FastAPI Postgres 級聯刪除

Question

我有 2 張桌子，“書”和“書簽”。
如何在模型上設置級聯，以便當他們刪除“Book”時，他們也會刪除基於“Book”的“Bookmark”。

這是模型：

class Book(Base):
    __tablename__ ="book"

    id = Column(Integer, primary_key=True, index=True, autoincrement=True)
    title = Column(String, nullable=False)
    description = Column(String, nullable=True)

    # relation
    r_bookmark = relationship("BookMark", back_populates="r_book")


class BookMark(Base):
    __tablename__ ="bookmark"

    id = Column(Integer, primary_key=True, index=True, autoincrement=True)
    title = Column(String, nullable=False)
    description = Column(String, nullable=True)
    book_id = Column(Integer, ForeignKey("book.id", ondelete='CASCADE'), nullable=False)

    # relation
    r_book = relationship("Book", back_populates="r_bookmark", cascade="all,delete")

請幫忙，謝謝。

Answer 1

感謝 MatsLindh，這是正確的答案：

class Book(Base):
    __tablename__ ="book"

    id = Column(Integer, primary_key=True, index=True, autoincrement=True)
    title = Column(String, nullable=False)
    description = Column(String, nullable=True)

    # relation
    r_bookmark = relationship("BookMark", back_populates="r_book", cascade="all,delete")


class BookMark(Base):
    __tablename__ ="bookmark"

    id = Column(Integer, primary_key=True, index=True, autoincrement=True)
    title = Column(String, nullable=False)
    description = Column(String, nullable=True)
    book_id = Column(Integer, ForeignKey("book.id"), nullable=False)

    # relation
    r_book = relationship("Book", back_populates="r_bookmark")

我已將cascade添加到父表上的relation ，而不是子表。