Okay I see. That does remove the error. But I am having trouble saving
the relationship. Check the example code. It is much clearer than I am.
If I query a new set of items or specify an item model instance it will
save perfectly. But all of the instances in the instrumented list will not
save to the relationship. Is there a further expiration step?
# This works
session.expire(model, ['items'])
make_transient(model)
model.items = ItemModel.query.all() # [<ItemModel>]
session.add(model)
session.commit()
Test.query.first().items # [<ItemModel>]
# This does not save
items = model.items.copy() # [<ItemModel>]
session.expire(model, ['items'])
make_transient(model)
model.items = items
session.add(model)
session.commit()
Test.query.first().items # []
On Thursday, October 27, 2016 at 6:15:39 PM UTC-4, Mike Bayer wrote:
>
> you'd say:
>
> session.expire(model, ["items"])
>
>
>
> On 10/27/2016 04:47 PM, Colton Allen wrote:
> > Sorry I must have combined multiple attempts into one example. When you
> > say expire the relationship, what do you mean?
> >
> >
> > On Thursday, October 27, 2016 at 4:30:36 PM UTC-4, Mike Bayer wrote:
> >
> > Hello -
> >
> >
> > I've rebuilt your fragment into a full example in order to determine
> > what the behavior is here, as make_transient() has no defined
> behavior
> > for loaded relationships.
> >
> > Your error does not reproduce with your code fragment as given,
> because
> > you are setting the list of items to itself, and this means there is
> no
> > history at all; the unit of work will ignore it.
> >
> > Setting the list to a series of three brand new secondary items
> > produces
> > the error you see because this generates deletion events for the
> > existing objects which fail because the state of the object is
> > transient.
> >
> > The solution is to expire the relationship attribute first so that
> > it is
> > reset for the transient state.
> >
> >
> >
> >
> > On 10/27/2016 03:43 PM, Colton Allen wrote:
> > > I want to create a new row with all of the same data. However,
> > (using
> > > make_transient) the many-to-many "items" relationship doesn't
> > carry over
> > > to the new model. When I manually set the items I recieve a
> > > "StaleDataError". How can I insert the many-to-many relationships
> so
> > > this does not happen?
> > > *
> > > *
> > > *
> > > My code:*
> > >
> > > class Test(Model):
> > > id = Column(Integer, primary_key=True)
> > > items = orm.relationship('ItemModel',
> secondary=test_item_table)
> > >
> > >
> > > model = Test.query.first()
> > > list_of_items = model.items.copy()
> > >
> > > make_transient(model)
> > > model.id <http://model.id> = None
> > > model.items = list_of_items
> > >
> > > session.add(model)
> > > session.commit()
> > >
> > > # sqlalchemy.orm.exc.StaleDataError: DELETE statement on table
> > > 'test_item' expected to delete 1 row(s); Only 0 were matched.
> > >
> > > --
> > > SQLAlchemy -
> > > The Python SQL Toolkit and Object Relational Mapper
> > >
> > > http://www.sqlalchemy.org/
> > >
> > > To post example code, please provide an MCVE: Minimal, Complete,
> and
> > > Verifiable Example. See http://stackoverflow.com/help/mcve
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> > The Python SQL Toolkit and Object Relational Mapper
> >
> > http://www.sqlalchemy.org/
> >
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
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