NoMethodError在帳戶::帖子＃index

我正在做Ruby101教程，但出錯了。NoMethodError在帳戶::帖子＃index

軌道日誌：

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>

應用程序/視圖/帳號/職位/ index.html.erb：16：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' 渲染/home/zedong/.rvm/gems/ruby -2.3.1/gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescue/template_error.html.erb in rescue/layout Rendering /home/zedong/.rvm/gems/ruby-2.3.1/ gems/actionpack-5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_source.html.erb Rendered /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） Rendering /home/zedong/.rvm/gems/ruby-2.3.1/gems/actionpack -5.0.0.1/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb Rendered /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） Rendering /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 呈現/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 ）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內的救援/ layo UT（21.5ms）

而且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

的post.rb：

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

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

因爲我在做這個教程的第二次，所以我比較它與第一次的代碼。我試圖一個接一個地複製文件來發現問題，但它不能工作。順便說一下，當我想實現eidt和刪除按鈕時，出現了一些錯誤。

項目在這裏：github

來源

2016-11-05 張澤棟

這只是你在那個特定時間沒有與該帖子相關的羣組。如果你想忽略它，你可以使用'post.group.try（：title）'。如果組爲'nil'，則不會引發錯誤。 –

你需要確保有一個與post相關的group，您可以使用try只爲呈現純內容（所以它呈現什麼都沒有，但不會引發異常）：

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

而且if控制流有條件地呈現鏈接：

<% 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%>

來源

2016-11-05 04:05:17 potashin

NoMethodError在帳戶::帖子＃index

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