SQLAlchemy删除级联完整性错误

Question

我想delete一个order从我的数据库,同时删除所有ordereditems,涉及到它.

with contextlib.closing(DBSession()) as session:
    try:
        returnedOrder = session.query(ORDER).filter_by(ORDERSID=orderID).first()
        session.delete(returnedOrder)
        session.commit()
    except exc.SQLAlchemyError, error:
        session.rollback()
        raise_database_error(error)
    else:
        return '1'

这是相关的classes(一些项目已被删除):

class ORDER(Base):
    __tablename__ = 'ORDERS'

    ORDERSID = Column(Integer, primary_key=True)
    ORDERSCOST = Column(Numeric(19, 4), nullable=False)

    ORDEREDITEM = relationship("ORDEREDITEM")  


class ORDEREDITEM(Base):
    __tablename__ = 'ORDEREDITEMS'
    __table_args__ = (
        Index('AK_ORDERSID_ITEMID', 'ORDERSID', 'ITEMSID', unique=True),
    )

    ORDEREDITEMSID = Column(Integer, primary_key=True)
    ITEMSID = Column(ForeignKey(u'ITEMS.ITEMSID'), nullable=False, index=True)
    ORDERSID = Column(ForeignKey(u'ORDERS.ORDERSID', ondelete=u'CASCADE'), nullable=False)
    ORDEREDITEMSQUANTITY = Column(Integer, nullable=False)

    ORDER = relationship(u'ORDER')

该SQL文件中:

create table ORDERS
(
 ORDERSID             int not null auto_increment,     
 ORDERSCOST           decimal(19,4) not null,
 primary key (ORDERSID)
);

create table ORDEREDITEMS
(
 ORDEREDITEMSID       int not null auto_increment,
 ORDERSID             int not null,
 ITEMSID              int not null,
 ORDEREDITEMSQUANTITY int not null,
 primary key (ORDEREDITEMSID),
 unique key AK_ORDERSID_ITEMID (ORDERSID, ITEMSID)
);

alter table ORDEREDITEMS add constraint FK_ORDER_ORDEREDITEM foreign key (ORDERSID)
  references ORDERS (ORDERSID) on delete CASCADE on update restrict;

当我运行它时,我收到错误:

 (IntegrityError) (1452, 'Cannot add or update a child row: a foreign key constraint fails (`my_database`.`ordereditems`,

 CONSTRAINT `FK_ORDER_ORDEREDITEM` FOREIGN KEY (`ORDERSID`) REFERENCES `ORDERS` (`ORDERSID`) ON DELETE CASCADE)') 

'UPDATE `ORDEREDITEMS` SET `ORDERSID`=%s WHERE `ORDEREDITEMS`.`ORDEREDITEMSID` = %s' (None, 3L)

当我直接在phpMyAdmin上执行相同的操作时,它按预期工作.

Answer 1

一个完整的工作示例通常是最有帮助的,但我能够填充示例中缺少的部分,并重现您确切的问题 - 在删除后尝试提交时尝试的UPDATE语句.(这里完全可以使用代码,所有纯python,没有SQL语句.)

这个问题在很多时候都被提出过,我在这个问题中找到了答案.

修复只是为了改变ORDEREDITEM关系

ORDEREDITEM = relationship("ORDEREDITEM")

至

ORDEREDITEM = relationship("ORDEREDITEM", cascade="all,delete")

请在此处查看sqlalchemy文档.