Rails使用includes和嵌套的belongs_to来加载

Question

说我有三个型号:

class Foo < ActiveRecord::Base
  has_many :things
end

class Thing < ActiveRecord::Base
  belongs_to :foo
  belongs_to :other_thing
end

class OtherThing
  has_many :things
end

我怎样才能从以下方面出发Foo并急切地加载OtherThing:

Foo.includes([:things => [:other_things]})

我搜索过但找不到任何东西.

谢谢

Answer 1

包含和连接使用与您定义的关系相同的语法:

Foo.includes(:things => :other_thing)

会工作因为:

Foo has_many :things
                   ^
Thing belongs_to :other_thing
                            ^^

但请记住,在where子句中,始终使用复数版本:

Foo.includes(:things => :other_thing).where(other_things: { name: 'Bobby' })
                                   ^^                 ^^