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Transdifflation travis-ci Dependency Status Code Climate Gem Version

What is Transdifflation? Transdifflation is a portmanteau of 'Translation' and 'Diff'. It helps you to manage the translation of Rails i18n strings that appear in your application and the Ruby Gems it includes.

It compares two .yml locale files, one in your source code (the target) and one in others' (gems, other projects) source code (the source) and generates a beside-file with the keys you haven't translated yet. Then you can merge it. It is designed to detect changes between versions. For now, the target file cannot be renamed, and it is generated in 'config/locales/' + to_locale (param in task). Names are inferred by the task params.

Also, it has three new rake tasks to provide information to you about missing translations between two locales, and continuous integration support.

It never changes your source files (unless they don't yet exist, in which case they are created for you).


Add this line to your application's Gemfile:

gem 'transdifflation'

And then execute:

$ bundle

Or install it yourself as:

$ gem install transdifflation


How to configure your Rake tasks

It needs a config file (transdifflation.yml) placed on your host root, or in 'config'. If not exists, a rake task is set up to generate it: rake transdifflation:config. Config file looks like:

  task_name1: {
    desc: 'Get diff translation from file config/locales/en.yml gem gem_name',
    type: gem,
    params: {
      gem_name: 'gem_name',
      path_in_gem: 'config/locales/en.yml',
      from_locale: 'en',
      to_locale: 'es'
  task_name2: {
    desc: 'Get diff translation from file config/locales/en.yml file in file_path',
    type: file,
    params: {
      tag_name: 'tag_for_file',
      file_path_from_rails_root: '../another_project/config/locales/en.yml',
      from_locale: 'en',
      to_locale: 'fr'
    - task_name1
    - task_name2

  - /path_one
  - gem_path

These nodes generates rake tasks. There are two types of tasks:

  • type gem: When it rans, it checks where the gem 'gem_name' is installed, and looks inside the gem for the file located in 'path_in_gem'. It uses from_locale and to_locale to translate names and keys inside yaml.

  • type file: When it rans, it looks for the file in 'file_path_from_rails_root' is installed. It uses from_locale and to_locale to translate names and keys inside yaml. Tag_name is used to name target file in our host.

Also, you can create grouped tasks in a node called 'grouped_taks'. Task transdifflation:all is automatically generated.

Execute rake -T to determine sucess of config file. Your tasks should appear there, under namespace `transdifflation:

'Out of the box' rake tasks

There are two new tasks in the town:

  • rake transdifflation:lost_in_translation[from_locale,to_locale]
  • rake transdifflation:lost_in_translation_ci[from_locale,to_locale]
  • rake transdifflation:coverage[from_locale,to_locale]

These tasks are intended to be used to know what keys are missing between two locales. rake transdifflation:lost_in_translation[from_locale,to_locale] creates a file in [Rails.root]/config/locales/[from_locale]/missing_translations.yml.diff(on YAML format), that you can use as a template to fulfill your translation.

rake transdifflation:lost_in_translation_ci[from_locale,to_locale] doesn't create a file, it just fails if missing translations needed, so you can use it in a continuous integration environment, if you want to test that your translations are always completed between your third party gems' new versions, or other vendor's project new releases, or stuff like that... You can configure ignore_paths to ignore whatever gem you don't what to check

rake transdifflation:coverage[from_locale,to_locale] gives you information and statistics of translations. You can configure ignore_paths too.


  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Added some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request