SQLAlchemy的：获取对象实例的状态

Question

此：Intro to object states列出的四种置换的存在，在-DB /在场的会期：

transient, pending, persistent & detached 

是否有查询给定对象的任何方式返回其中对象在四个状态？

我试过在_sa_instance_state附近生根，但找不到任何相关的东西。

谢谢！

Answer 1

更好地利用Inspection API：

from sqlalchemy import inspect 
state = inspect(obj) 

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

Answer 2

[更新：这个答案是0.8之前的版本]

发现here：

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 3

另一种选择，其中列出了一个会话内特定国家所有对象： http://docs.sqlalchemy.org/en/latest/orm/session.html#session-attributes

# pending objects recently added to the Session 
session.new 

# persistent objects which currently have changes detected 
# (this collection is now created on the fly each time the property is called) 
session.dirty 

# persistent objects that have been marked as deleted via session.delete(obj) 
session.deleted 

# dictionary of all persistent objects, keyed on their 
# identity key 
session.identity_map 

Answer 4

另一种选择是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