使用关联的模型范围

Question

如果我有一个名为User 的模型has_many :games 和游戏has_many :events- 我如何获取所有没有任何游戏或有任何游戏暂停事件的用户。

这是我尝试过的：

例子：

用户类别：

scope :with_no_games -> {
  joins("LEFT OUTER JOIN games g on g.user_id = users.id").where("games.id IS NULL")
}  

scope :with_suspended_games_or_no_games -> {
  with_no_games.merge(Game.suspended) # <- this doesn't work
}

游戏类：

scope :suspended -> {
  joins("INNER JOIN events e ON event.game_id = games.id AND event.name = 'suspended'")
}

如果我运行User.with_suspended_games_or_no_games，我会得到以下 SQL 语句：

SELECT \"users\".* FROM \"users\" LEFT OUTER JOIN games ON games.user_id = users.id INNER JOIN events ON events.game_id = games.id AND events.name = 'suspended' WHERE (games.user_id IS NULL)"

这不是我想要的。我错过了什么？

Answer 1

我想你正在寻找

scope :with_suspended_games_or_no_games -> {
  with_no_games.joins(:games).merge(Game.suspended)
}

要查看 sql，请尝试从 rails 控制台运行以下命令：

User.with_suspended_games_or_no_games.to_sql

奖金

你也可以这样写你的作用域：

用户

scope :with_no_games -> { joins(:games).where(games: {id: nil}) }
scope :with_suspended_games_or_no_games -> { joins(:games).with_no_games.merge(Game.suspended) }

游戏

scope :suspended -> { joins(:events).where(events: {name: 'suspended'}) }