python - Sqlalchemy 覆盖关联表中的字段

Question

我有两个实体，Player 和 Game，它们之间的关系是多对多的。 Player 以及Player 和Game 之间的连接(PlayerGame)都有得分

class Player(db.Model):
 id = db.Column(db.Integer, primary_key=True, autoincrement=True)
 score = db.Column(db.Float)
 name = db.Column(db.String(45), nullable=False)

class Game(db.Model):
  id = db.Column(db.Integer, primary_key=True, autoincrement=True)
  name = db.Column(db.String(45))

class PlayerGame(db.Model):
  player_id = db.Column(db.Integer, db.ForeignKey('players.id'), primary_key=True)
  game_id = db.Column(db.Integer, db.ForeignKey('games.id'), primary_key=True)
  score = db.Column(db.Float)

  player = db.relationship("Player", backref="games")
  game = db.relationship("Game", backref="players")

我想使用给定游戏 ID 的 sqlalchemy 编写查询，返回所有相关玩家，但他们的分数将被游戏分数覆盖

到目前为止，我的查询看起来像这样

Player.query.join(PlayerGame, and_(
    PlayerGame.player_id == Player.id,
    PlayerGame.game_id == game_id))\
.options(contains_eager(Player.games))

我正在考虑更改 Player.score 和 PlayerGame.score 标签名称，或者排除 Player.score 但以上都不是真的似乎有效

可以在 python 代码查询之后执行此操作，但理想情况下，我希望它成为查询的一部分

Answer 1

我稍微调整了你的模型，然后在下面使用了一个不返回“Player”对象的查询，因为结果是来自玩家的属性和来自 PlayerGame 的属性:

class Player(db.Model):
  id = db.Column(db.Integer, primary_key=True, autoincrement=True)
  score = db.Column(db.Float)
  name = db.Column(db.String(45), nullable=False)
  playergames = db.relationship('PlayerGame', backref='player', lazy=True, 
     cascade="delete")

class Game(db.Model):
  id = db.Column(db.Integer, primary_key=True, autoincrement=True)
  name = db.Column(db.String(45))
  playergames = db.relationship('PlayerGame', backref='game', lazy=True, 
  cascade="delete")

class PlayerGame(db.Model):
  player_id = db.Column(db.Integer, db.ForeignKey('player.id'), primary_key=True)
  game_id = db.Column(db.Integer, db.ForeignKey('game.id'), primary_key=True)
  score = db.Column(db.Float)

p = Player(name = "Hoffmann", score = 7.5)
p1 = Player(name = "Fink", score = 4.5)
db.session.add(p)
db.session.add(p1)

g = Game(name = "VfB")
g1 = Game(name = "HSV")

db.session.add(g)
db.session.add(g1)

pg = PlayerGame(player = p, game = g, score = 1.5)
pg1 = PlayerGame(player = p1, game = g, score = 3.5)
db.session.add(pg)
db.session.add(pg1)
db.session.commit()    

playergamescores = db.session.query(Player.name, 
    PlayerGame.score).join(Player).filter(PlayerGame.game_id == g.id).all()   
print(playergamescores)

然后输出是 [('Hoffmann', 1.5), ('Fink', 3.5)]