I've changed the assertions to all expect "3" items since assertions
should illustrate what's expected to happen (this again communicates to
me what the problem is).
Applying expire() to all three (plus reassignment in the first case)
allows them all to work. If you don't expire the relationship,
make_transient has nothing to do with them, they remain as "unchanged"
from a history perspective.
bs = a1.bs
session.expire(a1, ['bs'])
make_transient(a1)
a1.id = None
a1.bs = bs
session.add(a1)
session.commit()
assert len(a1.bs) == 3
model = session.query(A).first()
bs = model.bs.copy()
assert len(bs) == 3
session.expire(model, ['bs'])
make_transient(model)
model.id = None
model.bs = bs
session.add(model)
session.commit()
assert len(model.bs) == 3
model = session.query(A).first()
bs = session.query(B).all()
assert len(bs) == 3
session.expire(model, ['bs'])
make_transient(model)
model.id = None
model.bs = bs
session.add(model)
session.commit()
assert len(model.bs) == 3
On 10/28/2016 10:43 AM, Colton Allen wrote:
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
#
# Example 1. M2M is empty after being made transient.
#
assert len(a1.bs) == 3
make_transient(a1)
a1.id = None
session.add(a1)
session.commit()
assert len(a1.bs) == 0
#
# Example 2. M2M remains empty ever after being assigned relationships.
#
model = session.query(A).first()
bs = model.bs.copy()
assert len(bs) == 3
make_transient(model)
model.id = None
model.bs = bs
session.add(model)
session.commit()
assert len(model.bs) == 0
#
# Example 3. M2M is populated from fresh query.
#
model = session.query(A).first()
bs = session.query(B).all()
assert len(bs) == 3
make_transient(model)
model.id = None
model.bs = bs
session.add(model)
session.commit()
assert len(model.bs) == 3
On Friday, October 28, 2016 at 9:47:44 AM UTC-4, Mike Bayer wrote:
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 <http://a.id>'), primary_key=True),
Column('bid', ForeignKey('b.id <http://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>
<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
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> >
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>
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>
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http://www.sqlalchemy.org/
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