Django查询：从不直接相关的模型中获取值

Question

我想从 Django 中不直接相关的模型中获取价值。 我有以下型号：

class Platform(models.Model):
    platform = models.CharField()


class Game(models.Model):
    game = models.CharField()
    genre = models.CharField()


class Link(models.Model):
    game = models.ForeignKey(Game)
    platform = models.ForeignKey(Platform)

如何获取游戏对象的 QuerySet，其中游戏标题（Game.game 字段）将被替换为以下模式：游戏（平台）（例如“战地（PS3）”）而无需额外点击数据库？

在 SQL 中它看起来像这样：

SELECT
  g.id,
  g.game || ' (' || p.platform || ')' AS game
FROM game g INNER JOIN link l ON g.id = l.game_id
  LEFT JOIN platform p ON l.platform_id = p.id;

Answer 1

您可以使用 link_set 来获取游戏的反向查找，这里是 django documentation

class Platform(models.Model):
    platform = models.CharField()


class Game(models.Model):
    game = models.CharField()
    genre = models.CharField()

    def save(self, *args, **kwargs):
        self.title = "{0} ({1})".format(self.title, self.link__platform)
        super(Game, self).save(*args, **kwargs)


class Link(models.Model):
    class Meta:
        unique_together = ('game', 'platform')
    game = models.ForeignKey(Game)
    platform = models.ForeignKey(Platform)