Two Similar Partials, One Giving Error, Other Is Fine

Question

I have two partials, that are almost exactly the same, except one is a full view, and the other is a compact. They are both under 'projects' view, but one works correctly, and the other gives errors:

projects/_project.html.erb

<div class="pure-u-1-3">
<%= link_to project do %>
  <div class="project">
    <h4 class="red marginless"><%= truncate( project.title, length: 22, separator: ' ') %></h4>
    <p class="left marginless"><strong>By:</strong> <%= project.user.username %><br>
    <strong>Genres:</strong> <%= truncate( project.genre2, length: 25, separator: ' ') %><br><br>

    <strong>Description:</strong><br>
    <%= truncate( project.description, length: 60, separator: ' ') %><br>

    <strong>Needs:</strong><br>
    <%= truncate( project.looking_for, length: 60, separator: ' ') %></p>
  </div>
<% end %>

<% if @projects.size == 0 %>
 <em> no projects found with that criteria </em>
<% end %>
</div>

projects/_short.html.erb

<div class="pure-u-1-3">
<%= link_to project do %>
  <div class="project">
    <h4 class="red marginless"><%= truncate( project.title, length: 22, separator: ' ') %></h4>
    <p class="left marginless"><strong>By:</strong> <%= project.user.username %></p>
  </div>
<% end %>
</div>

Now, this is the part of the view using these partials:

dashboards/index.html.erb

<% if @projects.length > 0 %>
 <div class="pure-u-1" id="projects"><h3 class="red"><%= current_user.username %>'s Owned Projects</h3>
  <%= render :partial => 'projects/short', :collection => @projects %>
 </div>
<% end %>

When I have 'projects/project' it works perfectly, no issues. When I put 'projects/short' it gives me this error:

undefined local variable or method `project'

This error is given everywhere the word project is used on _short, unless I use @project, but then it gives me this error:

undefined method `title' for nil:NilClass (same for user)

I do not understand how the partials can be in the exact same spot, and used the exact same way, in the exact same spot, but one works and the other does not. Is there code I may have done in the past, that I am missing that makes this work?

score 1 · Accepted Answer · answered May 28 '14 at 04:26

You need to supply the as: :project option to the render partial call as:

<% if @projects.length > 0 %>
 <div class="pure-u-1" id="projects"><h3 class="red"><%= current_user.username %>'s Owned Projects</h3>
  <%= render :partial => 'projects/short', :collection => @projects, as: :project %>
 </div>
<% end %>

This will make project local variable available within the partial projects/short.

The reason you are getting the error is because (from the documentation on rendering collections within Using render):

When a partial is called with a pluralized collection, then the individual instances of the partial have access to the member of the collection being rendered via a variable named after the partial.

Instead of my comment, I put an 'answer' below, since it made the code easier to read... — Azketta, May 28 '14 at 04:58

score 0 · Answer 2 · answered May 28 '14 at 04:58

Okay, so before I actually saw the above answer, I was still sorting through documentation, and from my best understanding, I actually just changed everything that said project to compact now like:

<h4 class="red marginless"><%= truncate( compact.title, length: 22, separator: ' ') %></h4>
<p class="left marginless"><strong>By:</strong> <%= compact.user.username %></p>

Is this the 'wrong' way to do it? It seems to be working perfectly now...

Two Similar Partials, One Giving Error, Other Is Fine

2 Answers2