Rails 4 form_for双嵌套注释 [英] Rails 4 form_for double nested comments

问题描述

首先，我已经找到了一些非常有用的答案（请参阅下面的链接），但我仍然在努力完成这项工作。我一直没有编程很久，这肯定是令我感到舒服的自称理解。

我有三种模式。举例来说，我会称它们为树，树皮，雕刻（评论）。我试图为用户添加一个简单的表单部分以提交新评论（雕刻）。

以下设置会产生错误：

NoMethodError在/ trees / 1
未定义方法`tree'for nil：NilClass

控制器

  class TreesController< ApplicationController 
 def show 
 @barks = Bark.where（tree_id：@ tree.id）
 @ engraving = Engraving.new（：bark => @bark）
 end 
结束
 
类BarksController< ApplicationController 
 def show 
 @ engravin = Engraving.new（：bark => @bark）
 @engravings = Engraving.where（bark_id：@ bark.id）
 end 
结束
 
类EngravingsController< ApplicationController 
 def show 
 @ bark = Bark.find（params [：bark_id]）
 @engraving = Engraving.new（params [：engraving]）
 end 
结束
 $ b $ def创建
 @bark = Bark.find（params [：bark_id]）
 @engraving = Engraving.new（params [：engraving]）
 @ engraving.user_id = current_user.id 
 
 
 respond_to do | format | 
 if @ engraving.save 
 format.html {redirect_to tree_bark_path（@tree，@bark），注意：'评论已成功创建。'} 
 format.json {render action：'show '，status：：created，location：@engraving} 
 else 
 format.html {render action：'new'} 
 format.json {render json：@ engraving.errors，status： ：unprocessable_entity} 
 end 
 end 
  

end

模型

  class Tree< ActiveRecord :: Base 
 belongs_to：user 
 has_many：barks 
 has_many：雕刻，通过:: barks 
 end 
 
 class Bark< ActiveRecord :: Base 
 belongs_to：用户
 belongs_to：树
 has_many：雕刻
 
代表：title，：link，：to => ：tree，：prefix => true 
 
 def new_engraving_path 
 Rails.application.routes.url_helpers.new_tree_bark_engraving_path（book，self）
 end 
 $ b $ def serializable_hash（* args）
 super.merge'new_engraving_path'=> new_engraving_path 
 end 
 end 
 
 class Engraving< ActiveRecord :: Base 
 belongs_to：user 
 belongs_to：bark 
 
 delegate：tree，：to => ：树皮，：前缀=> true 
 
 def to_edit_path 
 Rails.application.routes.url_helpers.edit_tree_bark_engraving_path bark_tree，bark，self 
 end 
 
 def to_path 
 Rails。 application.routes.url_helpers.tree_bark_engraving_path bark_tree，bark，self 
 end 
 
 def serializable_hash（* args）
 super.merge'path'=> to_path，'edit_path'=> to_edit_path 
 end 
 end 
  

在视图中调用表单

在树显示页面上，我将所有树皮填充到那里。点击一个Bark元素打开一个模式，显示Bark.content和Engravings。在最后一个Engraving下，我希望有一个text_area表单来创建一个新的Engraving，并将其添加到这片树皮中。

 ＃trees\show.html.erb 
 <％= render @barks％> 
 
＃barks\_bark.html.erb 
 <％=渲染部分：'barks / modal'，当地人：{bark：bark}％> 
 
＃barks \modal.html.erb 
 <％渲染部分：'/ engravings / simpleForm'，：collection => bark.engravings％> 
 
＃表格部分
 
 <％= form_for @engraving，：url => （new_tree_bark_engraving_path（：tree_id => @ bark.tree，：bark_id => @ bark.id））do | f | ％GT; 
<％= f.hidden_​​field：bark_id％> 
 
< div class =field> 
<％= f.text_area：content％> 
< / div> 
 
< div class =actions> 
<％= f.submit％> 
< / div> 
<％end％> 
  

路线

  getpages / home
 
资源：树做
集合做
获得'搜索'
发布'load_from_api'
结束
资源：树皮做
资源：雕刻
结束
结束
资源：树皮做
资源：雕刻
结束
 
 roottrees＃index
  

---

来源

Rails路由嵌套form_for错误

两次嵌套资源Form_For问题

form_for嵌套资源

解决方案

您的错误消息 NoMethodError at / trees / 1 nil：NilClass 的未定义方法'tree'表示您必须调用某个地方 .tree 在 nil 对象上。我能看到发生的唯一情况是部分形式。我假设 @ bark.tree 失败。

从您的问题中不清楚您是哪个控制器正在渲染部分内容，但最可能的原因是 @bark 未被传递到表单中。确保你传递了 @bark 到你的部分，这里是一个例子：

 <％=渲染部分：form，当地人：{bark：@bark}％> 
  

First of all, I've found some very helpful answers already (see links below), but I'm still struggling to make this work. I haven't been programming for long, and this is definitely stretching what I feel comfortable claiming to understand.

I have three models. For example's sake, I'll call them Tree, Bark, Engraving (the comments). I'm trying to add a simple form partial for users to submit new comments (engravings).

The below setup is producing the error:

NoMethodError at /trees/1 undefined method `tree' for nil:NilClass

Controllers

class TreesController < ApplicationController
  def show
   @barks = Bark.where(tree_id: @tree.id)
   @engraving= Engraving.new( :bark=> @bark)  
  end
end

class BarksController < ApplicationController
  def show
   @engravin= Engraving.new( :bark=> @bark)
   @engravings = Engraving.where(bark_id: @bark.id)  
  end
end

class EngravingsController < ApplicationController
  def show
   @bark= Bark.find(params[:bark_id])
   @engraving = Engraving.new(params[:engraving])  
  end
end

def create
@bark = Bark.find(params[:bark_id])
@engraving = Engraving.new(params[:engraving])
@engraving.user_id = current_user.id


respond_to do |format|
  if @engraving.save
    format.html { redirect_to tree_bark_path(@tree, @bark), notice: 'Comment was       successfully created.' }
    format.json { render action: 'show', status: :created, location: @engraving}
  else
    format.html { render action: 'new' }
    format.json { render json: @engraving.errors, status: :unprocessable_entity }
  end
end

end

Models

class Tree < ActiveRecord::Base
  belongs_to :user
  has_many :barks
  has_many :engravings, through: :barks
end

class Bark< ActiveRecord::Base
  belongs_to :user
  belongs_to :tree
  has_many :engravings

  delegate :title, :link, :to => :tree, :prefix => true

  def new_engraving_path
    Rails.application.routes.url_helpers.new_tree_bark_engraving_path(book, self)
  end

  def serializable_hash(*args)
    super.merge 'new_engraving_path' => new_engraving_path
  end
end

class Engraving< ActiveRecord::Base
  belongs_to :user
  belongs_to :bark

  delegate :tree, :to => :bark, :prefix => true

  def to_edit_path
    Rails.application.routes.url_helpers.edit_tree_bark_engraving_path bark_tree, bark, self
  end

  def to_path
    Rails.application.routes.url_helpers.tree_bark_engraving_path bark_tree, bark, self
  end

  def serializable_hash(*args)
    super.merge 'path' => to_path, 'edit_path' => to_edit_path
  end
end

Calling the Form in a View

On the Tree show page, I have all the Bark populating there. Clicking on an Bark element opens a modal, where the Bark.content and Engravings are shown. Under the last Engraving, I want to have a text_area form to create a new Engraving, and add it to this "piece" of bark.

# trees\show.html.erb
<%= render @barks %>

# barks\_bark.html.erb
<%= render partial: 'barks/modal', locals: { bark: bark} %>

# barks\modal.html.erb
<% render partial: '/engravings/simpleForm', :collection => bark.engravings %>

# Form partial

  <%= form_for @engraving, :url => (new_tree_bark_engraving_path(:tree_id => @bark.tree, :bark_id => @bark.id)) do |f| %>
    <%= f.hidden_field :bark_id %> 

     <div class="field">
      <%= f.text_area :content %>
     </div>

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

Routes

    get "pages/home"

    resources :trees do
      collection do
        get 'search'
        post 'load_from_api'
      end
    resources :barks do
      resources :engravings
    end
  end
    resources :barks do
      resources :engravings
    end

  root "trees#index"

---

Other Answer Sources

Rails Routing Error for nested form_for

Twice Nested Resource Form_For Issue

form_for with nested resources

解决方案

Your error message NoMethodError at /trees/1 undefined method 'tree' for nil:NilClass means that somewhere you must be calling .tree on a nil object. The only place I can see that happening is in the form partial. I'm assuming that @bark.tree is failing.

From your question it is not clear which controller you are rendering the partial from, but the most likely cause is that @bark is not being passed into the form. Make sure that you are passing @bark into your partial, here is an example:

<%= render partial: "form", locals: {bark: @bark} %>

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