Question

我无法理解并解决这个错误.plz帮帮我。下面是我的错误。

ProductsController中的NoMethodError＃创建未定义的方法`产品＆＃39;对于nil：NilClass（来自productscontroller＆＃39; s＆＃34; @product = @ user.products.build（products_params）＆＃34）

  class ProductsController < ApplicationController
  before_action :signed_in_user,only:[:new,:create]
  before_action :find_user_object,except:[:create]

  def index
    @products = @user.products.all
  end

  def show
    @product = @user.product.build.find(params[:id])
  end

  def new
    @user = User.find(params[:user_id])
    # => 多分before action化させる方が良い
    #urlでproducts/newなっててUserのidが取れてない。
    redirect_to signin_url, notice:"U have to sign in to publish your furniture." unless sign_in @user
    @product = Product.new
  end

  def create
    @product = @user.products.build(products_params)
    if @product.save
      flash[:success] = "You could add new item:)"
      redirect_to @user #後にaction: :indexに変更したい
    else
      flash.now[:error] = "You couldn't add an item."
      render 'new'
    end
  end

  def edit
  end

  def update
    if @product.update_attributes(products_params)
      flash[:success] =  "You updated your product info"
      redirect_to @products
    else
      flash.now[:error] = "couldn't update :("
      redirect_to products_edit_path
    end
  end

  def destroy
    #あった方がいいかもしれない@user = Product.find(params[:id])
    @product.destroy
    redirect_to root_url
  end




  private

  def products_params
    params.require(:product).permit(:id,:name,:kind,:size,:discription,:price)
  end


  #before_action
  def signed_in_user
    redirect_to signin_url, notice:"Please sign in." if signed_in? 
  end

  def find_user_object
    @user = User.find_by(params[:user_id])
  end

end

以上是productscontroller.below是用户控制器。

class UsersController < ApplicationController
  include UsersHelper
  before_action :signed_in_user,only:[:edit,:update]
  before_action :correct_user,only:[:edit,:update]

  def show
    @user = User.find(params[:id])
    sign_in @user if signed_in?
  end

  def new
    @user = User.new
  end

  def create
    @user = User.new(user_params)
    if @user.save!
      sign_in @user
        flash[:success] = "Success creating user"
        redirect_to @user
    else
      flash.now[:error] = "couldn't create...."
      render 'new'
    end
  end

  def edit
  end

  def update
    if @user.update_attributes(user_params)
      flash[:success] = "User info was updated"
      redirect_to user_url
    else
      flash.now[:error] = "You could not edit your profile"
      render 'edit'
    end
  end

  def destroy
    #あった方がいいかもしれない@user = Product.find(params[:id])
    @user.destroy
    redirect_to root_url 
  end

  private
  def user_params
    params.require(:user).permit(:id,:user_id,:name,:email,:username,:status,:from,:when,:password,:password_confirmation)
  end

  #before_aciton
  def correct_user
    @user = User.find(params[:id])
    redirect_to signin_url,notice:"You have to sign in to edit your profile."  unless current_user=(@user)
  end

  def signed_in_user
    redirect_to signin_url, notice:"Please sign in." if signed_in? 
  end

end

以下是routes.rb。

   KaguShop::Application.routes.draw do
  resources :users,only:[:show,:new,:create,:edit,:update,:destroy] do
    resources :products,only:[:index,:new,:create,:destroy,:show,:new,:edit,:update]
  end

  resources :sessions,only:[:new,:create,:destroy]
  resources :carts,only:[:new,:create,:destroy]#,:showに関しては恐らくいらない。newで既にオブジェクトも作る


  root 'products#index'
  match '/signup', to:'users#new',via:'get'
  match '/signin', to:'sessions#new', via:'get'
  match '/signout', to:'sessions#destroy', via:'delete'
  match '/contact', to:'nomal_pages#contact', via:'get'

  # The priority is based upon order of creation: first created -> highest priority.
  # See how all your routes lay out with "rake routes".

  # You can have the root of your site routed with "root"
  # root 'welcome#index'

  # Example of regular route:
  #   get 'products/:id' => 'catalog#view'

  # Example of named route that can be invoked with purchase_url(id: product.id)
  #   get 'products/:id/purchase' => 'catalog#purchase', as: :purchase

  # Example resource route (maps HTTP verbs to controller actions automatically):
  #   resources :products

  # Example resource route with options:
  #   resources :products do
  #     member do
  #       get 'short'
  #       post 'toggle'
  #     end
  #
  #     collection do
  #       get 'sold'
  #     end
  #   end

  # Example resource route with sub-resources:
  #   resources :products do
  #     resources :comments, :sales
  #     resource :seller
  #   end

  # Example resource route with more complex sub-resources:
  #   resources :products do
  #     resources :comments
  #     resources :sales do
  #       get 'recent', on: :collection
  #     end
  #   end

  # Example resource route with concerns:
  #   concern :toggleable do
  #     post 'toggle'
  #   end
  #   resources :posts, concerns: :toggleable
  #   resources :photos, concerns: :toggleable

  # Example resource route within a namespace:
  #   namespace :admin do
  #     # Directs /admin/products/* to Admin::ProductsController
  #     # (app/controllers/admin/products_controller.rb)
  #     resources :products
  #   end
end

并且，产品型号有.... ①name②size③kind④dcription⑤价格（当然id但没有product_id）

用户模型...... ①name②email③username④password⑤password_confirmation⑥from⑦when⑧status

Answer 1

你有before_action :find_user_object,except:[:create]。这意味着除了@user之外的所有操作都会设置create。但您需要在@user操作中设置create。所以你应该删除except:[:create]并离开：

before_action :find_user_object

Answer 2

在ProductsController你有

before_action :find_user_object,except:[:create]

因此，@user操作中未设置create因为例外。

Answer 3

在show方法中，您build然后find在show方法下面看它应该是这样的

请检查user_id表中是否还有products

class ProductsController < ApplicationController

  before_action :find_user_object

  def show
    @product = @user.products.find(params[:id])
  end

end

undefined方法`产品'为nil：ProductsController #crera中的NilClass NoMethodError

3 个答案: