Ruby on rails - 未定义的局部变量或方法 ''welcome' for #<ActionDispatch：：Routing：：Mapper：0x007fd561953218&

Question

我遵循ruby on rails教程指南，但我一直有我的标题中所述的错误。我完全不知道它为什么会出现。

routes.rb

    Rails.application.routes.draw do
  # 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 ‘application#hello’ 
  # 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

application_controller.rb

class ApplicationController < ActionController::Base
  # Prevent CSRF attacks by raising an exception.
  # For APIs, you may want to use :null_session instead.
  protect_from_forgery with: :exception
  def hello  
    render text: “Hello”
  end
end

请给我建议，因为我一直在尝试，甚至重新安装一切基于Ruby on Rails教程。

Answer 1

问题在这一行root ‘application#hello’。看起来您的系统对单引号使用了错误的符号(您正在使用的是8216 unicode字符，您应该使用39)。同样在你的控制器render text: “Hello”会抛出一个错误。

应该是root 'application#hello'和render text: "Hello"

这可以在您的系统键盘设置中更改。不能更准确，因为我不知道你使用的是什么系统，但问题肯定是单引号的符号错误。