Language Resolution
Here, let's take a look into how language in Frappe is resolved, and how you may
be able to use them in your Frappe apps or scripts.
The language for your session depends on the value of frappe.lang. This is
resolved in the following order:
- Form Dict > _lang
- Cookie > preferred_language [Guest User only]
- Request Header > Accept-Language [Guest User only]
- User document > language
- System Settings > language
Form Dict: _lang
The Form Dict's _lang parameter has the highest priority. Setting this will
update all translatable components in given request. Frappe uses this mechanism
in certain places to handle Email Templates and Print views.
Cookie: preferred_language
Although, it may not be practical to pass a ?_lang=ru in every request. If you
want persistent yet temporary language setting, you can set the
preferred_language key in cookies. Frappe utilizes this for the website
language switcher. This method may be used to persist language
based on the client.
Only considered for Guest Users. Ignored for logged in users.
Request Header: Accept-Language
Another relatively cleaner, and standard way to manage languages is using the
Accept-Language header. If the previous two methods aren't set, Frappe starts
resolving this header's values, which have an ordered set of a range of
acceptable languages by the client. You can check out the Mozilla
Docs
on this topic for more clarity perhaps.
Only considered for Guest Users. Ignored for logged in users.
User & System Settings
The User document has a language field that sets the session language for said
user. This setting persists across devices, clients. This allows a particular
user to view the website, and Desk in a language of their choice. Say for
instance, a user sets their language as "Russian" on a "French" site, when they
login, the site would be translated to Russian automatically.
The language field in the System Settings sets the language for the entire
site. It has the lowest priority and is the fallback language for all sessions.