Question

我有两张桌子，我正在尝试建立一对多的关系。应该有一个Player个Sessions。

import sqlalchemy as sql
from sqlalchemy.orm import relationship
from sqlalchemy.ext.declarative import declarative_base

Base = declarative_base()

class Session(Base):
    __tablename__ = 'session'

    id = sql.Column('session_id', sql.INTEGER, primary_key=True)
    player_id = sql.Column(sql.INTEGER, sql.ForeignKey('player.player_id'))

class Player(Base):
    __tablename__ = 'player'

    id = sql.Column('player_id', sql.INTEGER, primary_key=True)
    sessions = relationship('Session', backref='player')

但是，我在创建数据库时遇到的错误是

sqlalchemy.exc.InvalidRequestError: One or more mappers failed to initialize - 
can't proceed with initialization of other mappers. Triggering mapper: 
'Mapper|Player|player'. Original exception was: When initializing mapper 
Mapper|Player|player, expression 'Session' failed to locate a name ("name 
'Session' is not defined"). If this is a class name, consider adding this 
relationship() to the <class 'analysis_db_tables.Player'> class after both 
dependent classes have been defined.

我已尝试更改Player和Session的顺序，将relationship行删除为Player以外的

Player.sessions = relationship('Session', backref='player')

我也尝试在两个类中使用back_populates和relationship语句。我在这里做错了什么？

这个问题在构建我的数据库代码时似乎随机出现，我已经将表格配对到这两个，同时仍然重新创建问题。我正在使用SQLAlchemy和postgres。感谢。

Answer 1

尝试：

sessions = sql.relationship('Session', backref='player')

而不是：

sessions = relationship('Session', backref='player')

SQLAlchemy关系问题 - 映射器无法找到名称

1 个答案: