the error is raised because there is more than one column on your subclass
table that is a foreign key to the superclass table. SQLAlchemy refuses to
guess which of these columns it should use to create the join condition between
superclass and subclass table.
On Tue, Sep 8, 2020, at 4:50 PM, maqui...@gmail.com wrote:
> I'm having the same problem,
> I have a base class called TrackedEntity that has child classes like Request
> and others that inherit from it
>
> on Request I wanted to put a reference to the id of the TrackedEntity that
> created the Request
> class Request(TrackedEntity, TrackedEntityContainer, VisibleIdMixin):
> parent_tracked_entity_id = Column(UUID, ForeignKey("tracked_entity.id"))
>
> and I get the same error as above. Adding that inherit condition makes the
> runtime error stop, but it doesn't make sense to me. Why can't I just have a
> foreign key to that table? It's a simple many to one
>
>
> @Richard: you can use @declared_attr.cascading to cascade the mapper_args to
> your child classes.
> On Friday, August 28, 2020 at 2:56:02 PM UTC-4 Richard Damon wrote:
>> Thank you, so that go into each subclass that would have the problem.
>>
>> 8/28/20 2:37 PM, Mike Bayer wrote:
>> > the argument you're looking for is inherit_condition:
>> >
>> > https://docs.sqlalchemy.org/en/13/orm/mapping_api.html#sqlalchemy.orm.mapper.params.inherit_condition
>> >
>> >
>> >
>> > class Foo(...):
>> > __mapper_args__ = {
>> > "inherit_condition": node_id == Node.node_id
>> > }
>> >
>>
>> --
>> Richard Damon
>>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
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SQLAlchemy -
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http://www.sqlalchemy.org/
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