使用连接 Rails 的嵌套记录

Question

我有这些模型

class Car < ApplicationRecord
  has_many :car_locations ,:dependent=>:destroy
  has_many :rides,:dependent=>:destroy
end

class CarLocation < ApplicationRecord
  belongs_to :car
end

class Ride < ApplicationRecord
  belongs_to :car
end

boolean 类型的 Ride 模型中有一个 status 属性。

现在我想要那些 CarLocation 的乘车状态为 false 或没有乘车的最低复杂度。

Answer 1

I want those Car Locations whose car rides status is false

CarLocation.joins(car: :rides).where(rides: { status: false })

or don't have any car ride

CarLocation.includes(car: :rides)
           .where(rides: { id: nil })
           .references(:rides)

将两者结合在一起：

CarLocation.includes(car: :rides)
           .where('rides.status = false OR rides.id IS NULL')
           .references(:rides)

使用连接 Rails 的嵌套记录

Nested records using join Rails

ruby

ruby-on-rails

ruby-on-rails-5