Question

I am just starting on rails and found a problem which I can’t solve. I am creating a simple app with two models (awards and students). :award has_one :student and :student belongs_to :award

I was told that in app/views/awards/ in show.html.erb, replace:

<%= @award.student_id %>

with:

<%= @award.student.given_name %> <%= @award.student.family_name %>

and in index.html.erb, replace:

<%= award.student_id %>

with:

<%= award.student.given_name %> <%= award.student.family_name %>

after this the localhost:3000/students is working fine but localhost:3000/awards is not working and giving following error :-

**NoMethodError in Awards#index**

Showing /home/redblink/rbtest/students/app/views/awards/index.html.erb where line #17 raised:

undefined method `given_name' for nil:NilClass

Extracted source (around line #17):

14:   <tr>
15:     <td><%= award.name %></td>
16:     <td><%= award.year %></td>
17:     <td><%= award.student.given_name %> <%= award.student.family_name %></td>
18:     <td><%= link_to 'Show', award %></td>
19:     <td><%= link_to 'Edit', edit_award_path(award) %></td>
20:     <td><%= link_to 'Destroy', award, method: :delete, data: { confirm: 'Are you sure?' } %></td>

please reply asap with the solution…..

Answer 1

The problem is that there is one of the awards record whose corresponding students record is not present so its returning nil and u can call given_name on nil.

So you can handle it as:

Write following:

<%= award.student ? award.student.given_name : '' %> <%= award.student ? award.student.family_name : '' %>

instead of

<%= award.student.given_name %> <%= award.student.family_name %>