python runtime_error ai_generated true

sqlalchemy.orm.exc.DetachedInstanceError: Instance <User at 0x...> is not bound to a Session; attribute refresh operation cannot proceed

ID: python/flask-sqlalchemy-detachedinstanceerror

Also available as: JSON · Markdown · 中文
80%Fix Rate
87%Confidence
0Evidence
2024-06-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
2.x active — — —
3.x active — — —

Root Cause

Accessing an attribute of an ORM object after the session that loaded it has been closed or committed.

generic

中文

在加载 ORM 对象的会话关闭或提交后访问该对象的属性。

Workarounds

  1. 90% success 
    user = session.query(User).options(joinedload(User.posts)).first()
# use user.posts before session.close()
  2. 85% success 
    Use `db.session` within the request context; avoid manual session.close().

Dead Ends

Common approaches that don't work:

  1. 60% fail

    This only prevents expiration on commit, not detachment after session close.

  2. 80% fail

    The session is already closed, so refresh fails.