simple rails helper gives "NoMethodError"

Question

helpers/subcategories_helper.rb:

module SubcategoriesHelper
  def has_topic_headings?
    self.topic_headings
  end
end

categories/show.html.erb contains

          <% @category.subcategories.each do |subcategory| %>
            <li>
              <h6>
                <%if subcategory.has_topic_headings? %>
                  <%= link_to subcategory.name, subcategory, data: :has_topic_headings %>
                <% else %>
                  <%= link_to subcategory.name, subcategory %>
                <% end %>  
              </h6>
              <hr>
            </li>
          <% end %>

The page returns

undefined method `has_topic_headings?' for #<Subcategory:0xa68748c>

Please note that the view page belongs to the Category, not the Subcategory.

Answer 1

You are trying to call it on model which is why it is not called on when helper is included. Helpers are there for views and sometimes for controllers.

Answer 2

Here is your method :

<%= link_to subcategory.name, subcategory, data: :has_topic_headings %>

Edit: Sorry for misunderstanding. the error is in your data which you are passing in your link:

data: :has_topic_headings

rails is asking for above method, not for has_topic_headings?

Edit: Yes, as @techvineet said, you cannot call a helper method on a subcategory object. you should write method in your subcategory model:

 def has_topic_headings?
    return true if self.topic_headings
 end

Or you can do this in your helper class:

def has_topic_headings(subcategory)
   return true if subcategory.topic_headings
end

and in your form, call it like this:

<%if has_topic_headings(subcategory) %>
  <%= link_to subcategory.name, subcategory, data: :has_topic_headings %>
<% else %>
  <%= link_to subcategory.name, subcategory %>
<% end %>  

Hope it will help.Thanks