ruby-on-rails - 为 nil :NilClass on the view new 获取未定义的方法 `errors'

Question

我是 ruby​​ 的新手，正在学习，所以我一直在学习本教程 http://guides.rubyonrails.org/getting_started.html但是当我尝试添加错误消息时，我得到了 nil:NilClass 的未定义方法“错误”在这段代码中:

<h1>New Article</h1>
     <%= form_for :posts, url: posts_path do |f| %>
      <% if @post.errors.any? %> // <-- **HERE**
          <div id="error_explanation">
            <h2>
              <%= pluralize(@post.errors.count, "error") %> prohibited

这是我的 Controller :

class PostsController < ApplicationController
  def index
    @posts = Post.all
  end

  def new
    @posts = Post.all
  end

  def create
      @posts = Post.new(posts_params)
    if @posts.save
        redirect_to @posts
    else
        render 'new'
    end
  end

  def show
    @posts = Post.find(params[:id])
  end

  private
  def posts_params
    params.require(:posts).permit(:title, :description)
  end  
end

我的观点完全错误:

<h1>New Article</h1>
<%= form_for :posts, url: posts_path do |f| %>
<% if @post.errors.any? %>
    <div id="error_explanation">
      <h2>
        <%= pluralize(@post.errors.count, "error") %> prohibited
        this post from being saved:
      </h2>
      <ul>
        <% @post.errors.full_messages.each do |msg| %>
          <li><%= msg %></li>
        <% end %>
      </ul>
    </div>
  <% end %>
  <p>
    <%= f.label :title %><br>
    <%= f.text_field :title %>
  </p>

  <p>
    <%= f.label :description %><br>
    <%= f.text_area :description %>
  </p>

  <p>
    <%= f.submit %>
  </p>
<% end %>
<%= link_to 'Back', posts_path %>

My model: 



 class Post < ActiveRecord::Base

        validates :title, 
                :presence => {:message => "Title can't be blank." },
                :uniqueness => {:message => "Title already exists."},
                 length: { minimum: 5 }

        validates :description, 
        :presence =>{:message => "Description can't be blank." }
    end

有人可以帮助我吗？

Answer 1

您有以下内容:

<% if @post.errors.any? %>

但是在你的 Controller 中，你有:

 def new
    @posts = Post.new
  end

 def create
    @posts = Post.new(posts_params)
    ...
 end

在 Controller 中将 @posts 重命名为 @post。

因此，代码必须如下所示:

def new
    @post = Post.new
  end

 def create
    @post = Post.new(posts_params)
    ...
 end