Supporting multiple languages for a Django web application is straight forward. 1) Add the LocaleMiddleWare to the list of middlewares. 2) Supply languages files with translations in PO files. 3) The PO files are compiled into MO files. When a request is encountered django checks into the following places for the required lannguage; the url for a prefix, the session, a language cookie and Accept-Language header in that order. This order can be seen in the locale middleware code at django > middleware > locale. Once the required language is identified, it is activated.
Within the application a user can have a preferred language. This is implemented the same way as preferred timezone. Users can go into their preferences page and choose from a list of supported languages. Currently English, Dutch, Swedish, Norwegian and French languages are supported. Two users with Dutch and Swedish language preferences are shown below.
When a user accesses the application for the first time the login page is shown in a language as on the Accept-Language header from the browser. Here Chrome was set to French (browser settings shown in the end) and Opera in default language settings. Login based on request headers (for users above) is shown below.
The following screens show the two users accessing the application after logging in. For both the browsers the first language was what the browser mentioned in the request header. Once the user logs in the user's preferred language is activated. This is shown below where the preferred language of user on left is Dutch and Swedish on the right.
Chrome language settings indicating French selection is as follows.
References
Django docs on translation
https://docs.djangoproject.com/en/2.1/topics/i18n/translation/
