vol}, {vol_curve}, {overflow});'
 
-    return add_node(name, TANK, id, x, y, sql, undo_sql)
+    return delete_node(name, TANK, id, sql, undo_sql)
 
 
 def get_tank_elevation(name: str, id: str) -> float | None:
@@ -94,11 +94,11 @@ def get_tank_coord(name: str, id: str) -> dict[str, float] | None:
 
 def _set_tank(name: str, id: str, key: str, key_type: str, value: str, optional: bool = False) -> ChangeSet:
     if not is_tank(name, id):
-        return
+        return ChangeSet()
 
     row = _get_tank(name, id)
     if row == None:
-        return
+        return ChangeSet()
 
     return utility.update(name, TANK, 'tanks', 'id', id, key, key_type, row[key], value, optional)
 
@@ -129,7 +129,7 @@ def set_tank_min_vol(name: str, id: str, min_vol: float) -> ChangeSet:
 
 def set_tank_vol_curve(name: str, id: str, vol_curve: str) -> ChangeSet:
     if not is_curve(name, vol_curve):
-        return ChangeSet
+        return ChangeSet()
 
     return _set_tank(name, id, 'vol_curve', 'str', vol_curve, True)