class Programa < ActiveRecord::Base
  attr_accessible :descripcion,:nombre,:roles_attributes
  has_many :roles,:dependent => :restrict
  accepts_nested_attributes_for :roles
    ...
end

class Role < ActiveRecord::Base
  attr_accessible :description,:name,:programa_id
  belongs_to :programa
    ...
end

它适用于rails控制台：

> params = { programa: { nombre: 'nuevo',roles_attributes: [ {name: 'role1'},{name: 'role2'}] }}
> p = Programa.create(params[:programa])
> p
 => #<Programa id: 7,nombre: "nuevo",descripcion: nil,created_at: "2013-10-09 14:07:46",updated_at: "2013-10-09 14:07:46">
> p.roles
 => [#<Role id: 15,name: "role1",description: nil,updated_at: "2013-10-09 14:07:46",programa_id: 7>,#<Role id: 16,name: "role2",programa_id: 7>]

但我不能在app / views / programas / _form中使它工作：

<%= form_for(@programa) do |f| %>
  <%= render 'shared/form_error_messages',object: f.object %>
  <div class="field">
    <%= f.label :nombre %>
    <%= f.text_field :nombre %>
  </div>
  <div class="field">
    <%= f.label :descripcion %>
    <%= f.text_field :descripcion %>
  </div>

  <% f.fields_for :roles do |builder| %>
    <div class="field">
      <%= builder.label :name %>
      <%= builder.text_field :name %>
    </div>
    <div class="field">
      <%= builder.label :description %>
      <%= builder.text_field :description %>
    </div>
  <% end %>

  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

还有什么我必须添加或删除,以使我的表单显示角色嵌套属性？

这是我的程序控制器：

class ProgramasController < ApplicationController
  # GET /programas
  # GET /programas.json
  def index
    @programas = Programa.all

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

  # GET /programas/1
  # GET /programas/1.json
  def show
    @programa = Programa.find(params[:id])

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

  # GET /programas/new
  # GET /programas/new.json
  def new
    @programa = Programa.new
    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @programa }
    end
  end

  # GET /programas/1/edit
  def edit
    @programa = Programa.find(params[:id])
  end

  # POST /programas
  # POST /programas.json
  def create
    @programa = Programa.new(params[:programa])

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

  # PUT /programas/1
  # PUT /programas/1.json
  def update
    @programa = Programa.find(params[:id])

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

  # DELETE /programas/1
  # DELETE /programas/1.json
  def destroy
    @programa = Programa.find(params[:id])
    @programa.destroy

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

我只希望嵌套属性只显示在编辑和显示操作中.