Question

I have a Query model:

class Query < ActiveRecord::Base
   belongs_to :test
end

which is related to a Test model:

class Test < ActiveRecord::Base
 has_one :query
end

I would like to display all of the queries in a list along with the Test description that they are associated to. I’ve put the following into my Query controller file for the index method:

Query.includes(:test).each do |query|
end

My questions are two-fold:

1. Is the above correct?

2. What code can I use in the “view” field of my my index.html.erb file in order to display the description of the test that is associated with the Query? If I write

   <td><%= query.test.description %></td>
   

I get the following error: “undefined method `description’ for nil:NilClass”

Thanks.

Answer 1

Your loop shouldn’t be inside your controller. Your Queries controller should just contain the following:

def index
  @queries = Query.includes(:test).all
end

and your queries/index view should contain the loop:

<table>
<% @queries.each do |query| %>
  <tr>
    <td><%= query.test.description %></td>
  </tr>
<% end %>
</table>

You should further refractor this by using partials and Rail’s built-in support for rendering collections:

app/views/queries/index.html.erb:

<table><%= render @queries %></table>

app/views/queries/_query.html.erb:

<tr><%= render query.test %></tr>

app/views/tests/_test.html.erb:

<td><%= test.description %></td>