Fallbacks

When working with variations of languages, like en-US or en-GB, it's useful for one locale set to fall back to another one to avoid duplication between your locales sets.

Fallback rules

Fallback rules are configured using the Rosetta::FallbackRules annotation:

@[Rosetta::AvailableLocales("en-GB", "en-US", :nl)]
@[Rosetta::FallbackRules({
  "en-GB": "en-US",
})]

In the example above, en-US is treated as the main locale set for English, which should be complete. The en-GB set only needs to include the translations deviating from en-US.

Chaining fallbacks

Fallbacks may also be chained:

@[Rosetta::AvailableLocales("en-GB", "en-US", :en, :nl)]
@[Rosetta::FallbackRules({
  "en-US": "en"
  "en-GB": "en-US",
})]

The callback chain will now be en-GB -> en-US -> en.

Info

It's important to note that fallback rules are applied sequentially. To be able to fall back to a set, it must be "complete". That is why, in the example above, en-US is falling back on en first, before en-GB can fall back on en-US.