ruby-on-rails-3 - simple_form_for错误: undefined method - associated models

Question

在我的 Rails 应用程序中，我有两个关联的模型，称为杂志和文章。

杂志

class Magazine < ActiveRecord::Base
  has_many :articles
end

文章

class Article < ActiveRecord::Base
  belongs_to :magazine
end

路线

Magazineapp::Application.routes.draw do
  resources :magazines do
    resources :articles
  end
end

schema.rb

create_table "articles", :force => true do |t|
  t.string   "title"
  t.string   "author"
  t.integer  "magazine_id"
  t.datetime "created_at"
  t.datetime "updated_at"
end

create_table "magazines", :force => true do |t|
  t.string   "title"
  t.datetime "created_at"
  t.datetime "updated_at"
end

我正在尝试从文章的新页面创建与杂志关联的新文章。因此，我在杂志的显示页面中创建了一个链接，将所选杂志传递到新文章的页面。

views/magazines/show.html.erb

<p id="notice"><%= notice %></p>
<p>
  <b>Title:</b>
  <%= @magazine.title %>
</p>

<%= link_to 'Edit', edit_magazine_path(@magazine) %> |
<%= link_to 'Back', magazines_path %> |
<%= link_to 'New Article', new_magazine_article_path(@magazine) %>

文章新页面中呈现的部分内容是:

views/articles/_form.html.erb

<%= simple_form_for([@magazine, @article]) do |f| %>
  <%= f.error_notification %>

  <div class="inputs">
    <%= f.input :title %>
    <%= f.input :author %>
  </div>

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

文章 Controller 的创建方法是:

def create

  @magazine = Magazine.find(params[:magazine_id])    
  @article = @magazine.articles.create(params[:article])

  respond_to do |format|
    if @article.save
      format.html { redirect_to(@article, :notice => 'Article was successfully created.') }
      format.xml  { render :xml => @article, :status => :created, :location => @article }
    else
      format.html { render :action => "new" }
      format.xml  { render :xml => @article.errors, :status => :unprocessable_entity }
    end
  end
end

但是当我尝试创建与该杂志相关的新文章时，我收到错误消息:

Showing /home/wilson/magazineapp/app/views/articles/_form.html.erb where line #1 raised:

undefined method `articles_path' for #<#<Class:0x00000001944070>:0x00000001926ed0>
Extracted source (around line #1):

1: <%= simple_form_for([@magazine, @article]) do |f| %>
2:   <%= f.error_notification %>
3: 
4:   <div class="inputs">

Request

Parameters:

{"magazine_id"=>"2"}

耙动路线

    magazine_articles GET    /magazines/:magazine_id/articles(.:format)          {:action=>"index", :controller=>"articles"}
                      POST   /magazines/:magazine_id/articles(.:format)          {:action=>"create", :controller=>"articles"}
 new_magazine_article GET    /magazines/:magazine_id/articles/new(.:format)      {:action=>"new", :controller=>"articles"}
edit_magazine_article GET    /magazines/:magazine_id/articles/:id/edit(.:format) {:action=>"edit", :controller=>"articles"}
     magazine_article GET    /magazines/:magazine_id/articles/:id(.:format)      {:action=>"show", :controller=>"articles"}
                      PUT    /magazines/:magazine_id/articles/:id(.:format)      {:action=>"update", :controller=>"articles"}
                      DELETE /magazines/:magazine_id/articles/:id(.:format)      {:action=>"destroy", :controller=>"articles"}
            magazines GET    /magazines(.:format)                                {:action=>"index", :controller=>"magazines"}
                      POST   /magazines(.:format)                                {:action=>"create", :controller=>"magazines"}
         new_magazine GET    /magazines/new(.:format)                            {:action=>"new", :controller=>"magazines"}
        edit_magazine GET    /magazines/:id/edit(.:format)                       {:action=>"edit", :controller=>"magazines"}
             magazine GET    /magazines/:id(.:format)                            {:action=>"show", :controller=>"magazines"}
                      PUT    /magazines/:id(.:format)                            {:action=>"update", :controller=>"magazines"}
                      DELETE /magazines/:id(.:format)                            {:action=>"destroy", :controller=>"magazines"}

如何解决这个问题？在这种情况下，传递给 simple_form_for 的正确参数是什么？

Answer 1

当您有嵌套资源时，您必须确保始终在请求之间传递更高级别的资源。

您的路线将是您使用 rake 路线注意到的路线。

表格应该是这样的:

<%= simple_form_for([@magazine, @article]) do |f| %>
  <%= f.error_notification %>

  <div class="inputs">
    <%= f.input :title %>
    <%= f.input :author %>
  </div>    
  <div class="actions">
    <%= f.button :submit %>
  </div>
<% end %>

这样，您现在就必须在文章 Controller 和文章 View 页面上的任何地方使用新路由，其中​​包括杂志本身。

您在 Controller 中的创建操作将是:

def create

  @magazine = Magazine.find(params[:magazine_id])    
  @article = @magazine.articles.create(params[:article])

  respond_to do |format|
    if @article.save
      format.html { redirect_to([@magazine,@article], :notice => 'Article was successfully created.') }
      format.xml  { render :xml => @article, :status => :created, :location => @article }
    else
      format.html { render :action => "new" }
      format.xml  { render :xml => @article.errors, :status => :unprocessable_entity }
    end
  end
end

所以现在您的所有路线都应该引用@magazine。