here we are, please complete and return, thanks
from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
atob = Table(
'atob', Base.metadata,
Column('aid', ForeignKey('a.id'), primary_key=True),
Column('bid', ForeignKey('b.id'), primary_key=True)
)
class A(Base):
__tablename__ = 'a'
id = Column(Integer, primary_key=True)
bs = relationship("B", secondary=atob)
class B(Base):
__tablename__ = 'b'
id = Column(Integer, primary_key=True)
e = create_engine("sqlite://", echo=True)
Base.metadata.create_all(e)
session = Session(e)
a1 = A(bs=[B(), B(), B()])
session.add(a1)
session.commit()
# please illustrate failure here
On 10/28/2016 09:13 AM, Colton Allen wrote:
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> <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,
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> > Verifiable Example. See http://stackoverflow.com/help/mcve
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