python - SQLAlchemy 如何从多对多关系的关联表中获取列值

Question

我有播放列表和轨道类，并将外键分配给播放列表轨道。当我想获取播放列表轨道时一切正常，我使用 playlist.tracks。但现在我还需要获取播放列表轨道的“id”。我如何从关联表中获取“id”或任何额外的列？

playlistsTracks = db.Table('tbl_test_playlisttracks',
                    db.Column('id', db.Integer, primary_key=True),
                    db.Column('playlist_id', db.Integer, db.ForeignKey('tbl_test_playlists.id', ondelete='CASCADE')),
                    db.Column('track_id', db.Integer, db.ForeignKey('tbl_tracks.id'))
                    )



class Track(db.Model):
__tablename__ = 'tbl_tracks'

id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(255))
audio_url = db.Column(db.Text)
movie_id = db.Column(db.Integer)
entry = db.relationship('Playlist', secondary=playlistsTracks, backref=db.backref('tracks', lazy='dynamic'))



class Playlist(db.Model):
__tablename__ = 'tbl_test_playlists'

id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(255))
user_id = db.Column(db.String(255))
current_rev = db.Column(db.Integer, default=0)

Answer 1

db.session.query(playlistsTracks).join(Track).all()

或

db.session.query(playlistsTracks.c.id).join(Track).all()

其他实体播放列表也一样