SqlAlchemy:获取对象实例状态

Question

这:对象状态简介列出了存在于数据库中/存在于会话中的四种排列:

transient, pending, persistent & detached

是否有任何方法可以查询给定对象以返回对象所处的四种状态中的哪一种？

我尝试过根,_sa_instance_state但找不到任何相关的东西.

谢谢!

Answer 1

[更新:此答案适用于0.8之前的版本]

在这里找到它:

from sqlalchemy.orm import object_session 
from sqlalchemy.orm.util import has_identity 

# transient: 
object_session(obj) is None and not has_identity(obj) 
# pending: 
object_session(obj) is not None and not has_identity(obj) 
# detached: 
object_session(obj) is None and has_identity(obj) 
# persistent: 
object_session(obj) is not None and has_identity(obj) 

Answer 2

更好地使用Inspection API:

from sqlalchemy import inspect
state = inspect(obj)

# Booleans
state.transient
state.pending
state.detached
state.persistent

Answer 3

另一个选项是object_state，重新调整InstanceState：

from sqlalchemy.orm.util import object_state

state = object_state(obj)
# here are the four states:
state.transient  # !session & !identity_key
state.pending    #  session & !identity_key
state.persistent #  session &  identity_key
state.detached   # !session &  identity_key
# and low-level attrs
state.identity_key
state.has_identity # bool(identity_key)
state.session