使用ActiveRecord的多个加入条件

如何解决使用ActiveRecord的多个加入条件

我有以下型号

class Electrician < ApplicationRecord
  belongs_to :user
end

class Proposal < ApplicationRecord
   belongs_to :visit
   belongs_to :electrician
end

class VisitAvailability < ApplicationRecord
  belongs_to :visit
  belongs_to :requester,foreign_key: :requested_by_id,class_name: 'User'

  scope :enabled,-> { where(state: 0) }

end

我正在尝试为Proposal添加一个范围到with_electrician_availability。它应该返回Proposals表中所有可用的visit_availabilities。在原始sql中，我想我想要这样的东西

SELECT * FROM proposals
INNER JOIN electricians ON proposals.electrician_id = electricians.id
INNER JOIN users ON users.id = electricians.user_id
INNER JOIN visit_availabilities ON (proposals.visit_id = visit_availabilities.visit_id AND proposals.requester_id = users.id)
WHERE visit_availabilities.state = 0

但是我似乎无法弄清楚如何使用ActiveRecord做到这一点。感觉我应该能够向has_many :booking_availabilities添加一个Proposal关联，但是我不确定如何使用多个联接列来实现这一点