issue introduced in Haml 6.1.3 with using fallback (or specific non-html) format alternative

[timdiggins]

If you define custom formats / mime types e.g.

Mime::Type.register "application/xls", :xls
Mime::Type.register_alias "text/html", :raw

and then define layouts and partials based on a generic/fallback format (views/layouts/application.{erb,haml} and e.g.views/things/_thing.{erb,haml}).

so you have files (taking the haml view)

app/views/layouts/
  application.haml
  application.html.haml

app/things/
  _thing.haml
  _thing.html.haml
  show.haml
  show.html.haml

then working with this in haml 5 or haml 6.0 - the selection is made as expected/same as erb (.raw and .xls choose the one without .html, whereas .html choose the one with .html), ie.

• app/things/show.haml
• app/things/_thing.haml
• app/layouts/application.haml

but when you move to haml 6.1 the selection is made as follows:

• app/things/show.html.haml
• app/things/_thing.haml
• app/layouts/application.html.haml

Screenshots

Expected .html

Expected .raw (erb, haml-5, haml-6.0, haml-6.1.2)

Got .raw (haml-6.1.3+)

reproduction repo

see https://github.com/timdiggins/haml-issue-1154

main branch is erb, separate branches for different haml versions

rails test:all

[timdiggins]

The workaround for this is to monkey-patch and revert the addition of default_format to Haml::RailsTemplate

require "haml/rails_template"

module Haml
  class RailsTemplate
    def default_format
      nil
    end
  end
end

https://github.com/timdiggins/haml-issue-1154/tree/workaround

[k0kubun]

Removed #default_format in v6.3.0.