NoMethodError undefined method `name' for nil:NilClass

ruby-on-rails, ruby-on-rails-4

Solution

Your `@posts` instance variable contains instances of `Post` that, for whatever reason, aren't associated to a parent `Category`. You can avoid the `NilClass` error by checking whether each `Post` has an associated `Category` before printing the category's name:

<%= post.category.name if post.category %>

Alternatively, since the existence of a `Post` that isn't associated with a `Category` is probably undesirable, you may want to wrap the entire block in a conditional that checks for a `Category`:

<% @posts.each do |post| %>
  <% if post.category %> # Check for parent category
    # Remaining code
  <% end %>
<% end %>

Problem

I have two models post and category. I'm trying to show the category name for each post in both my index and show view of post. I'm using table join. But the problem is though in my show view the category is showing properly, but its giving a NoMethodError: undefined method `name' for nil:NilClass in the index view. I can't figure out why it's showing in my show view but not in the index view. index.html.erb ``` <% @posts.each do |post| %> <h2><%= link_to post.title, post %></h2> <p>বিভাগঃ <%= post.category.name %></p> <p><%= post.body %></p> <%= link_to 'দেখুন', post, class: "button tiny" %>&nbsp; <%= link_to 'সম্পাদনা', edit_post_path(post), class: "button tiny" %> <% end %> ``` show.html.erb ``` <h2><%= link_to @post.title, @post %></h2> <h5>বিভাগঃ <%= @post.category.name %></h5> <p><%= @post.body %></p> ``` post.rb ``` class Post < ActiveRecord::Base validates_presence_of :title, :body, :category has_many :comments belongs_to :category end ``` category.rb ``` class Category < ActiveRecord::Base has_many :posts end ```

Original source