Flask-SQLAlchemy에서 secondaryjoin

 

원하는 테이블끼리 직접적인 릴레이션이 없을 때, 한단계 거쳐서 가져와야할 때 사용. 

 

class User(db.Model):
    ....
    
class Question(db.Model):
    ...
    users = db.relationship('User', secondary='answer', backref='answer.uid')

class Answer(db.Model):
    uid = db.Column(db.String(36), db.ForeignKey('user.id', ondelete="CASCADE"), nullable=False)
    qid = db.Column(db.String(36), db.ForeignKey('question.id', ondelete="CASCADE"), nullable=False)
 

 

stackoverflow.com/questions/19598578/how-do-primaryjoin-and-secondaryjoin-work-for-many-to-many-relationship-in-s

How do 'primaryjoin' and 'secondaryjoin' work for many-to-many relationship in SQLAlchemy?

docs.sqlalchemy.org/en/14/orm/join_conditions.html#composite-secondary-joins

Configuring how Relationship Joins — SQLAlchemy 1.4 Documentation