Question

The following is my application layout file

  .container_12.clearfix
  = render :partial => 'shared/flashes'

  .grid_8
    = render :partial => 'shared/search'        
    = yield
  .grid_4
    = yield(:sidebar)

It has to grids, one for content and another for sidebar.
Now I’m creating a login page in which I don’t want to show my sidebar(just the single grid.
I can simply create new layout with the .grid_12 div as the single grid.

But this leaves me with 2 app layouts.
How can I make the same application layout conditional to yield sidebar?

If with sidebar, it would be same as above
else just a single .grid_12 like the one below

  .container_12.clearfix
  = render :partial => 'shared/flashes'      
  .grid_12
    = render :partial => 'shared/search'        
    = yield

Answer 1

You can check if a content for :sidebar exists and render the sidebar if true.
Rails 2.3.5 will have a content_for? method. In the meantime, you can use my Helperful Gem.

- if has_content?(:sidebar)
  .grid_8
    = render :partial => 'shared/search'        
    = yield
  .grid_4
    = yield(:sidebar)
- else
  .grid_12
  = render :partial => 'shared/search'        
  = yield

Otherwise, you can assume if :sidebar == false then no sidebar.

  def sidebar(enable = true, &block)
    if enable
      content_for :sidebar, &block
    else
      @fullpage = true
    end
  end

  def fullpage?
    !!@fullpage
  end

- if fullpage?
  .grid_12
  = render :partial => 'shared/search'        
  = yield
- else
  .grid_8
    = render :partial => 'shared/search'        
    = yield
  .grid_4
    = yield(:sidebar)

Update:

If you are using Rails 3.x, check answer to a similar question for correct solution. The solution above doesn’t work with Rails 3.