SQLAlchemy 外键约束混淆

Question

I just want to delete a survey record in the Survey table, and the record in SurveyQuestions should be deleted too. I've tried cascade , passive_deletes , and ondelete . I keep getting the foreign key violation error no matter what I try from the documentation. Is it the way my tables are set up?

class Survey(Base):
    __tablename__ = 'survey'
    id = Column(Integer, primary_key=True, autoincrement=True)
    survey_description = Column(String(100))
    survey_start_date = Column(Date)
    survey_end_date = Column(Date)
    survey_is_active = Column(Boolean)
    survey_questions = relationship(Question, secondary='survey_questions',cascade="all, delete",passive_deletes=True)


class SurveyQuestions(Base):
    __tablename__ = 'survey_questions'
    id = Column(Integer, primary_key=True, autoincrement=True)
    survey_id = Column(Integer, ForeignKey('survey.id', ondelete='CASCADE'))
    question_id = Column(Integer, ForeignKey('question.id', ondelete='CASCADE'))

Answer 1

Are there other models that use Survey as a foreign key? Perhaps the foreign key violation happens because you didn't specify ondelete strategy in another model that points to Survey

Answer 2

So I had to drop all the tables using Base.metadata.drop_all(engine) before the foreign key relations would take effect. Since then we have adopted alembic to remedy this issue through the use of migrations.