I need to change a collection order_by when a parent instance mapped
attribute changes.
Something like this:
parents = Table('parents', metadata,
Column('id', Integer, primary_key=True)
Column('reverse', Boolean, primary_key=True)
)
items = Table('items', metadata,
Column('id', Integer, primary_key=True)
)
....
mapper(parents, Parent,
properties={
'items': relationship(Item,
backref='parent',
collection_class=ItemsList,
order_by=items.c.id
)
}
>>> parent = session.query(Parent).first()
>>> parent.reverse
False
>>> parent.items
[<Item 1>, <Item 2>, <Item 3>]
>>> parent.reverse = True
>>> parent.items
[<Item 3>, <Item 2>, <Item 1>]
I already use a custom collection and I could make custom __iter__
according to first item (if any) `self.parent.reverse` but it seems to
me a bit too tricky.
Any advice?
Thank you for your support
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