zulip/docs/translating.md

Translating Zulip

Zulip has full support for unicode, so you can already use your preferred language everywhere in Zulip.

To make Zulip even better for users around the world, the Zulip UI is being translated into a number of major languages, including Spanish, German, French, Chinese, Russian, and Japanese, with varying levels of progress. If you speak a language other than English, your help with translating Zulip would be greatly appreciated!

If you're interested in contributing translations to Zulip, join the Zulip project on Transifex and ask to join any languages you'd like to contribute to (or add new ones). Transifex's notification system sometimes fails to notify the maintainers when you ask to join a project, so please send a quick email to zulip-core@googlegroups.com when you request to join the project or add a language so that we can be sure to accept your request to contribute.

Translation Tags

All user-facing text in the Zulip UI should be generated by a HTML template so that it can be translated.

Zulip uses two types of templates: backend templates (powered by the Jinja2 template engine, though the original Django template engine is still supported) and frontend templates (powered by Handlebars). At present, the frontend templates don't support translation (though we're working on fixing this!), so the rest of this discussion will be about the backend templates.

To mark a string for translation in the Jinja2 and Django template engines, you can use the _() function in the templates like this:

{{ _("English text") }}

If a string contains both a literal string component and variables, you can use a block translation, which makes use of placeholders to help translators to translated an entire sentence. To translate a block, Jinja2 uses the trans tag while Django uses the blocktrans tag. So rather than writing something ugly and confusing for translators like this:

# Don't do this!
{{ _("This string will have") }} {{ value }} {{ _("inside") }}

You can instead use:

# Jinja2 style
{% trans %}This string will have {{ value }} inside.{% endtrans %}
# Django style
{% blocktrans %}This string will have {{ value }} inside.{% endblocktrans %}

Zulip expects all the error messages to be translatable. To ensure this, the error message passed to json_error and JsonableError should always be a literal string enclosed by _() function, e.g:

json_error(_('English Text'))
JsonableError(_('English Text'))

To ensure we always internationalize our JSON errors messages, the Zulip linter (tools/lint-all) checks for correct usage.

Frontend Translations

The first step in translating the frontend is to create the translation files using python manage makemessages. This command will create translation files under static/locale, the location can be changed by passing an argument to the command, however make sure that the location is publicly accessible since these files are loaded through XHR in the frontend which will only work with publicly accessible resources.

The second step is to upload the translatable strings to Transifex using tx push -s -a.

The final step is to get the translated files from Transifex using tx pull -a.

Testing Translations

First of all make sure that you have compiled the translation strings using python manage.py compilemessages.

Django figures out the effective language by going through the following steps:

1. It looks for the language code in the url.
2. It loooks for the LANGUGE_SESSION_KEY key in the current user's session.
3. It looks for the cookie named 'django_language'. You can set a different name through LANGUAGE_COOKIE_NAME setting.
4. It looks for the Accept-Language HTTP header in the HTTP request. Normally your browser will take care of this.

The easiest way to test translations is through the i18n urls e.g. if you have German translations available you can access the German version of a page by going to /de/path_to_page.

To test translations using other methods you will need an HTTP client library like requests, cURL or urllib. Here is a sample code to test Accept-Language header using requests:

import requests
headers = {"Accept-Language": "de"}
response = requests.get("http://localhost:9991/login/", headers=headers)
print(response.content)