how to add new languages into Django? My language "Uyghur" or "Uighur" is not supported in Django

Add a non available language to your Django app

ISO language code of Uighur ئۇيغۇر تىلى is 'ug'.

In your settings.py:

from django.conf import global_settings

gettext_noop = lambda s: s

LANGUAGES = (
       ('ug', gettext_noop('Uighur')),
)

EXTRA_LANG_INFO = {
    'ug': {
        'bidi': True, # right-to-left
        'code': 'ug',
        'name': 'Uighur',
        'name_local': u'\u0626\u06C7\u064A\u063A\u06C7\u0631 \u062A\u0649\u0644\u0649', #unicode codepoints here
    },
}

# Add custom languages not provided by Django
import django.conf.locale
LANG_INFO = dict(django.conf.locale.LANG_INFO, **EXTRA_LANG_INFO)
django.conf.locale.LANG_INFO = LANG_INFO

# Languages using BiDi (right-to-left) layout
LANGUAGES_BIDI = global_settings.LANGUAGES_BIDI + ["ug"]

And:

manage.py makemessages -l ug
manage.py compilemessages

Based on laffuste's answer. First step, add language define in settings.py:

EXTRA_LANG_INFO = {
    'ms': {
        'bidi': False, # right-to-left
        'code': 'ms',
        'name': 'Bahasa Melayu',
        'name_local': u'Bahasa Melayu', #unicode codepoints here
    },
}

# Add custom languages not provided by Django
import django.conf.locale
from django.conf import global_settings
LANG_INFO = dict(django.conf.locale.LANG_INFO.items() + EXTRA_LANG_INFO.items())
django.conf.locale.LANG_INFO = LANG_INFO

# Languages using BiDi (right-to-left) layout
global_settings.LANGUAGES = global_settings.LANGUAGES + (("ms",'Bahasa Melayu'),)

Second step, Add locale in settings.py:

import os

PACKAGE_ROOT = os.path.abspath(os.path.dirname(__file__))
LOCALE_PATHS = (
    os.path.join(PACKAGE_ROOT, 'locale'),
)

Third step, Add locale defines in locale directory.

If someone encounters this, and will use the accepted answer (also check the comments on it) and still will have a redirect to /en/ instead of extra language - you need to create the .mo file for that locale. At least a dummy one.

Django checks if language is valid by checking if it can load the .mo file. There is no issue for standard languages because Django is shipped with a bunch of them, but for your custom language it doesn't exists.

I hope that will save your time.