ruby-on-rails - 具有满足特定条件的关联记录的记录的范围？

Question

我有一个 Customer 模型，其中每个客户都有很多工作:

class Customer < ActiveRecord::Base
  has_many :jobs
end

class Job < ActiveRecord::Base
  belongs_to :customer

  def self.unbilled
    finished.uninvoiced # these are other scopes on Job
  end
end

如何在 Customer 上定义一个范围，它将返回所有具有未开票工作的客户的列表？

Answer 1

您可以 merge范围:

class Customer < ActiveRecord::Base
  has_many :jobs

  scope :freeloaders, joins(:jobs).merge(Job.unbilled)
end