Adding translations for a new language

To add support for a new language, you need to perform the following steps:

  1. Create a new language file in folder i18n, e.g. by copying the english.yml file.
  2. In the newly created <new language>.yml, adapt the first two lines: _id should conform to the ISO 639 language code, _name to the localized language name.
  3. In lib/common/util/config.js, add the import of the new language file at the mark // Add additional language files here. Mind to add an // $FlowFixMe hint before the new line to make the linter happy
  4. Translate all messages in the <new language>.yml file. Note, that names surrounded by percent characters (%) denote parameters and must not be translated.
  5. Add a new line to the CHANGELOG, e.g. Add support for <new language>.
  6. Before commiting, run yarn run lint-messages or yarn run test.

Internationalizing components

To internationalize components not yet translated, perform the following steps:

  • For components not yet translated:
    • import getComponentMessages from common/util.config.
    • assign getComponentMessages('') to a component properties messages
    • extract not yet translated messages from component files to i18n/english.yml and replace their original text by this.messages('').
    • in case the original message contains dynamic parts, you should create placeholders (e.g. %placeholder%, and replacing that string with the intended value after calling this.messages('<key>')). Note that numeric parameters should be converted to strings.
  • When done, add the new message keys to the existing translation files, e.g. using yq, like e.g. yq merge i18n/german.yml i18n/english.yml | sponge i18n/german.yml. Note: Besides merging the missing keys, yq has some reformatting/reordering side effects, i.e. messages surrounded by brackets need to be quoted, otherwise they are converted to nested arrays.
  • Periodically, and especially before commiting, run yarn run lint-messages or yarn run test to be sure all tests are still running.

Note: console log messages are not intended to be localized

Open issues

There are a few sections, which are not yet prepared for i18n and will not adapt to the user's locale: * The alerts module (lib/alerts/**) is not yet fully internationalized. * A couple of messages (i.e. job names and status) are generated server-side and are not internationalized yet. * Time and date formatting performed by the moment javascript lib are not locale aware. * Some messages from the react-bootstrap table component, e.g. Showing row x-y of z. * GTFS-related field names and descriptions defined in GTFS.yml.