Railscasts - Layouts and content

Mar 21, 2007

Layouts and content_for

If you want to change something in the layout on a per-template basis, content_for is your answer! This allows templates to specify view code that can be placed anywhere in a layout.

Tags: views

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<!-- projects/index.rhtml -->
<% content_for :head do %>
  <%= stylesheet_link_tag 'projects' %>
<% end %>

<!-- layouts/application.rhtml -->
<head>
  <title>Todo List</title>
  <%= stylesheet_link_tag 'application' %>
  <%= yield :head %>
</head>

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12 comments

1. Christopher Jun 19, 2007 at 07:22

Thank you. Thank you. Thank you.

2. rs Jun 26, 2007 at 08:41

I don't like this method because you get two <link ... type="text/css" /> items in your HTML source.
I really don't think that this is an appropriate behavior.

3. Ryan Bates Jun 26, 2007 at 13:53

@rs, that's a valid concern. However, I think it's acceptable if one page requires a lot of additional styling. No sense in putting all this styling in a global CSS file and requiring it on every other page. Also, if the users are coming from another page they will likely have the global "application.css" stylesheet cached.

4. Brian Jun 27, 2007 at 01:48

hi,

what is the meaning of yield and :head in => <%= yield :head %>

5. Ryan Bates Jun 27, 2007 at 08:03

The "yield" call in a layout will output the contents of the template. When supplying a parameter (:head in this case) it will output the contents of that content_for block. I explained this in the episode, sorry if it wasn't clear.

6. louis Jul 10, 2007 at 01:01

@rs and ryan,
it seems to me that having multiple <link.../> tags is like having multiple <script /> tags in the head. is there some rule that says multiple script tags are ok, but link tags for css should be in one file? eric meyer has 8 stylesheet links on his homepage (as of today). i think he knows what he's doing vis-a-vis css.

it's a fantastic little railscast, btw. these little tricks make dev so much easier and smarter. thanks for doing this! you're a mensch.

7. Syn Oct 23, 2007 at 10:28

You can have multiple link tags. This is even used in the W3C standards to have multiple stylesheets specified for different medias, or simply to allow choice of stylesheets. (In Firefox, this shows up in the View Menu -> Page Style sub-menu.)

8. kriom Mar 14, 2008 at 03:26

What is the best way and is there a best way to call a "content_for" between
<%=yield :mycontent %>
and
<%=@content_for_mycontent %>

9. Robert B. Apr 06, 2008 at 09:07

kriom, there shouldn't be any difference, since content_for_mycontent is only old style version for yield in Rails, as far as I am concerned.

10. kino May 23, 2008 at 01:55

However, the reader should be careful to observe that the things in themselves stand in need to, even as this relates to our experience, our sense perceptions.

11. Faktura vat Jun 15, 2008 at 00:32

Wonderfull cast!

12. Avishai Aug 01, 2008 at 19:12

Great tip; It's really useful for including JavaScript/CSS that you only need on specific pages of your app.

I've used this technique to load some extra jQuery files and CSS that I needed for a sortable list and autocomplete widget. Very cool.

Layouts and content_for

12 comments

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