ugettext and ugettext_lazy functions not recognized by makemessages in Python Django

Question

I'm working with Django 1.5.1 and I'm experiencing some "strange behaviour" with translations. I'm using ugettext and ugettext_lazy in the same Python file. If I organize the imports as:

from django.utils.translation import ugettext as trans
from django.utils.translation import ugettext_lazy as _

or

from django.utils.translation import ugettext as trans, ugettext_lazy as _

The strings marked as trans("string") are skipped when running makemessages command.

However, if I don't rename the ugettext it works well with both versions:

from django.utils.translation import ugettext
from django.utils.translation import ugettext_lazy as _

or

from django.utils.translation import ugettext, ugettext_lazy as _

Now trans("string") works well.

So, does anybody know why this import renaming is causing the renamed function not to be called? Is this an actual Python "limitation" I didn't know when renaming more than one function inside the same module?

---

UPDATE

After some testing, I've realized that even creating an empty python module inside an app with the following code it doesn't work:

from django.utils.translation import ugettext_lazy as translate

a = translate("string")

However, if using _ for the alias it works:

from django.utils.translation import ugettext_lazy as _

a = _("string")

My conclusion is: You can only use the _ alias for ugettext and ugettext_lazy (or any other related translation function) in Django or else it won't be recognized by makemessages command. The technical explanation can be found in Robert Lujo's answer.

Thanks!

Answer 1

Django command utility makemessages internally calls xgettext program like this:

cmd = (
    'xgettext -d %s -L Python %s %s --keyword=gettext_noop '
    '--keyword=gettext_lazy --keyword=ngettext_lazy:1,2 '
    '--keyword=ugettext_noop --keyword=ugettext_lazy '
    '--keyword=ungettext_lazy:1,2 --keyword=pgettext:1c,2 '
    '--keyword=npgettext:1c,2,3 --keyword=pgettext_lazy:1c,2 '
    '--keyword=npgettext_lazy:1c,2,3 --from-code UTF-8 '
    '--add-comments=Translators -o - "%s"' %
    (domain, wrap, location, work_file))

(source can be found here). So, some keywords are predefined by the xgettext utility (check reference for --keyword):

• for python - gettext, ugettext, dgettext, ngettext, ungettext, dngettext, _

and some are added by django utility:

• gettext_lazy , ngettext_lazy , ugettext_noop , ugettext_lazy , ungettext_lazy , pgettext , npgettext , pgettext_lazy , npgettext_lazy

Keyword trans is not in any of these keyword sets, so you should not use it for marking texts for translations.

Answer 2

Unexpected ugettext aliases can be handled by overriding the makemessages command, such as in:

from django.core.management.commands import makemessages

class Command(makemessages.Command):
    """
    Extends the makemessages command to look for additional aliases.
    """
    xgettext_options = makemessages.Command.xgettext_options + ['--keyword=_lazy']

See https://docs.djangoproject.com/en/1.8/topics/i18n/translation/#customizing-the-makemessages-command

Answer 3

These notes about multi-language support for Django project may let you identify what is wrong. Most probably renaming is not the root cause for failure.

Some warnings in these notes:

• Each template for your web site must load the i18n tag library using the {% load %}

• You need to create the locale directory manually before running makemessages - that you normally did, if not you get an error message

• Language files must be compiled to .mo files before you use them - that you did also

EDIT

In the page i linked to my post, they are using this syntax in templates:

{% trans "Hello" %}

is it something you tried already ?

Answer 4

Another way for resolving no .po files generation are the development server.

During my development server is running I executed the command makemessage. Command output was right, but my .po files were updated :

(venv_crypto_bot) macbook-pro:django_project dauzon$ python manage.py makemessages -a 
processing locale fr
processing locale en
processing locale ru

Stop the development server and re-run the command resolves my issue.

Answer 5

You can create your own compilemessages command, to call the original compilemessages command with extra arguments.

For example, to support from django.utils.translation import pgettext_lazy as _p:

# Created by [email protected] at 2022/4/20
from django.core.management import call_command
from django.core.management.base import BaseCommand
from django.core.management.commands import makemessages


class Command(BaseCommand):
    help = "Make messages in en_US and zh_CN, support _p, ignore venv folder."

    def handle(self, *args, **options):
        text = "-l en_US -l zh_CN --ignore ?env -v3"
        command = makemessages.Command()
        getattr(command, "xgettext_options").append("--keyword=_p:1c,2")
        call_command(command, *text.split())

Notes:

_p:1c,2 represents _p('msgctxt', 'msgid'), function with two arguments like pgettext_lazy