🎩 What? Why?

We're working on adding a machine-translation system for Decidim. This comes from:

https://meta.decidim.org/processes/roadmap/f/122/proposals/15238

This PR will serve as a base branch for all related changes, so that we don't accidentally release the feature half way.

Implementation

The whole system will lay behind two config options:

1. Installation-wise (Decidim.config.enable_machine_translations), disabled by default
2. Organization setting, disabled by default, only visible if the installation one is enabled.

We'll create Decidim::TranslatedField, a new model that will hold all machine translations. This is the same approach the globalize gem does. By separating these translations we have a way to differentiate machine translations from human translations.

This is the process:

1. Someone creates or updates a translatable resource.
2. We gather this resource, check if the fields need to be translated, and for each that does we create a new Decidim::TranslatedField in a "pending" state. This means we've scheduled a translation request but it's not finished yet.
3. Using ActiveRecord hooks, we gather the translatable resource and send it to a job if the machine translation is enabled. This job will send the translation request for that field an expect nothing. Translation requests usually happen in an asynchronous way, for what we've gathered. We'll send 1 job per language that needs translation.
4. We'll build a dummy translator that will serve as an example for other implementators. This dummy translator will only prepend the locale name to the field value, and update the Decidim::TranslatedField with it.
5. We'll replace all translated_attribute(model.field) calls, because with the current method we can't get to the DB because we only receive the field value. We'll create a new translated(model, :field) that will behave similarly to the current one, but if there's no human translation available then we'll delegate the search to the Decidim::TranslatedField table.
6. We'll add a custom Rubocop rule that will run together with the linter CI step that will ensure we don't use the old translated_attribute(model.field) method, and help us automfix this change. We'll also deprecate the old method, just in case.

With this system, we expect developers to be able to implement bridges to Google Translate, DeepL, Bing or similar services.

📌 Related Issues

• https://meta.decidim.org/processes/roadmap/f/122/proposals/15238

📋 Subtasks

See related PRs.

📷 Screenshots (optional)