.. _using-translations-in-your-own-projects:

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Using internationalization in your own projects

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At runtime, Django looks for translations by following this algorithm:

    * First, it looks for a ``locale`` directory in the directory containing

      your settings file.

    * Second, it looks for a ``locale`` directory in the project directory.

    * Third, it looks for a ``locale`` directory in each of the installed apps.

      It does this in the reverse order of INSTALLED_APPS

    * Finally, it checks the Django-provided base translation in

      ``django/conf/locale``.

In all cases the name of the directory containing the translation is expected to

be named using :term:`locale name` notation. E.g. ``de``, ``pt_BR``, ``es_AR``,

etc.

This way, you can write applications that include their own translations, and

you can override base translations in your project path. Or, you can just build

a big project out of several apps and put all translations into one big project

message file. The choice is yours.

.. note::

    If you're using manually configured settings, as described in

    :ref:`settings-without-django-settings-module`, the ``locale`` directory in

    the project directory will not be examined, since Django loses the ability

    to work out the location of the project directory. (Django normally uses the

    location of the settings file to determine this, and a settings file doesn't

    exist if you're manually configuring your settings.)

All message file repositories are structured the same way. They are:

    * ``$APPPATH/locale/<language>/LC_MESSAGES/django.(po|mo)``

    * ``$PROJECTPATH/locale/<language>/LC_MESSAGES/django.(po|mo)``

    * All paths listed in ``LOCALE_PATHS`` in your settings file are

      searched in that order for ``<language>/LC_MESSAGES/django.(po|mo)``

    * ``$PYTHONPATH/django/conf/locale/<language>/LC_MESSAGES/django.(po|mo)``

To create message files, you use the :djadmin:`django-admin.py makemessages <makemessages>`

tool. You only need to be in the same directory where the ``locale/`` directory

is located. And you use :djadmin:`django-admin.py compilemessages <compilemessages>`

to produce the binary ``.mo`` files that are used by ``gettext``. Read the

:doc:`/topics/i18n/localization` document for more details.

You can also run ``django-admin.py compilemessages --settings=path.to.settings``

to make the compiler process all the directories in your :setting:`LOCALE_PATHS`

setting.

Application message files are a bit complicated to discover -- they need the

:class:`~django.middleware.locale.LocaleMiddleware`. If you don't use the

middleware, only the Django message files and project message files will be

installed and available at runtime.

Finally, you should give some thought to the structure of your translation

files. If your applications need to be delivered to other users and will

be used in other projects, you might want to use app-specific translations.

But using app-specific translations and project translations could produce

weird problems with ``makemessages``: It will traverse all directories below

the current path and so might put message IDs into the project message file

that are already in application message files.

The easiest way out is to store applications that are not part of the project

(and so carry their own translations) outside the project tree. That way,

``django-admin.py makemessages`` on the project level will only translate

strings that are connected to your explicit project and not strings that are

distributed independently.

Using translations outside views and templates

==============================================

While Django provides a rich set of i18n tools for use in views and templates,

it does not restrict the usage to Django-specific code. The Django translation

mechanisms can be used to translate arbitrary texts to any language that is

supported by Django (as long as an appropriate translation catalog exists, of

course). You can load a translation catalog, activate it and translate text to

language of your choice, but remember to switch back to original language, as

activating a translation catalog is done on per-thread basis and such change

will affect code running in the same thread.

For example::

    from django.utils import translation

    def welcome_translated(language):

        cur_language = translation.get_language()

        try:

            translation.activate(language)

            text = translation.ugettext('welcome')

        finally:

            translation.activate(cur_language)

        return text

Calling this function with the value 'de' will give you ``"Willkommen"``,

regardless of :setting:`LANGUAGE_CODE` and language set by middleware.

Functions of particular interest are ``django.utils.translation.get_language()``

which returns the language used in the current thread,

``django.utils.translation.activate()`` which activates a translation catalog

for the current thread, and ``django.utils.translation.check_for_language()``

which checks if the given language is supported by Django.