ruby-on-rails - NoMethodError 未定义方法 ` ' 为 nil :NilClass

Question

我是 Rails 新手，从 http://guides.rubyonrails.org/getting_started.html 开始卡在 5.7 Showing Articles 并出现以下错误:

NoMethodError in Articles#show
Showing /home/jakub/workspace/blog/blog/app/views/articles/show.erb where line #3 raised:

undefined method `title' for nil:NilClass

来源在哪里:

 <p>
    <strong>Title:</strong>
    <%= @article.title %>
  </p>

  <p>

和articles_controller.rb是:

class ArticlesController < ApplicationController

  def index
    @articles = Article.all
  end

  def create
    @article = Article.new(article_params)

    @article.save
    redirect_to @article
  end

  private
  def article_params
    params.require(:article).permit(:title, :text)
  end

  def show
    @article = Article.find(params[:id])
  end

end

和rake routes命令带来:

        Prefix Verb   URI Pattern                  Controller#Action
welcome_contact GET    /welcome/contact(.:format)   welcome#contact
  welcome_index GET    /welcome/index(.:format)     welcome#index
       articles GET    /articles(.:format)          articles#index
                POST   /articles(.:format)          articles#create
    new_article GET    /articles/new(.:format)      articles#new
   edit_article GET    /articles/:id/edit(.:format) articles#edit
        article GET    /articles/:id(.:format)      articles#show
                PATCH  /articles/:id(.:format)      articles#update
                PUT    /articles/:id(.:format)      articles#update
                DELETE /articles/:id(.:format)      articles#destroy
           root GET    /                            welcome#index

知道是什么导致了这个问题吗？ 我应该在哪里寻找？

Answer 1

您的show 操作是私有(private)的，因此不能在 View 中使用实例变量@post。将其移至公共(public)范围，问题应该得到解决。