Hello,
My question is linked to a previous question asked here
:https://groups.google.com/forum/#!topic/sqlalchemy/XUHmfrMRhdc.
The context : Horizontal Sharding with dynamic shard (depending of the
execution context).
All works fine for loading (with the solution given in the other thread)
but it fails for deletion.
Example :
class Parent(Base):
__tablename__ = 'parent'
id = Column(Integer, primary_key=True)
children = relationship("Child", lazy=True)
class Child(Base):
__tablename__ = 'child'
id = Column(Integer, primary_key=True)
parent_id = Column(Integer, ForeignKey('parent.id'))
If I want to delete a parent instance (its shard id is know), the orm tries
to load the children items before (cascade delete).
To do it, a query is created from the Child mapper
(LazyLoader._emit_lazyload function).
On query execution, my shard session calls my "query_chooser" function. The
problem is that I need to got the shard_id from the parent object instance
and I didn't find it in the query object...
I can solve my problem by overwritting the method "_emit_lazyload" in
LazyLoader class but I don't know if it is possible and how to do it...
Thanks,
Julien
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