使用關聯的模型範圍

Question

如果我有一個模型Userhas_many :games和遊戲has_many :events - 我如何獲得沒有任何遊戲的所有用戶或任何有暫停事件的遊戲。

這是我曾嘗試：

例子：

用戶等級：

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 
} 

遊戲類：

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

如果我跑User.with_suspended_games_or_no_games我得到下面的SQL聲明：

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)"

這不是我正在尋找的。我錯過了什麼？

Answer 1

我認爲你正在尋找

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

查看SQL嘗試運行從鐵軌控制檯以下：

User.with_suspended_games_or_no_games.to_sql 

獎金

你也可以寫你的範圍如：

用戶

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) } 

遊戲

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