更好的方式向foreign_key值传递给控制器​​的Rails [英] The better way to pass the foreign_key value to the Rails controller

问题描述

这是近一个星期，因为我已经开始在形式的深入挖掘，协会，散列符号......但似乎没有你的帮助我解决不了这个难题。

It's been almost a week since I've began to dig deeper in forms , associations , hashes , symbols... But it seems I cannot solve the puzzle without your help .

我工作的一个项目显示不同的画廊的内容。的基本思想是，当用户看到画廊的名称（名称链接）以便能够点击选择之一。然后，属于该库中的所有图像，被显示。在底部应该有一个链接添加图片在这个画廊。

I am working on a project for displaying different galleries content . The basic idea is when the user sees the names of galleries (names are links ) to be able to click on chosen one. Then all the images ,that belong to this gallery , are displayed . On the bottom there should be a link "Add image in this gallery" .

我的模型：

 class Gallery < ActiveRecord::Base
attr_accessible  :name
has_many :pictures 
 end


class Picture < ActiveRecord::Base 
attr_accessible  :image 
belongs_to :gallery
 end

我建立了gallery_id指数为'图片'表。

I have created index on gallery_id for the 'pictures' table .

我的大问题在这里出现，如何将gallery_id传递给控制器​​的动作'新'。正如我在敏捷​​Web开发使用Rails已经看到了它可能是：结果
    ＆LT;％=的link_to添加图片在这里...，new_picture_path（：gallery_id => @ gallery.id）％>

My big problem appears here , how to pass the gallery_id to the controller's action 'new' . As I've seen in "Agile web development with Rails" it could be :
<%= link_to 'Add a picture here...',new_picture_path(:gallery_id=>@gallery.id) %>

，因为它似乎在这种情况下，foreign_key：gallery_id在浏览器的地址栏露出。第二个问题是：gallery_id可用于控制新的功能，但消失为创造功能（导致一个错误不能没有一个ID找到画廊）。
  当我在为_form图片添加一个隐藏字段的问题消失了，在我的情况：

As it seems in this case the foreign_key :gallery_id is exposed in the URL bar of the browser . The second problem is that :gallery_id is available for the controller 'new' function , but "disappears" for the 'create' function (causing an error " Couldn't find Gallery without an ID ") . The problem is gone when I add a hidden field in the _form for pictures , in my case :

<%= form_for(@picture)   do |f| %>
<div class="field"> 
      <%= f.hidden_field :gallery_id , :value=>params[:gallery_id] %>
<%= f.label :image %><br />
<%= f.file_field :image %>
</div>

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

下面是我的定义中的图片控制器：

Here are my definitions in the 'pictures' controller :

def new
@gallery=Gallery.find(params[:gallery_id])
@picture=@gallery.pictures.build 
 end


def create
   @gallery = Gallery.find(params[:gallery_id])  
   @picture = @gallery.pictures.new(params[:picture])
  if @picture.save
     redirect_to(@picture, :notice => 'Picture was successfully created.')
  else    
     redirect_to(galleries ,:notice => 'Picture was NOT created.')
  end

 end

和finaly的​​的link_to定义为show.html.erb画廊：

And finaly the link_to definition in show.html.erb for galleries:

<% for picture in selpics(@gallery) %>
 <div id= "thumb" > 
 <%= image_tag picture.image %>
 </div>
<% end %>

 <%= link_to 'Add a picture here...',new_picture_path(:gallery_id=>@gallery.id) %>

下面是提交图像前的调试输出：
    ！---地图：::的ActiveSupport HashWithIndifferentAccess
    gallery_id：6
    动作：新
    控制器：图片

Here is the debug output before submitting the image : --- !map:ActiveSupport::HashWithIndifferentAccess gallery_id: "6" action: new controller: pictures

和提交创建按钮（带发生异常）后：

and after submitting the 'create' button (with exception raised ) :

{"utf8"=>"✓",
 "authenticity_token"=>"IGI4MfDgbavBShO7R2PXIiK8fGjkgHDPbI117tcfxmc=",
 "picture"=>{"image"=>"wilsonblx.png"},
 "commit"=>"Create"}

正如你所见，有没有像gallery_id中的图片哈希值。

As you see , there is nothing like "gallery_id" in the "pictures" hash .

总结我的问题给你：

1. 有没有办法来传​​递foreign_key没有hidden_​​field？

1. Is there a way to pass the foreign_key without hidden_field ?

莫非我躲在通过某种方式在地址栏显示的外键的形式？

Could I hide somehow passing the foreign key form showing in the URL bar ?

有没有使用的link_to'传递参数的方法吗？

Is there an alternative on passing arguments using 'link_to' ?

感谢您。

推荐答案

您可能要考虑阅读的Rails指南嵌套的资源：

You may want to consider reading the Rails Guide on nested resources:

<一个href=\"http://guides.rubyonrails.org/routing.html#nested-resources\">http://guides.rubyonrails.org/routing.html#nested-resources

在一言以蔽之：

的routes.rb

routes.rb

resources :galleries do
  resources :pictures do
end
# Generates the routes: /galleries/:gallery_id/pictures

pictures_controller.rb

pictures_controller.rb

def new
  @gallery = Gallery.find(params[:gallery_id])
  @picture = Picture.new
end
def create
  @gallery = Gallery.find(params[:gallery_id]) # gallery_id is passed in the URL
  @picture = @gallery.build(params[:picture])
  if @picture.save
  # success
  else
  # fail
  end
end

图片/ new.html.erb

pictures/new.html.erb

<%= form_for [@gallery, @picture] do |f| %>
  <div class="field"> 
    <%= f.hidden_field :gallery_id , :value=>params[:gallery_id] %>
    <%= f.label :image %><br />
    <%= f.file_field :image %>
  </div>

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

<% end %>

好吧，所以gallery_id还是通过URL过去了，但我实在看不出什么不妥。你必须从某个地方传了吧？你真的只有3理智的选择在哪里把它传递：一个隐藏字段作为查询字符串参数，或者卷起的URL（嵌套资源）内。 3，后者是恕我直言，最干净的方法。

Ok, so the gallery_id is still passed through the URL, but I don't really see anything wrong with that. You have to pass it somewhere, right? You really only have 3 sane choices on where to pass it: a hidden field, as a querystring parameter, or tucked away inside the URL (nested resource). Of the 3, the latter is IMHO the cleanest method.

如果你想使事情变得更简单了自己，我强烈建议寻找到何塞Valim的继承资源的宝石，需要照顾很多这样的样板污秽的你：

If you want to make things even easier on yourself, I highly recommend looking into Jose Valim's Inherited Resources gem that takes care of a lot of this boilerplate nastiness for you:

<一个href=\"https://github.com/josevalim/inherited_resources\">https://github.com/josevalim/inherited_resources

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