Question

我正在做Ruby101教程，但是出了点问题。

rails log：

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:in block in _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＆＃39; 在救援/布局中渲染/home/zedong/.rvm/gems/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(3.7ms）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(2.5ms）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）在救援/布局（21.5ms）内呈现/home/zedong/.rvm/gems/ruby-2.3.1/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/template_error.html.erb

和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

Answer 1

您需要确保group与post相关联，您可以仅使用try呈现纯内容（因此它不会呈现任何内容，但不会提升例外）：

<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%>

Account :: Posts #index中的NoMethodError

1 个答案: