Additional stimulus controller "lookup" paths in importmap_helper.rb

[forsbergplustwo]

Firstly, thanks for this library.. it feels like the future! It's also been a great intro to ESM and how that works.

We're running into an issue using this together with a Rails engine, because the importmap_helper.rbfile is hardcoded to look in the Rails.root folder only, when resolving the paths for stimulus controllers.

  def importmap_list_from(*paths)
    Array(paths).flat_map do |path|
      if (absolute_path = Rails.root.join(path)).exist?
        find_javascript_files_in_tree(absolute_path).collect do |filename|
          module_filename = filename.relative_path_from(absolute_path)
          module_name     = importmap_module_name_from(module_filename)
          module_path     = asset_path(absolute_path.basename.join(module_filename))

          %("#{module_name}": "#{module_path}")
        end
      end
    end.compact.join(",\n")
  end

stimulus-rails/lib/stimulus/importmap_helper.rb

Line 8 in 13383ac

if (absolute_path = Rails.root.join(path)).exist?

We can work around this by manually adding our engine's stimulus controllers to the importmap.json file like so:

{
  "imports": {
    "turbo": "<%= asset_path "turbo" %>",
    <%= importmap_list_with_stimulus_from "app/assets/javascripts/controllers", "app/assets/javascripts/libraries" %>,
    "slideshow_controller": "<%= asset_path "slideshow_controller" %>"
  }
}

where slideshow_controller resides under the engine.

It would be great if we could specify which root paths to use in this helper, so we can include AppKit::Engine.root in the helper path, for example and have it work automatically.

Would this be a welcome option if we gave it a go for a PR? A bit unsure how best to do it, while also keeping the interface simple like it is now: importmap_list_from(*paths) so open to ideas and suggestions.

[dhh]

I think we could make this work by having it accept both relative and absolute paths. Relative would work as now, going off Rails.root, but absolute (starting with /) would allow for engines 👍

[forsbergplustwo]

Thanks, that's a great suggestion. I'll give it a shot 😎

[forsbergplustwo]

PR #39 created to add support for this.

The change could have been just taking this line:

      if (absolute_path = Rails.root.join(path)).exist?

And making it:

     if (absolute_path = Rails.root.join(Pathname.new(path))).exist?

But it felt like too much magic and hard to understand. Hence I've added a clearer method. Happy to change if you feel example above is ok.