python - SQLAlchemy 查询和_/或_问题

Question

我有一个正在尝试构建的查询。该查询似乎分部分工作，查询的两个单独部分都返回正确数量的元素。但是，组合查询返回一个空结果集，这是不正确的。

注意:我知道查询 1 和查询 2 不需要 and_，但我想确保 and_ 按预期工作。

查询 1:

• SQLAlchemy 查询

  session.query(Lobby).filter(
      and_(
          Lobby.id == spectator_table.c.lobby_id,
          spectator_table.c.player_id == player.steamid
      )
  ).all()
  

• 生成的 SQL

  SELECT lobby.id AS lobby_id, lobby.name AS lobby_name, lobby.owner_id AS lobby_owner_id
  FROM lobby, spectator
  WHERE lobby.id = spectator.lobby_id AND spectator.player_id = ?
  

查询 2:

• SQLAlchemy 查询

  session.query(Lobby).filter(
      and_(
          Lobby.id == Team.lobby_id,
          LobbyPlayer.team_id == Team.id,
          LobbyPlayer.player_id == player.steamid
      )
  ).all()
  

• 生成的 SQL

  SELECT lobby.id AS lobby_id, lobby.name AS lobby_name, lobby.owner_id AS lobby_owner_id
  FROM lobby, team, lobby_player
  WHERE lobby.id = team.lobby_id AND lobby_player.team_id = team.id AND lobby_player.player_id = ?
  

组合查询:

• SQLAlchemy 查询

  session.query(Lobby).filter(
      or_(
          and_(
              Lobby.id == Team.lobby_id,
              LobbyPlayer.team_id == Team.id,
              LobbyPlayer.player_id == player.steamid
          ), and_(
              Lobby.id == spectator_table.c.lobby_id,
              spectator_table.c.player_id == player.steamid
          )
      )
  ).all()
  

• 生成的 SQL

  SELECT lobby.id AS lobby_id, lobby.name AS lobby_name, lobby.owner_id AS lobby_owner_id
  FROM lobby, team, lobby_player, spectator
  WHERE lobby.id = team.lobby_id AND lobby_player.team_id = team.id AND lobby_player.player_id = ? OR lobby.id = spectator.lobby_id AND spectator.player_id = ?
  

---

模型

spectator_table = Table('spectator', Base.metadata,
    Column('lobby_id', Integer, ForeignKey('lobby.id'), primary_key=True),
    Column('player_id', Integer, ForeignKey('player.steamid'),
        primary_key=True
    ),
)

class Lobby(Base):
    __tablename__ = 'lobby'
    id = Column(Integer, primary_key=True)
    name = Column(String, nullable=False)
    owner_id = Column(Integer, ForeignKey('player.steamid'), nullable=False,
        unique=True
    )
    teams = relationship("Team", backref="lobby",
        cascade='save-update,merge,delete'
    )
    spectators = relationship("Player", secondary=spectator_table)

class Team(Base):
    __tablename__ = 'team'
    id = Column(Integer, primary_key=True)
    name = Column(String, nullable=False)
    lobby_id = Column(Integer, ForeignKey('lobby.id'), nullable=False)
    players = relationship("LobbyPlayer", backref="team",
        cascade='save-update,merge,delete,delete-orphan'
    )

class LobbyPlayer(Base):
    __tablename__ = 'lobby_player'
    team_id = Column(Integer, ForeignKey('team.id'), primary_key=True)
    player_id = Column(Integer, ForeignKey('player.steamid'), primary_key=True)
    player = relationship("Player", uselist=False)
    cls = Column(Integer)

class Player(Base):
    __tablename__ = 'player'
    steamid = Column(Integer, primary_key=True)

---

感谢您的帮助!

Answer 1

我在 SA 0.7.9 上看到了同样的问题

似乎令人高兴的是括号没有按照您希望的方式正确应用。我使用了 self_group() 来完成这项工作，但问题是你不应该使用它。这是文档 self_group .我认为应该有比我的更好的答案，但是，这应该让你继续。

query = session.query(Lobby).filter(
    ((Lobby.id == Team.lobby_id) &
    (LobbyPlayer.team_id == Team.id) &
    (LobbyPlayer.player_id == player.steamid)).self_group() |
    ((Lobby.id == spectator_table.c.lobby_id) &
    (spectator_table.c.player_id == player.steamid)).self_group()).all()

生成的sql如下，我相信这就是你所追求的。

SELECT lobby.id AS lobby_id, lobby.name AS lobby_name, lobby.owner_id AS lobby_owner_id 
FROM lobby, team, lobby_player, spectator 
WHERE (lobby.id = team.lobby_id AND lobby_player.team_id = team.id AND lobby_player.player_id = ?) OR (lobby.id = spectator.lobby_id AND spectator.player_id = ?)