Rails避免N + 1查詢

Question

給定以下模型關系。

group has_many :members
member has_many :missions
mission has_one :game_set_mission
mission has_one :game_set, :through => :game_set_mission

這是我的工作

給定組是一個組對象

# Add a new relationship in member.rb
has_many :game_sets, :through => :missions

# Get all game_set id
group.members.map{ |gc| gc.game_sets.pluck(:id) }

但是似乎發生了N+1 query 。

如何改善我的代碼？

Answer 1

希望以下一項對您有所幫助。

GameSet.includes(member: :group)
       .where('groups.id = ?', group.id)
       .pluck('game_sets.id')