从SQLalchemy和Flask中的相关列表中查询 [英] Querying from list of related in SQLalchemy and Flask

问题描述

我有User，其中has-one Person.所以User.person是Person.
我正在尝试从Person的列表中获取User的列表.

I have User which has-one Person. So User.person is a Person.
I am trying to get a list of User from a list of Person.

我尝试了以下操作:

>>> people = Person.query.filter().limit(3)
<flask_sqlalchemy.BaseQuery object at 0x111c69bd0>

>>> User.query.filter(User.person.in_(people)).all()
NotImplementedError: in_() not yet supported for relationships.  For a simple many-to-one, use in_() against the set of foreign key values.

获取User列表(其中User.person在该people列表中)的最佳方法是什么?

What is the best way to get a list of Users where User.person is in that list of people?

推荐答案

该错误消息会告诉您，您需要对外键使用in_:

As the error message helpfully tells you, you need to use in_ against the foreign keys instead:

User.query.join(User.person).filter(Person.id.in_(p.id for p in people)).all()

因为无论如何都要查询两者，所以最好先做一个合并的加载，然后再让人们使用Python:

Since you're going to query for both anyway, might be better to do a joined load and then get the people using Python:

people = Person.query.join(Person.user).options(db.contains_eager(Person.user)).limit(3).all()
users = [p.user for p in people]

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