How to config Many-to-many with condition, in Sqlalchemy

Question

I\'m use sqlalchemy 0.6.4.

I have 2 classes: Question and Tag, they are many-to-many.

class Question(Base):
    __tablename__ = \"questions\"

    id         


        

Answer 1

You can impose extra conditions on the join by replacing SQLAlchemy's default condition via the secondaryjoin parameter to relationship. Since you're replacing the default (not just adding to it), you'll need to manually re-specify the original condition along with the new one:

from sqlalchemy import sql

# ...

class Tag(Base):
    __tablename__ = "tags"

    id = Column(BigInteger, primary_key=True)

    questions = relationship('Question',
        secondary=r_questions_tags,
        secondaryjoin=sql.and_(
            r_questions_tags.c.question_id == Question.id,
            Question.deleted == False))

    deleted_questions = relationship('Question',
        secondary=r_questions_tags,
        secondaryjoin=sql.and_(
            r_questions_tags.c.question_id == Question.id,
            Question.deleted == True))