有條件地通過關聯創建has_many：

Question

我有以下課程：

class Physician < ActiveRecord::Base
  has_many :appointments
  has_many :patients, through: :appointments
end

class Appointment < ActiveRecord::Base
  belongs_to :physician
  belongs_to :patient
end

class Patient < ActiveRecord::Base
  has_many :appointments
  has_many :physicians, through: :appointments
end

我只希望醫師能夠創建一個約會，而不能創建一個病人。 請讓我知道如何在模型級別上具有此限制。

謝謝！

Answer 1

您無需使用關聯來檢索患者約會對象。 只需為他們創建一個getter方法：

class Patient < ActiveRecord::Base
  def appointments
    Appointment.where(patient_id: self.id)
  end
end