imgrey ha scritto:
> Good Day sqlalchemy.
>
> I was searching, but didn't found a way to delete records from db not
> executing selection first.
>
You must istantiate an istance of the obj to be deleted.
This is an Object Manager, so all operation is available on object.
or you can execute a plain string-sql direclty from engine
connection = engine.connect()
connection.execute("DELETE FROM a WHERE b = c")
> So, how to represent this SQL statement in slqalchemy ORM :
> """ DELETE FROM a WHERE b = c """ ?
>
> not it look like this :
> stuff = session.query(A).select_from(a_table).filter(A.c.b==c).first()
> session.delete(stuff)
>
>
> P.S.
>
> How to understand the following :
>
> Traceback (most recent call
> last):
> File "threading.py", line 442, in
> __bootstrap
>
> self.run()
> File "./camper.py", line 173, in
> run
>
> session.delete(stuff)
> File "/usr/lib/python2.4/site-packages/sqlalchemy/orm/scoping.py",
> line 74, in
>
> do
> return getattr(self.registry(), name)(*args,
> **kwargs)
> File "/usr/lib/python2.4/site-packages/sqlalchemy/orm/session.py",
> line 849, i
> n
> delete
>
> self._delete_impl(object)
> File "/usr/lib/python2.4/site-packages/sqlalchemy/orm/session.py",
> line 1007,
> in
> _delete_impl
> raise exceptions.InvalidRequestError("Instance '%s' is not
> persisted" % mapp
> erutil.instance_str(obj))
> InvalidRequestError: Instance '[EMAIL PROTECTED]' is not persisted
>
>
seems your object is not attached to session.
>
> It occurs sometimes in threaded application in this code :
>
> """
> from sqlalchemy.orm import mapper, relation, backref, create_session,
> scoped_session
> session = scoped_session(create_session)
> stuff =
> session.query(Path).select_from(f_table.join(u_table)).filter(User.c.id==theone.id).first()
> session.delete(stuff)
> """
>
>
i don't use scoped_session.
but try instead
stuff.delete()
Glauco
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