Python 为什么我会得到；InvalidRequestError"；？

根据ORM教程，我尝试使用联接在表和查询之间实现一些外键：

from sqlalchemy import (Column, ForeignKey, Integer, create_engine)
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, relationship

Base = declarative_base()

class DataAccessLayer():

    def __init__(self):
        conn_string = "mysql+mysqlconnector://root:root@localhost/"
        self.engine = create_engine(conn_string)

    def create_session(self):
        Base.metadata.create_all(self.engine)
        Session = sessionmaker()
        Session.configure(bind=self.engine)
        self.session = Session()

class Bet(Base):

    __tablename__ = "bet"
    __table_args__ = ({"schema": "belgarath", "extend_existing": True})

    id_ = Column(Integer, primary_key=True)
    match_id = Column(Integer, ForeignKey("belgarath.match_.id_"))

    match_ = relationship("Match", back_populates="belgarath.bet")

class Match(Base):
    __tablename__ = "match_"
    __table_args__ = ({"schema": "belgarath", "extend_existing": True})

    id_ = Column(Integer, primary_key=True)
    tournament_id = Column(Integer)= Column(Integer)

dal = DataAccessLayer()
dal.create_session()

bets = dal.session.query(Bet)
bets.join(Match)
for bet in bets:
    print(bet.id_, bet.tournament_id = Column(Integer))

但是，我在

bets=dal.session.query（Bet）

行中遇到以下错误：

Exception has occurred: InvalidRequestError
Mapper 'mapped class Match->match_' has no property 'belgarath.bet'

---

我哪里做错了？在

Match

中是否需要某种对等关系？

您是否已经尝试将

back\u populates

更改为

back\u ref

。您好。我得到了以下错误：

TypeError:relationship（）得到了一个意外的关键字参数“back\u ref”

对不起，我搞错了<代码>反向参考非

反向参考