content_for(name, content = nil, &block) public

Calling content_for stores the block of markup for later use. Subsequently, you can make calls to it by name with yield in another template or in the layout.

Example: 

  <% content_for("header") do %>
    alert('hello world')
  <% end %>

You can use yield :header anywhere in your templates. 

  <%= yield :header %>

NOTE: Beware that content_for is ignored in caches. So you shouldn’t use it for elements that are going to be fragment cached.

The deprecated way of accessing a content_for block was to use a instance variable named @@content_for_#{name_of_the_content_block}@. So <%= content_for('footer') %> would be avaiable as <%= @content_for_footer %>. The preferred notation now is <%= yield :footer %>.

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February 12, 2010
1 thank

Check content_for content

There is a content_for? method in Rails wherewith you can check the content. http://github.com/rails/rails/commit/9cb8c812f2a23ab5653a7888740a014a02c97c18#diff-1

But it’s not in the last stable version (2.3.5) http://github.com/rails/rails/blob/v2.3.5/actionpack/lib/action_view/helpers/capture_helper.rb

November 26, 2009
0 thanks

How to check if a Yield has content?

How do I do this without actually calling the yield? 

  - if yield :footer
    = yield :footer
  - else
    = render "layouts/footer_big"

(Note: HAML Syntax) Thanks.

November 30, 2009 - (>= v2.3.4)
0 thanks

Clearing out previous values from content_for

By default, content_for :thing appends whatever you put in your block to the previous value of :thing. In some cases, you’d like to clear out :thing rather than append to it.

I just posted a way to do this on my blog: http://stevechanin.blogspot.com/2009/11/clearing-out-content-in-contentfor.html

I add a new method set_content_for that works just like content_for, but clears out :thing first. It doesn’t touch how content_for works, so it shouldn’t cause any problems anywhere else in your app.