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Account :: Posts #index中的NoMethodError

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我正在做Ruby101教程，但是出了点问题 .

rails日志：

ActionView::Template::Error (undefined method `title' for nil:NilClass):
13:       <% @posts.each do |post| %>
14:         <tr>
15:           <td> <%= post.content %> </td>
16:           <td> <%= post.group.title %> </td>
17:           <td> <%= post.updated_at %> </td>
18:           <td> <%= link_to('Edit', edit_group_post_path(post.group, post), class: "btn btn-default btn-xs") %></td>
19:           <td> <%= link_to('Delete', group_post_path(post.group, post), method: :delete, data: { confirm: "Are you sure?" }, class: "btn btn-default btn-xs") %></td>

app / views / account / posts / index.html.erb：16：在_app_views_account_posts_index_html_erb___92982360307258762_69918747126320'app / views / account / posts / index.html.erb：13：in_app_views_account_posts_index_html_erb ___92982360307258762_69918747126320'渲染/home/zedong/.rvm/gems救援/布局中的/ruby-2.3.1/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/template_error.html.erb渲染/home/zedong/.rvm/gems/ruby-2.3.1 /gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_source.html.erb呈现/home/zedong/.rvm/gems/ruby-2.3.1/gems/actionpack-5.0.0.1/lib /action_dispatch/middleware/templates/rescues/_source.html.erb(3msms）渲染/home/zedong/.rvm/gems/ruby-2.3.1/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates /rescues/_trace.html.erb呈现/home/zedong/.rvm/gems/ruby-2.3.1/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb(2.5 ms）渲染/home/zedong/.rvm/gems/ruby -2.3.1 / gems / actionpack-5.0.0.1 / lib / action_dispatch / middleware / templates / rescues / _request_and_response.html.erb呈现/home/zedong/.rvm/gems/ruby-2.3.1/gems/actionpack-5.0 .0.1 / lib / action_dispatch / middleware / templates / rescues / _request_and_response.html.erb(0.7ms）呈现/home/zedong/.rvm/gems/ruby-2.3.1/gems/actionpack-5.0.0.1/lib/action_dispatch /middleware/templates/rescues/template_error.html.erb救援/布局（21.5ms）

而group.rb：

class Group < ActiveRecord::Base
  belongs_to :user
  has_many :posts
  validates :title, presence: true
  has_many :group_relationships
  has_many :members, through: :group_relationships, source: :user
end

post.rb：

class Post < ApplicationRecord
  validates :content, presence: true
  belongs_to :user
  belongs_to :group

  scope :recent, -> {order("created_at DESC")}
end

因为我第二次做这个教程，所以我将它与第一次的代码进行比较 . 我试图逐个复制文件以找到问题，但它无法正常工作 . 顺便说一句，当我想实现eidt和删除按钮时，出了点问题 .

项目在这里：github

ruby-on-rails ruby-on-rails-5

1 回答

  • 1

    您需要确保 post 与 post 关联，您可以使用 try 仅用于呈现纯内容（因此它不呈现任何内容，但不会引发异常）：

    <td> <%= post.group.try(:title) %> </td>

    并且 if 控制流以有条件地呈现链接：

    <% if post.group.present? %>
  <td> <%= link_to('Edit', edit_group_post_path(post.group, post), class: "btn btn-default btn-xs") %></td>
  <td> <%= link_to('Delete', group_post_path(post.group, post), method: :delete, data: { confirm: "Are you sure?" }, class: "btn btn-default btn-xs") %></td>
<%end%>
    回复于

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