Rails的嵌套屬性（accepts_nested_attributes_for）

Question

我有這樣的一對多的關係形成

> 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, created_at: "2013-10-09 14:07:46", updated_at: "2013-10-09 14:07:46", programa_id: 7>, #<Role id: 16, name: "role2", description: nil, created_at: "2013-10-09 14:07:46", updated_at: "2013-10-09 14:07:46", programa_id: 7>] 

但我不能使其在應用程序的工作/ views/programas/_form：

<%= 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 %> 

還有其他什麼，我必須添加或刪除，以使我的窗體顯示角色n ested屬性？

這是我的計劃成控制器：

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 

我只是想在編輯中顯示，只顯示操作嵌套屬性。

Answer 1

嵌套屬性的表單將只顯示實際上是否有數據顯示，即。如果您的Programa實例有一個或多個與之關聯的角色。

這可以像控制器中的@programa.roles.build一樣簡單，在渲染表單之前添加一個新角色。任何現有的角色將被渲染。

編輯：您還需要實際呈現表單，即。 <%= f.fields_for（注意丟失=）。