On Fri, Feb 14, 2020 at 5:35 PM Mark Aquino <maquino1...@gmail.com> wrote:
>
> I have a polymorphic class structure like this, with a lot of classes
> extending the parent class.
> In reality I'm using a Mixin that declares the visible_id column and it's
> defined with @declared_attr.cascading, but for simplicity:
>
>
>
> class A(Base):
> __tablename__ = 'a'
> id = Column(Integer, primary_key=True)
> visible_id = Column(Integer)
>
> class B(A):
> __tablename__ = 'b'
> id = Column(Integer, ForeignKey("A.id"), primary_key=True)
> visible_id = Column(Integer)
>
>
> What I need for my application is to query A.visible_id and return the CHILD
> values for B.visible_id (and all the others).
>
> The inheritance works fine, i.e. if i query all As in the database, my
> response is a list of [B] objects, but unless I directly query B the
> visible_id from A takes precedence and I cannot query A.visible_id if I
> remove it from A.
>
> Can anyone tell me how to configure this?
>
Out of interest, what is the point of having a visible_id column in
the B table? I'm having difficulty imagining what it would mean to
have an instance of B (which due to inheritance is also an instance of
A) which has different values in A.visible_id and B.visible_id.
Simon
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