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 = 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.

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