Question

I have situation where I generate stylesheets based on information in the database. This means I have a views/users/show.css.erb which contains code like:

a {
  color: <%= @user.favorite_color %>;
}

Fair enough, works perfectly with a respond_to { |f| f.css } in my controller. However now I would like to use some of SASS’s sassy functions like lighten, darken etc. in my CSS, so I would like to have SASS parse my view. However I cannot figure out how to register SASS as a template handler in my views without too much ugly hacks. I just don’t get how it works. Has anyone ever tried this?

I have tried including SASS’s Functions module but to no avail.

Answer 1

I was planning of doing the same for dynamic user themes some time ago. Back then, I found a mailing list answer to a similar question to yours, by Nathan Weizenbaum (author of SASS) which got me back on the straight and narrow:

On Mar 18, 11:46 am, Nathan Weizenbaum wrote:

There’s a reason Sass doesn’t allow dynamic access to Rails code – see
the Sass section ofhttp://haml.hamptoncatlin.com/docs/rdoc/files/FAQ.htmlfor
a brief discussion. Sass is also fairly slow, since it’s only compiled once,
so this is probably far too slow for a production environment.

The link is not working anymore, but the SASS FAQ has only one section called Can I use a variable from my controller in my Sass file? which answer the dynamic question:

If you really, really need to compile Sass on each request, first make sure you have adequate caching set up. Then you can use Sass::Engine to render the code, using the :custom option to pass in data that can be accessed from your Sass functions.

So in general, SASS is not designed for dynamic css generation on each request. Rather it is intended to be used as a pre compilation solution to generate static css files.