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SqlAlchemy: get object instance state

This: Intro to object states lists the four permutations of presence-in-DB/presence-in-session:

transient, pending, persistent & detached

Is there any way of querying a given object to return which of the four states the object 开发者_如何学运维is in?

I tried rooting around in _sa_instance_state but couldn't find anything relevant.

Thanks!


[Update: This answer is for versions before 0.8]

Found it 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) 


Better use Inspection API:

from sqlalchemy import inspect
state = inspect(obj)

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


Another option is object_state, retuning an 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


another option, which lists ALL objects in particular states within a session: 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
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