I'm trynig to use association_proxy to map a collection of items through an
intermediary table
I'm running into a problem where I can't figure out a way to eagerload the
collection through the extension.
if i do:
query.options(joinedload('to_items', 'to_items.item'))
I can loop through to_items and item fine.
When I loop '.items', I hit the DB.
I tried eagerloading the 'items' relation, and that didn't work either.
I must be using the association_proxy wrong. Does anything here jump out
to others?
class Collection()
__tablename__ = 'collection'
id = sa.Column(sa.Integer, primary_key=True)
name = sa.Column(sa.Unicode(32), nullable=False)
to_items = sa.orm.relationship("item_2_collection",
primaryjoin="collection.id==Item2Collection.collection_id",
back_populates='collection',
)
items = association_proxy('to_items', 'item')
class Item():
__tablename__ = 'item'
id = sa.Column(sa.Integer, primary_key=True)
name = sa.Column(sa.Unicode(32), nullable=False)
class Item2Collection()
__tablename__ = 'item_2_collection'
__primarykey__ = ['item_id', 'collection_id']
item_id = sa.Column(sa.Integer, sa.ForeignKey("item.id"),
nullable=False, primary_key=True)
collection_id = sa.Column(sa.Integer,
sa.ForeignKey("collection.id"), nullable=False, primary_key=True)
# relations
item = sa.orm.relationship("Item",
primaryjoin="Item2Collection.item_id==Item.id",
uselist=False,
)
collection = sa.orm.relationship("Collection",
primaryjoin="Item2Collection.collection_id==Collection.id",
back_populates='to_items',
uselist=False,
)
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