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https://github.com/metaskills/less-rails

:-1: :train: Less.js For Rails
https://github.com/metaskills/less-rails

Last synced: about 19 hours ago
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:-1: :train: Less.js For Rails

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# The dynamic stylesheet language for the Rails 5+ asset pipeline.



This gem provides integration for Rails projects using the Less stylesheet language in the asset pipeline.



[![Build Status](https://secure.travis-ci.org/metaskills/minitest-spec-rails.svg)](http://travis-ci.org/metaskills/less-rails)



## Installing



Just bundle up less-rails in your Gemfile. This will pull in less as a runtime dependency too.



```ruby

gem 'less-rails', '~> 4.0.0'

```



But be warned, less.rb relies on a JavaScript runtime gem too. Just like ExecJS, it will look for a gem that is appropriate to your system. Typically, this means you will need one of the following.



```ruby

gem 'therubyracer' # Ruby

gem 'therubyrhino' # JRuby

```



## Configuration



This gem was made for other gems to properly hook into one place to provide paths to the Less::Parser. For example, the less-rails-bootstrap project at http://github.com/metaskills/less-rails-bootstrap and each project should do the path configuration for you. If you need to, you can configure less-rails with additional paths. These paths have higher priority than those from your applications assets load paths.



```ruby

MyProject::Application.configure do

  config.less.paths << "#{Rails.root}/lib/less/protractor/stylesheets"

  config.less.compress = true

end

```



#### About Compression



If `config.assets.compress` is set to true, we will set the `config.less.compress` to true as well. Less has real basic compression and it is recommended that you set the rails `config.assets.css_compressor` to something more stronger like `:yui` in your `config/environments/production.rb` file. Note, this requires the [yui-compressor](https://rubygems.org/gems/yui-compressor) gem but does an excellent job of compressing assets.



## Import Hooks



Any `@import` to a `.less` file will automatically declare that file as a sprockets dependency to the file importing it. This means that you can edit imported framework files and see changes reflected in the parent during development. So this:



```css

@import "frameworks/bootstrap/mixins";



#leftnav { .border-radius(5px); }

```



Will end up acting as if you had done this below:



```css

/*

 *= depend_on "frameworks/bootstrap/mixins.less"

*/



@import "frameworks/bootstrap/mixins";



#leftnav { .border-radius(5px); }

```



## Passing parameters to less.rb



You can pass any parameters that the [`less.rb`](https://github.com/cowboyd/less.rb) gem (which `less-rails` is based upon) supports by modifying `Rails.application.config.less.raw`.

For example, `less.rb` uses [lessc --relative-urls](http://lesscss.org/usage/#command-line-usage-relative-urls) by default. This means that `url('../ralative/paths.png')` for `@import`ed files will be modified according to `.less` file location. To return back to default `lessc` behavior, add these lines to `config/initializers/assets.rb`:



```ruby

Rails.application.config.less.raw.relativeUrls = false

```



For more parameters supported by `less.rb`, please consult [less.rb gem](https://github.com/cowboyd/less.rb/blob/master/lib/less/defaults.rb).



## Helpers



When referencing assets use the following helpers in LESS.



```css

asset-path(@relative-asset-path)  /* Returns a string to the asset. */

asset-path("rails.png")           /* Becomes: "/assets/rails.png" */



asset-url(@relative-asset-path)   /* Returns url reference to the asset. */

asset-url("rails.png")            /* Becomes: url(/assets/rails.png) */

```



As a convenience, for each of the following asset classes there are corresponding `-path` and `-url` helpers image, font, video, audio, javascript and stylesheet. The following examples only show the `-url` variants since you get the idea of the `-path` ones above.



```css

image-url("rails.png")            /* Becomes: url(/assets/rails.png) */

font-url("rails.ttf")             /* Becomes: url(/assets/rails.ttf) */

video-url("rails.mp4")            /* Becomes: url(/videos/rails.mp4) */

audio-url("rails.mp3")            /* Becomes: url(/audios/rails.mp3) */

javascript-url("rails.js")        /* Becomes: url(/assets/rails.js) */

stylesheet-url("rails.css")       /* Becomes: url(/assets/rails.css) */

```



Lastly, we provide a data url method for base64 encoding assets.



```css

asset-data-url("rails.png")       /* Becomes: url(data:image/png;base64,iVBORw0K...) */

```



Please note that these helpers are only available server-side, and something like ERB templates should be used if client-side rendering is desired.



## Generators



Installation of the gem will set your applications stylesheet engine to use Less. It is possible to have many gems that set the stylesheet engine, for instance the sass-rails and/or stylus gems. In this case, you can resolve the ambiguity by setting the stylesheet engine in your `config/application.rb` file like so. Doing so would mean all generated assets will be in the a fresh `css.less` template.



```ruby

config.app_generators.stylesheet_engine :less

```



We have generators for both assets and scaffold in the `less` namespace. For instance the following would generate a blank `app/assets/stylesheets/posts.css.less` template.



```

$ rails generate less:assets posts

```



We also have a generator for rails scaffold CSS. Just like the Sass gem, we simply parse the scaffold.css in the default rails generator and save it as a scaffolds.css.less file. This is done automatically during other scaffold generator actions.



## Contributing



This gem is fully tested from Rails 5.0 to Rails 6.0. We run our tests on [Travis CI](http://travis-ci.org/metaskills/less-rails) for officialy supported Rubies If you detect a problem, open up a github issue or fork the repo and help out. After you fork or clone the repository, the following commands will get you up and running on the test suite. 



```shell

$ bundle

$ bundle exec appraisal install

$ bundle exec appraisal rake

```



We use the [appraisal](https://github.com/thoughtbot/appraisal) gem from Thoughtbot to help us generate the individual gemfiles for each Rails version and to run the tests locally against each generated Gemfile. The `rake appraisal test` command actually runs our test suite against all Rails versions in our `Appraisal` file. If you want to run the tests for a specific Rails version, use `rake -T` for a list. For example, the following command will run the tests for Rails 5.0 only.



```shell

$ bundle exec rake appraisal:rails50 test

```



Our current build status is:

[![Build Status](https://secure.travis-ci.org/metaskills/minitest-spec-rails.png)](http://travis-ci.org/metaskills/less-rails)



## License



Less::Rails is Copyright (c) 2011-2013 Ken Collins,  and is distributed under the MIT license.