Hey,
I'm having a trouble with `joinedload`ing relationships in my models, since
I updated SQLAlchemy from 1.1.2 to 1.1.6.
Sometimes, (and when I say sometimes, i mean 1 out of 50 times or something
like that), when spinning up a server of my python app which uses
SQLAlchemy, I will face this error:
AttributeError: 'NoneType' object has no attribute '_annotations'
I did some digging in the code, and it turns out the `memoized_setups` for
this relationship has empty values in the columns.
Lets say I have two models:
> class A(Model):
> id = Column(Integer, primary_key=True)
> b_id = Column(Integer, ForeignKey('b.id'))
> b = relationship(B)
>
class B(Model):
> id = Column(Integer, primary_key=True)
> foo = Column(String)
>
>
When I face the error, and dig up in the code, I find:
In sqlalchemy/orm/strategies.py in create_row_processor:
our_path = PropRegistry((<Mapper at 0x7f4fe2ae9048; A>,
> <RelationshipProperty at 0x7f4fe2ae1c48; b>))
which calls _instance_processor in sqlalchemy/orm/loading.py: (with
`context=context` and `path=our_path[mapper]`)
quick_populators = path.get(
> context.attributes, "memoized_setups", _none_set)
with leads to: quick_populators =
{
> <ColumnProperty at 0x7f3fe2d01710; id>: Column('id', BIGINT(),
> table=<%(137911348719792 b)s>, primary_key=True, nullable=False),
> <ColumnProperty
> at 0x7f3fe2d01808; foo>: None, }
It's then when trying to get quick_populator[column_object] (which is None)
that I get the error above.
It looks like the context which is passed to `_instance_processor` had bad
memoized data. I have absolutely no clue about what's happening, nor about
a reliable way to reproduce the issue; as said, it happens (randomly?) once
in a while when spinning up a server.
Has it ever happened to you? Do you have a solution for that? Is there more
data you need to evaluate the bug?
NB: everytime this happens (which is not often), I just have to restart the
server and it works. Guess it is just bad data memoized at setup time.
Thanks for reading,
Martin
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http://www.sqlalchemy.org/
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