外键约束失败，级联不删除相关对象

如何解决外键约束失败，级联不删除相关对象

我已经在外键上定义了 cascade="all,delete-orphan" 并定义了 ondelete="CASCADE"，但是当我删除与预订相关的客户行时，我仍然得到 "sqlalchemy.exc.IntegrityError: (sqlite3.IntegrityError) FOREIGN KEY constraint Failed"。

from sqlalchemy import Column,Integer,String,Table
from sqlalchemy.orm import relationship
from sqlalchemy.sql.schema import ForeignKey
from database import Base
    
    
class Customer(Base):
    __tablename__ = "customers"
  
    id = Column(Integer,primary_key=True,index=True)
    name = Column(String)
    type = Column(String)
    booking = relationship("Booking",back_populates='customer',cascade="all,delete-orphan")
    
class Booking(Base):
    __tablename__ = "bookings"
 
    id = Column(Integer,index=True)
    cid = Column(Integer,ForeignKey("customers.id",ondelete="CASCADE"),nullable=False)
    name = Column(String)
    type = Column(String)
    customer = relationship('Customer',back_populates='booking')

@app.delete('/customer/{id}')
def destory(id,db:Session = Depends(get_db)):
    customer=db.query(models.Customer).filter(models.Customer.id == id)
    if not customer.first():
        raise HTTPException(status_code=404,detail=f'Blog with the id {id} is not available '
        )
    #db.delete(customer.first())
    customer.delete(synchronize_session=False)
    db.commit()
    return 'done'