如何从rails中的模型关系中获取值？

Question

我有两个模型：

class Doctor ...
has_many :specialties
end

class Specialty
belongs_to :doctor
end

在医生索引视图中，我试图显示对象的所有属性以及与名称的专业关系中的属性。但是当我渲染索引页面时，专业对象的属性显示为空数组。

index.html.erb

....
<% @doctors.each do |doctor| %>
  <tr>
    <td><%= doctor.name %></td>
    <td><%= doctor.specialties %></td>
    <td><%= doctor.dschedule %></td>
    <td>#</td>
    <td>
       <%= link_to .... %>
    </td>

  </tr>
<% end %>
....

class DoctorsController < ApplicationController
  # GET /doctors
  # GET /doctors.json
  def index

    @doctors = Doctor.all

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @doctors }
    end
  end

  # GET /doctors/1
  # GET /doctors/1.json
  def show
    @doctor = Doctor.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @doctor }
    end
  end

  # GET /doctors/new
  # GET /doctors/new.json
  def new
    @doctor = Doctor.new    
    1.times { @doctor.build_schedule }
    1.times { @doctor.branches.build }
    1.times { @doctor.specialties.build }

    @specialties = Specialty.all
    @branches = Branch.all



    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @doctor }
    end
  end

  # GET /doctors/1/edit
  def edit
    @doctor = Doctor.find(params[:id])
  end

  # POST /doctors
  # POST /doctors.json
  def create
    @doctor = Doctor.new(params[:doctor])

    respond_to do |format|
      if @doctor.save
        format.html { redirect_to @doctor, notice: 'Doctor was successfully created.' }
        format.json { render json: @doctor, status: :created, location: @doctor }
      else
        format.html { render action: "new" }
        format.json { render json: @doctor.errors, status: :unprocessable_entity }
      end
    end
  end

  # PUT /doctors/1
  # PUT /doctors/1.json
  def update
    @doctor = Doctor.find(params[:id])

    respond_to do |format|
      if @doctor.update_attributes(params[:doctor])
        format.html { redirect_to @doctor, notice: 'Doctor was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: "edit" }
        format.json { render json: @doctor.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /doctors/1
  # DELETE /doctors/1.json
  def destroy
    @doctor = Doctor.find(params[:id])
    @doctor.destroy

    respond_to do |format|
      format.html { redirect_to doctors_url }
      format.json { head :no_content }
    end
  end
end

我该如何解决这个问题？