Proper SCSS Asset Structure in Rails

Question

So, I have an app/assets/stylesheets/ directory structure that looks something like this:

   |-dialogs
   |-mixins
   |---buttons
   |---gradients
   |---vendor_support
   |---widgets
   |-pages
   |-structure
   |-ui_elements

In each directory, there are multiple sass partials (usually *.css.scss, but one or two *.css.scss.erb).

I might be assuming a lot, but rails SHOULD automatically compile all the files in those directories because of *= require_tree . in application.css, right?

I recently have tried restructuring these files by removing all color variables and placing them in a file in the root app/assets/stylesheets folder (_colors.css.scss). I then created a file in the root app/assets/stylesheets folder called master.css.scss which looks like this:

// Color Palette 
@import "colors";

// Mixins
@import "mixins/buttons/standard_button";
@import "mixins/gradients/table_header_fade";
@import "mixins/vendor_support/rounded_corners";
@import "mixins/vendor_support/rounded_corners_top";
@import "mixins/vendor_support/box_shadow";
@import "mixins/vendor_support/opacity";

I don't really understand how rails handles the order of asset compilation, but it's obviously not in my favor. It appears none of the files realize they have any variables or mixins being imported, and so it throws errors and I can't compile.

Undefined variable: "$dialog_divider_color".
  (in /home/blah/app/assets/stylesheets/dialogs/dialog.css.scss.erb)

Undefined mixin 'rounded_corners'.
  (in /home/blah/app/assets/stylesheets/widgets.css.scss)

The variable $dialog_divider_color is clearly defined in _colors.css.scss, and _master.css.scss is importing colors and all my mixins. But apparently rails didn't get that memo.

Is there some way I can fix these errors, or will I need to resort to putting all my variable definitions back into each individual file, as well as all the mixin imports?

Unfortunately, this guy doesn't seem to think it's possible, but I'm hoping he's wrong. Any thoughts are greatly appreciated.

Answer 1

The problem with CSS is, you do not want to automatically add all files. The order of which your sheets are loaded and processed by the browser is essential. So you will always end up explicitly importing all your css.

As an example, lets say you have a normalize.css sheet, to get a default look instead of all the horrible different browser implementations. This should be the first file the browser loads. If you just randomly include this sheet somewhere in your css imports, it will then not only override the browser default styles, but also any styles defined in all css files that were loaded before it. This goes the same for variables and mixins.

After seeing a presentation by Roy Tomeij at Euruko2012 I decided for the following approach if you have a lot of CSS to manage.

I generally use this approach:

1. Rename all existing .css files to .scss
2. Remove all contents from application.scss

Start adding @import directives to application.scss.

If you are using twitters bootstrap and a few css sheets of your own, you have to import bootstrap first, because it has a sheet to reset styles. So you add @import "bootstrap/bootstrap.scss"; to your application.scss.

The bootstrap.scss file looks like:

// CSS Reset
@import "reset.scss";

// Core
@import "variables.scss";
@import "mixins.scss";

// Grid system and page structure
@import "scaffolding.scss";

// Styled patterns and elements
@import "type.scss";
@import "forms.scss";
@import "tables.scss";
@import "patterns.scss";

And your application.scss file look like:

@import "bootstrap/bootstrap.scss";

Because of the order of the imports, you can now use the variables, loaded with @import "variables.scss"; in any other .scss file imported after it. So they can be used in type.scss in the bootstrap folder but also in my_model.css.scss.

After this create a folder named partials or modules. This will be the place of most of the other files. You can just add the import to the application.scss file so it will look like:

@import "bootstrap/bootstrap.scss";
@import "partials/*";

Now if you make a bit of css to style an article on your homepage. Just create partials/_article.scss and it will be added to the compiled application.css. Because of the import order you can also use any bootstrap mixins and variables in your own scss files.

The only drawback of this method I found so far is, sometimes you have to force a recompile of the partial/*.scss files because rails wont always do it for you.