make sure you are always using order_by if you're doing any kind if
limit/offset (including if you call the first() accessor), see the notes
at
http://docs.sqlalchemy.org/en/rel_1_0/orm/loading_relationships.html#the-importance-of-ordering
and
http://docs.sqlalchemy.org/en/rel_1_0/faq/ormconfiguration.html#faq-subqueryload-limit-sort.
On 05/12/2016 08:30 PM, Marco wrote:
Greetings,
[SQLAlchemy 1.0.12]
We have observed situations in which the first in a list of objects
returned by a query with options(subqueryload(Class.relationship)) or
with lazy=subquery will have a missing relationship.
This is some pseudocode
[...]
class Parent(Base):
id = Column(Integer, primary_key=True)
class Child(Base):
id = Column(Integer, primary_key=True)
parent_id = Column(Integer, ForeignKey(Parent.id))
Child.parent = relationship(Parent, lazy='subquery')
[...]
children = session.query(Child).all()
children[0].parent_id not None
children[0].parent None!!!
children[1].parent_id not None
children[1].parent not None
If I change the strategy to eager or lazy='select' things are fine.
I have not successfully isolated this issue into a toy model, but I'd be
happy to dig deeper if pointed to the relevant code. I can reproduce
this in our code easily.
Thanks!
Marco
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