Rails- has_many：通过创建、删除和访问记录

Question

以下代码来自http://guides.rubyonrails.org/association_basics.html#the-has_many-through-association

class CreateAppointments < ActiveRecord::Migration
 def change
  create_table :physicians do |t|
   t.string :name
   t.timestamps null: false
  end

create_table :patients do |t|
  t.string :name
  t.timestamps null: false
end

create_table :appointments do |t|
  t.belongs_to :physician, index: true
  t.belongs_to :patient, index: true
  t.datetime :appointment_date
  t.timestamps null: false
end

结束 结束

在上面的例子中我是怎么做的：

1) 创建/破坏医生和患者之间的关系。我只是使用：

Create: Appointment.create(physician_id, patient_id)
Destroy: (i have no clue hot to do this)

正确的做法是什么？

2) 我如何访问特定患者或医生的预约模型中的所有预约日期？

Answer 1

1/

 Appointment.find_by(physician: @physician, patient: @patient).destroy

2/

 @patient.appointments.pluck(:appointment_date)

Answer 2

您可以根据自己的喜好创建医生或患者的预约：

@patient = Patient.find(params[:id])
@patient.appointments.create(physician: *object*, appointment_date: *datetime object*)  # auto sets the patient to match the @patient.id

#or from the physician
@physician = Physician.last #select the last physician
@physician.appointments.create(patient: *object*, appointment_date: *datetime object*) # auto sets the physician to match the @physician.id

如果你有两个 ID，你也可以这样创建：

Appointment.new(patient: *Patient object*, physician: *Physician object*, appointment_date: *datetime object*)

要销毁记录，只需找到活动记录对象并对其调用destroy即可。在控制台中玩耍，看看它是如何工作的。例如：

Patient.find(id).appointments.last.destroy #destroys the last appointment for a patient with id

或直接查找并删除约会：

# find active record and then call destroy
@appointment = Appointment.find(1) # find appointment with ID: 1
@appointment.destroy

#call destroy directly by chaining commands
Appointment.find(1).destroy #does the exact same thing as above.