session.query(Parent).options(defaultload("children").load_only("cheap_column"))
or really if you want to cut out "expensive_column"
session.query(Parent).options(defaultload("children").defer("expensive_column"))
http://docs.sqlalchemy.org/en/rel_0_9/orm/mapper_config.html#deferred
On May 10, 2014, at 6:39 PM, Seth <[email protected]> wrote:
> Is there any way to get SQLAlchemy to only load specific columns through a
> relationship()?
>
> For example, with this scenario:
>
> class Parent(Base):
> __tablename__ = 'parent'
> id = Column(Integer, primary_key=True)
> children = relationship("Child", lazy='joined')
>
> class Child(Base):
> __tablename__ = 'child'
> id = Column(Integer, primary_key=True)
> parent_id = Column(Integer, ForeignKey('parent.id'))
> cheap_column = Column(Unicode(10))
> expensive_column = Column(LargeBinary)
>
> I'd like Child to get lazily joined when Parent is loaded, but only with
> Child's "cheap_column" and not it's "expensive_column".
>
> Thanks,
> Seth
>
>
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