Question

I’m migrating a Website from Rails 2 (latest) to Rails 3 (beta2).
Testing with Ruby 1.9.1p378 and Ruby 1.9.2dev (2010-04-05 trunk 27225)

Stuck in a situation, i don’t know which part will work well. Suspect yield is the problem, but don’t know exactly.

In my Layout Files I use the following technique quite often:

app/views/layouts/application.html.erb:

<%= yield(:sidebar) || render('shared/sidebar') %>

---

For Example the partial look like:

app/views/shared/_sidebar.html.erb:

<p>Default sidebar Content. Bla Bla</p>

---

Now it is time for the key part!
In any view, I want to create a content_for block (optional). This can contain a pice of HTML etc. example below. If this block is set, the pice HTML inside should render in application.html.erb.
If not, Rails should render the Partial at shared/_sidebar.html.erb on the right hand side.

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

<% content_for :sidebar do %>
    <strong>You have to read REWORK, a book from 37signals!</strong>
<% end %>

---

So you’ve got the idea. Hopefully. This technique worked well in any Rails 2.x Application.
Now, in Rails 3 (beta2) only the yield Part is working.

|| render('shared/sidebar')

The or side will not process by rails or maybe ruby.

Thanks for input and time!

Answer 1

Ryan Bates from railscasts.com shows in Episode #227 – Upgrading to Rails 3 Part 3 a solution with content_for?() (video playback at 2:45 Min)

I think, that’s the way we should use it:

content_for?(:sidebar) ? yield(:sidebar) : render("shared/sidebar")