Thank you for the suggestion but the extension method doesn't fired,
even without raw sql:
mapper(Account, table_accounts, extension=AccountLoader(),
properties=dict(
children = relation(Account, lazy=None,
primaryjoin=table_accounts.c.parent_id==table_accounts.c.account_id,
#cascade="all",
collection_class=attribute_mapped_collection('name'),
backref=backref('parent',
primaryjoin=table_accounts.c.parent_id==table_accounts.c.account_id,
remote_side=table_accounts.c.account_id)
),
chart = relation(Account, lazy=None, uselist=False,
post_update=True,
primaryjoin=table_accounts.c.chart_id==table_accounts.c.account_id,
remote_side=table_accounts.c.account_id,
backref=backref('descendants', lazy=None,
join_depth=1,
primaryjoin=table_accounts.c.chart_id==table_accounts.c.account_id,
viewonly=True)
),
class AccountLoader(MapperExtension):
def append_result(self, mapper, selectcontext, row, instance,
result, **flags):
isnew = flags.get('isnew', False)
if instance.parent_id is None:
result.append(instance)
else:
if isnew or selectcontext.populate_existing:
key =
mapper.identity_key_from_primary_key(instance.parent_id)
parentnode = selectcontext.session.identity_map[key]
parentnode.children.append(instance)
return False
accounts = Session.query(Account).filter(Account.c.chart_id==1).all()
How can I fire the extension callback without eager loading
descendants?
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