Rails 4 form_for雙重嵌套註釋

Question

首先，我已經找到了一些非常有幫助的答案（請參閱下面的鏈接），但我仍然努力做到這一點。我沒有長時間的編程，而且這絕對是我舒服自稱理解的東西。

我有三種模式。舉例來說，我會稱它們爲樹，樹皮，雕刻（評論）。我正在嘗試爲用戶添加一個簡單的表單部分以提交新評論（雕刻）。

的下面設置是製造誤差：

NoMethodError在/樹木/ 1 未定義的方法`樹」的零：NilClass

控制器

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 

端

模型

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 

在視圖中調用窗體

在樹顯示頁面上，我將所有樹皮填充到那裏。點擊一個Bark元素打開一個模式，顯示Bark.content和Engravings。在最後的雕刻下，我想要一個text_area表單來創建一個新的雕刻，並將其添加到這片「樹皮」中。

# 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 %> 

路線

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" 

---

對方的回答來源

Rails Routing Error for nested form_for

Twice Nested Resource Form_For Issue

form_for with nested resources

Answer 1

您的錯誤消息NoMethodError at /trees/1 undefined method 'tree' for nil:NilClass意味着某處您必須致電.tree對象nil。我能看到發生的唯一情況是部分形式。我假設@bark.tree失敗。

從你的問題，你不清楚你是從哪個控制器渲染的部分，但最可能的原因是@bark沒有被傳遞到窗體。請確保您傳遞@bark到您的部分，這裏有一個例子：

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

Answer 2

你在你的trees#show action definining @barks，但從來沒有@bark

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

所以@bark爲零。