def db_session_scope(
self,
engine: sqlalchemy.engine.Engine,
session_mode: t.Union[DBSessionScopeMode, str] = "rw"
) -> t.ContextManager[Session]:
"""Provide a transactional scope around a series of operations."""
is_ro = DBSessionScopeMode(
session_mode) == DBSessionScopeMode.READ_ONLY
session = Session(bind=engine, autoflush=False, autocommit=False)
def nonce(*args, **kwargs):
return None
if is_ro:
session.flush = nonce
session._flush = nonce
try:
yield session
if not is_ro:
session.commit()
except:
session.rollback()
raise
finally:
session.close()
def _flush(self, objects=None):
try:
print('>>>F ' + self.dbg_label)
return Session._flush(self, objects)
finally:
print('<<<F')
