SQLAlchemy:两侧多对多动态加载 [英] SQLAlchemy: Many-to-Many dynamic loading on both sides

问题描述

假设我有以下内容:

association_table = Table('things_stuffs', Base.metadata,
    autoload=True,
    extend_existing=True)

class Thing(Base):
    __tablename__ = 'things'
    __table_args__ = {'autoload': True}

class Stuff(Base):
    __tablename__ = 'stuffs'
    __table_args__ = (
        {'autoload': True}
        )
    things = relationship(Thing,
                secondary=association_table,
                backref=backref("stuffs", uselist=False, lazy='dynamic'))

现在，如果我想从Stuff实例中获取所有信息，我可以做:

Now, if I want to get all the things from a Stuff instance I can do:

a_stuff_instance.things.filter().all()

并由于 lazy ="dynamic" 部分对其进行查询.但是，另一端却无法正常工作.如果我想做

And query it because of the lazy="dynamic" part. But the other side doesn't work. If I want to do

a_thing_instance.stuffs.filter().all()

我得到 AttributeError:'InstrumentedList'对象没有属性'filter'.我该怎么办?

推荐答案

也只需在另一侧添加 dynamic :

things = relationship(Thing,
            secondary=association_table,
            lazy='dynamic', # *** @note: new parameter ***
            backref=backref("stuffs", uselist=False, lazy='dynamic'))

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