Sprockets register_engine deprecated

[SidOfc]

Hello there!

I'm using the skim gem to convert hamljs templates to slim using the .jst.skim extension. It works perfectly but Sprockets as of version 3.7.0 deprecated the register_engine call in favor of a different approach using register_mime_type and either register_compressor or register_transformer.

• An explanation on register_mime_type and register_transformer
• An example of how the class passed in register_transformer should look

It shows that they added a deprecation notice in the 3.7.0 section in the release notes

This is the exact error I'm getting:

DEPRECATION WARNING: Sprockets method `register_engine` is deprecated.
Please register a mime type using `register_mime_type` then
use `register_compressor` or `register_transformer`.
https://github.com/rails/sprockets/blob/master/guides/extending_sprockets.md#supporting-all-versions-of-sprockets-in-processors
 (called from <top (required)> at /Users/myusername/.rvm/gems/ruby-2.3.0/gems/skim-0.10.0/lib/skim/sprockets.rb:3)

From what I can find, there is no simple way to get around this deprecation warning due to the fact that version 3.7.0 deprecates the functionality but still requires you to use it :|

I would write something along these lines to fix the registering issue, however the Skim::Template class cannot handle Sprockets 4 yet (which is still in beta at the time of writing). Either way it might give you some inspiration!

if Sprockets.respond_to?(:register_engine)
  args = ['.skim', Skim::Template]
  if Sprockets::VERSION.start_with? '3'
    args << {silence_deprecation: true, mime_type: 'text/skim'}
  end

  Sprockets.register_engine *args
else
  Sprockets.register_mime_type 'text/skim', extensions: ['.skim', '.jst.skim']
  Sprockets.register_transformer 'text/skim', 'application/javascript', Skim::Template
end

Replicating this issue should be simple.

In a fresh Rails (5, using sprockets >= 3.7.0) app,

Gemfile

gem 'skim'
gem 'sprockets', '>= 3.7.0'

Run the bundle or bundle install command
Restart rails server (ctrl+c to stop rails s to start)

The message should appear when starting the server, if not try creating a template

[mohsintahir]

Any fix to this?

[SidOfc]

@mohsintahir the last commit was on 8th of July 2016, it's been stale for quite a while. Your best chance would be to look at forks to see if anyone continued maintenance.

[mohsintahir]

Got it. Thanks!

[SidOfc]

It seems that this has been resolved in a118ab7, closing.