如何使用关联访问其他表的属性

Question

“大家好”我现在正在使用rails练习一点点，并且遇到关于如何通过关联访问数据的问题。目前我有3张桌子，医生，病人和约会。

 class CreateDoctors < ActiveRecord::Migration 
     def change 
     create_table :doctors do |t| 
      t.string :name 

      t.timestamps null: false 
     end 
     end 
    end 

     class CreatePatients < ActiveRecord::Migration 
     def change 
     create_table :patients do |t| 
      t.string :name 

      t.timestamps null: false 
     end 
     end 
    end 

     class CreateAppointments < ActiveRecord::Migration 
     def change 
     create_table :appointments do |t| 
      t.date :date_appointment 
      t.references :doctor, index: true, foreign_key: true 
      t.references :patient, index: true, foreign_key: true 

      t.timestamps null: false 
     end 
     end 
    end 

有了这个，我想创建一个表单上插入约会表记录，这样我可以访问并提交表单后得到任何医生或病人的姓名。

<%= form_for(@appointment) do |f| %> 
<%= f.label :date, "Choose a date for your appointment" %> 
<%= f.collection_select(:doctor_id, Doctor.all, :id, :name, prompt: true) %> 
<%= f.submit %> 
<% end %> 

的数据被插入，但是当我调用Show“模板”是给我的错误，指出该参数医生“零”，即使它有一个值。

<%= @appointment.doctor.name %> 

而这里的任命控制器数据

 class AppointmentsController < ApplicationController 

     def index 
     end 

     def show 

     end 

     def new 
      @appointment = Appointment.new 
     end 

     def create 
      @appointment = Appointment.new(appointment_params) 
      if @appointment.save 
       redirect_to @appointment 
      else 
       render "New" 
      end 
     end 

     private 

     def appointment_params 
      params.require(:appointment).permit(:date, :doctor_id, :patient_id) 
     end 

     def find_appointment 
      @appointment = Appointment.find(params[:id]) 
     end 



     end 

我想要做的是基本能够根据该行的属性值来呈现或显示医生，患者的姓名是正在使用表单创建新行后创建。

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

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

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

谢谢你的时间！

Answer 1

也许我错过了一些东西，但是你忘了设置@appointment var吗？

def show 
    @appointment = Appointment.find(params['id']) 
end