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984 lines
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984 lines
40 KiB
Plaintext
.. _topics-i18n:
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====================
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Internationalization
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====================
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Django has full support for internationalization of text in code and templates.
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Here's how it works.
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Overview
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========
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The goal of internationalization is to allow a single Web application to offer
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its content and functionality in multiple languages.
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You, the Django developer, can accomplish this goal by adding a minimal amount
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of hooks to your Python code and templates. These hooks are called
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**translation strings**. They tell Django: "This text should be translated into
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the end user's language, if a translation for this text is available in that
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language."
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Django takes care of using these hooks to translate Web apps, on the fly,
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according to users' language preferences.
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Essentially, Django does two things:
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* It lets developers and template authors specify which parts of their apps
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should be translatable.
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* It uses these hooks to translate Web apps for particular users according
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to their language preferences.
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If you don't need internationalization in your app
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==================================================
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Django's internationalization hooks are on by default, and that means there's a
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bit of i18n-related overhead in certain places of the framework. If you don't
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use internationalization, you should take the two seconds to set
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:setting:`USE_I18N = False <USE_I18N>` in your settings file. If
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:setting:`USE_I18N` is set to ``False``, then Django will make some
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optimizations so as not to load the internationalization machinery.
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You'll probably also want to remove ``'django.core.context_processors.i18n'``
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from your ``TEMPLATE_CONTEXT_PROCESSORS`` setting.
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If you do need internationalization: three steps
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================================================
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1. Embed translation strings in your Python code and templates.
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2. Get translations for those strings, in whichever languages you want to
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support.
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3. Activate the locale middleware in your Django settings.
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.. admonition:: Behind the scenes
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Django's translation machinery uses the standard ``gettext`` module that
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comes with Python.
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1. How to specify translation strings
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=====================================
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Translation strings specify "This text should be translated." These strings can
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appear in your Python code and templates. It's your responsibility to mark
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translatable strings; the system can only translate strings it knows about.
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In Python code
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--------------
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Standard translation
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~~~~~~~~~~~~~~~~~~~~
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Specify a translation string by using the function ``ugettext()``. It's
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convention to import this as a shorter alias, ``_``, to save typing.
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.. note::
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Python's standard library ``gettext`` module installs ``_()`` into the
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global namespace, as an alias for ``gettext()``. In Django, we have chosen
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not to follow this practice, for a couple of reasons:
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1. For international character set (Unicode) support, ``ugettext()`` is
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more useful than ``gettext()``. Sometimes, you should be using
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``ugettext_lazy()`` as the default translation method for a particular
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file. Without ``_()`` in the global namespace, the developer has to
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think about which is the most appropriate translation function.
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2. The underscore character (``_``) is used to represent "the previous
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result" in Python's interactive shell and doctest tests. Installing a
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global ``_()`` function causes interference. Explicitly importing
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``ugettext()`` as ``_()`` avoids this problem.
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.. highlightlang:: python
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In this example, the text ``"Welcome to my site."`` is marked as a translation
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string::
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from django.utils.translation import ugettext as _
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def my_view(request):
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output = _("Welcome to my site.")
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return HttpResponse(output)
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Obviously, you could code this without using the alias. This example is
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identical to the previous one::
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from django.utils.translation import ugettext
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def my_view(request):
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output = ugettext("Welcome to my site.")
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return HttpResponse(output)
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Translation works on computed values. This example is identical to the previous
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two::
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def my_view(request):
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words = ['Welcome', 'to', 'my', 'site.']
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output = _(' '.join(words))
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return HttpResponse(output)
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Translation works on variables. Again, here's an identical example::
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def my_view(request):
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sentence = 'Welcome to my site.'
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output = _(sentence)
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return HttpResponse(output)
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(The caveat with using variables or computed values, as in the previous two
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examples, is that Django's translation-string-detecting utility,
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``django-admin.py makemessages``, won't be able to find these strings. More on
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``makemessages`` later.)
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The strings you pass to ``_()`` or ``ugettext()`` can take placeholders,
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specified with Python's standard named-string interpolation syntax. Example::
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def my_view(request, m, d):
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output = _('Today is %(month)s, %(day)s.') % {'month': m, 'day': d}
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return HttpResponse(output)
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This technique lets language-specific translations reorder the placeholder
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text. For example, an English translation may be ``"Today is November, 26."``,
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while a Spanish translation may be ``"Hoy es 26 de Noviembre."`` -- with the
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placeholders (the month and the day) with their positions swapped.
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For this reason, you should use named-string interpolation (e.g., ``%(day)s``)
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instead of positional interpolation (e.g., ``%s`` or ``%d``) whenever you
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have more than a single parameter. If you used positional interpolation,
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translations wouldn't be able to reorder placeholder text.
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Marking strings as no-op
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~~~~~~~~~~~~~~~~~~~~~~~~
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Use the function ``django.utils.translation.ugettext_noop()`` to mark a string
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as a translation string without translating it. The string is later translated
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from a variable.
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Use this if you have constant strings that should be stored in the source
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language because they are exchanged over systems or users -- such as strings in
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a database -- but should be translated at the last possible point in time, such
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as when the string is presented to the user.
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.. _lazy-translations:
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Lazy translation
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~~~~~~~~~~~~~~~~
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Use the function ``django.utils.translation.ugettext_lazy()`` to translate
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strings lazily -- when the value is accessed rather than when the
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``ugettext_lazy()`` function is called.
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For example, to translate a model's ``help_text``, do the following::
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from django.utils.translation import ugettext_lazy
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class MyThing(models.Model):
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name = models.CharField(help_text=ugettext_lazy('This is the help text'))
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In this example, ``ugettext_lazy()`` stores a lazy reference to the string --
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not the actual translation. The translation itself will be done when the string
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is used in a string context, such as template rendering on the Django admin site.
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If you don't like the verbose name ``ugettext_lazy``, you can just alias it as
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``_`` (underscore), like so::
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from django.utils.translation import ugettext_lazy as _
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class MyThing(models.Model):
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name = models.CharField(help_text=_('This is the help text'))
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Always use lazy translations in :ref:`Django models <topics-db-models>`.
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Field names and table names should be marked for translation (otherwise, they
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won't be translated in the admin interface). This means writing explicit
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``verbose_name`` and ``verbose_name_plural`` options in the ``Meta`` class,
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though, rather than relying on Django's default determination of
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``verbose_name`` and ``verbose_name_plural`` by looking at the model's class
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name::
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from django.utils.translation import ugettext_lazy as _
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class MyThing(models.Model):
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name = models.CharField(_('name'), help_text=_('This is the help text'))
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class Meta:
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verbose_name = _('my thing')
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verbose_name_plural = _('mythings')
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Pluralization
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~~~~~~~~~~~~~
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Use the function ``django.utils.translation.ungettext()`` to specify pluralized
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messages. Example::
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from django.utils.translation import ungettext
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def hello_world(request, count):
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page = ungettext('there is %(count)d object', 'there are %(count)d objects', count) % {
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'count': count,
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}
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return HttpResponse(page)
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``ungettext`` takes three arguments: the singular translation string, the plural
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translation string and the number of objects (which is passed to the
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translation languages as the ``count`` variable).
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In template code
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----------------
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.. highlightlang:: html+django
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Translations in :ref:`Django templates <topics-templates>` uses two template
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tags and a slightly different syntax than in Python code. To give your template
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access to these tags, put ``{% load i18n %}`` toward the top of your template.
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The ``{% trans %}`` template tag translates either a constant string
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(enclosed in single or double quotes) or variable content::
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<title>{% trans "This is the title." %}</title>
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<title>{% trans myvar %}</title>
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If the ``noop`` option is present, variable lookup still takes place but the
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translation is skipped. This is useful when "stubbing out" content that will
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require translation in the future::
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<title>{% trans "myvar" noop %}</title>
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It's not possible to mix a template variable inside a string within ``{% trans
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%}``. If your translations require strings with variables (placeholders), use
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``{% blocktrans %}``::
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{% blocktrans %}This string will have {{ value }} inside.{% endblocktrans %}
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To translate a template expression -- say, using template filters -- you need
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to bind the expression to a local variable for use within the translation
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block::
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{% blocktrans with value|filter as myvar %}
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This will have {{ myvar }} inside.
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{% endblocktrans %}
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If you need to bind more than one expression inside a ``blocktrans`` tag,
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separate the pieces with ``and``::
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{% blocktrans with book|title as book_t and author|title as author_t %}
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This is {{ book_t }} by {{ author_t }}
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{% endblocktrans %}
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To pluralize, specify both the singular and plural forms with the
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``{% plural %}`` tag, which appears within ``{% blocktrans %}`` and
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``{% endblocktrans %}``. Example::
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{% blocktrans count list|length as counter %}
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There is only one {{ name }} object.
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{% plural %}
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There are {{ counter }} {{ name }} objects.
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{% endblocktrans %}
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Internally, all block and inline translations use the appropriate
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``ugettext`` / ``ungettext`` call.
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Each ``RequestContext`` has access to three translation-specific variables:
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* ``LANGUAGES`` is a list of tuples in which the first element is the
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language code and the second is the language name (translated into the
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currently active locale).
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* ``LANGUAGE_CODE`` is the current user's preferred language, as a string.
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Example: ``en-us``. (See "How language preference is discovered", below.)
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* ``LANGUAGE_BIDI`` is the current locale's direction. If True, it's a
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right-to-left language, e.g.: Hebrew, Arabic. If False it's a
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left-to-right language, e.g.: English, French, German etc.
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If you don't use the ``RequestContext`` extension, you can get those values with
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three tags::
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{% get_current_language as LANGUAGE_CODE %}
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{% get_available_languages as LANGUAGES %}
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{% get_current_language_bidi as LANGUAGE_BIDI %}
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These tags also require a ``{% load i18n %}``.
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Translation hooks are also available within any template block tag that accepts
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constant strings. In those cases, just use ``_()`` syntax to specify a
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translation string::
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{% some_special_tag _("Page not found") value|yesno:_("yes,no") %}
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In this case, both the tag and the filter will see the already-translated
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string, so they don't need to be aware of translations.
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.. note::
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In this example, the translation infrastructure will be passed the string
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``"yes,no"``, not the individual strings ``"yes"`` and ``"no"``. The
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translated string will need to contain the comma so that the filter
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parsing code knows how to split up the arguments. For example, a German
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translator might translate the string ``"yes,no"`` as ``"ja,nein"``
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(keeping the comma intact).
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.. _Django templates: ../templates_python/
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Working with lazy translation objects
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-------------------------------------
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.. highlightlang:: python
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Using ``ugettext_lazy()`` and ``ungettext_lazy()`` to mark strings in models
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and utility functions is a common operation. When you're working with these
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objects elsewhere in your code, you should ensure that you don't accidentally
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convert them to strings, because they should be converted as late as possible
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(so that the correct locale is in effect). This necessitates the use of a
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couple of helper functions.
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Joining strings: string_concat()
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Standard Python string joins (``''.join([...])``) will not work on lists
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containing lazy translation objects. Instead, you can use
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``django.utils.translation.string_concat()``, which creates a lazy object that
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concatenates its contents *and* converts them to strings only when the result
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is included in a string. For example::
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from django.utils.translation import string_concat
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...
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name = ugettext_lazy(u'John Lennon')
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instrument = ugettext_lazy(u'guitar')
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result = string_concat([name, ': ', instrument])
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In this case, the lazy translations in ``result`` will only be converted to
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strings when ``result`` itself is used in a string (usually at template
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rendering time).
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The allow_lazy() decorator
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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Django offers many utility functions (particularly in ``django.utils``) that
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take a string as their first argument and do something to that string. These
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functions are used by template filters as well as directly in other code.
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If you write your own similar functions and deal with translations, you'll
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face the problem of what to do when the first argument is a lazy translation
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object. You don't want to convert it to a string immediately, because you might
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be using this function outside of a view (and hence the current thread's locale
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setting will not be correct).
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For cases like this, use the ``django.utils.functional.allow_lazy()``
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decorator. It modifies the function so that *if* it's called with a lazy
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translation as the first argument, the function evaluation is delayed until it
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needs to be converted to a string.
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For example::
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from django.utils.functional import allow_lazy
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def fancy_utility_function(s, ...):
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# Do some conversion on string 's'
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...
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fancy_utility_function = allow_lazy(fancy_utility_function, unicode)
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The ``allow_lazy()`` decorator takes, in addition to the function to decorate,
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a number of extra arguments (``*args``) specifying the type(s) that the
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original function can return. Usually, it's enough to include ``unicode`` here
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and ensure that your function returns only Unicode strings.
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Using this decorator means you can write your function and assume that the
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input is a proper string, then add support for lazy translation objects at the
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end.
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.. _how-to-create-language-files:
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2. How to create language files
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===============================
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Once you've tagged your strings for later translation, you need to write (or
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obtain) the language translations themselves. Here's how that works.
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.. admonition:: Locale restrictions
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Django does not support localizing your application into a locale for
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which Django itself has not been translated. In this case, it will ignore
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your translation files. If you were to try this and Django supported it,
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you would inevitably see a mixture of translated strings (from your
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application) and English strings (from Django itself). If you want to
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support a locale for your application that is not already part of
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Django, you'll need to make at least a minimal translation of the Django
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core. See the relevant :ref:`LocaleMiddleware note<locale-middleware-notes>`
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for more details.
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Message files
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-------------
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The first step is to create a **message file** for a new language. A message
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file is a plain-text file, representing a single language, that contains all
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available translation strings and how they should be represented in the given
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language. Message files have a ``.po`` file extension.
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Django comes with a tool, ``django-admin.py makemessages``, that automates the
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creation and upkeep of these files.
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.. admonition:: A note to Django veterans
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The old tool ``bin/make-messages.py`` has been moved to the command
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``django-admin.py makemessages`` to provide consistency throughout Django.
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To create or update a message file, run this command::
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django-admin.py makemessages -l de
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...where ``de`` is the language code for the message file you want to create.
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The language code, in this case, is in locale format. For example, it's
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``pt_BR`` for Brazilian Portuguese and ``de_AT`` for Austrian German.
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The script should be run from one of three places:
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* The root directory of your Django project.
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* The root directory of your Django app.
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* The root ``django`` directory (not a Subversion checkout, but the one
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that is linked-to via ``$PYTHONPATH`` or is located somewhere on that
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path). This is only relevant when you are creating a translation for
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Django itself, see :ref:`contributing-translations`.
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Th script runs over your project source tree or your application source tree and
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pulls out all strings marked for translation. It creates (or updates) a message
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file in the directory ``locale/LANG/LC_MESSAGES``. In the ``de`` example, the
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file will be ``locale/de/LC_MESSAGES/django.po``.
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By default ``django-admin.py makemessages`` examines every file that has the
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``.html`` file extension. In case you want to override that default, use the
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``--extension`` or ``-e`` option to specify the file extensions to examine::
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django-admin.py makemessages -l de -e txt
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Separate multiple extensions with commas and/or use ``-e`` or ``--extension``
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multiple times::
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django-admin.py makemessages -l=de -e=html,txt -e xml
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When `creating JavaScript translation catalogs`_ you need to use the special
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'djangojs' domain, **not** ``-e js``.
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.. _create a JavaScript translation catalog: `Creating JavaScript translation catalogs`_
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.. admonition:: No gettext?
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If you don't have the ``gettext`` utilities installed, ``django-admin.py
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makemessages`` will create empty files. If that's the case, either install
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the ``gettext`` utilities or just copy the English message file
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(``locale/en/LC_MESSAGES/django.po``) if available and use it as a starting
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point; it's just an empty translation file.
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.. admonition:: Working on Windows?
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If you're using Windows and need to install the GNU gettext utilities so
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``django-admin makemessages`` works see `gettext on Windows`_ for more
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information.
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The format of ``.po`` files is straightforward. Each ``.po`` file contains a
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small bit of metadata, such as the translation maintainer's contact
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information, but the bulk of the file is a list of **messages** -- simple
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mappings between translation strings and the actual translated text for the
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particular language.
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For example, if your Django app contained a translation string for the text
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``"Welcome to my site."``, like so::
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_("Welcome to my site.")
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...then ``django-admin.py makemessages`` will have created a ``.po`` file
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containing the following snippet -- a message::
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#: path/to/python/module.py:23
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msgid "Welcome to my site."
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msgstr ""
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A quick explanation:
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* ``msgid`` is the translation string, which appears in the source. Don't
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change it.
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* ``msgstr`` is where you put the language-specific translation. It starts
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out empty, so it's your responsibility to change it. Make sure you keep
|
|
the quotes around your translation.
|
|
* As a convenience, each message includes, in the form of a comment line
|
|
prefixed with ``#`` and locted above the ``msgid`` line, the filename and
|
|
line number from which the translation string was gleaned.
|
|
|
|
Long messages are a special case. There, the first string directly after the
|
|
``msgstr`` (or ``msgid``) is an empty string. Then the content itself will be
|
|
written over the next few lines as one string per line. Those strings are
|
|
directly concatenated. Don't forget trailing spaces within the strings;
|
|
otherwise, they'll be tacked together without whitespace!
|
|
|
|
.. admonition:: Mind your charset
|
|
|
|
When creating a PO file with your favorite text editor, first edit
|
|
the charset line (search for ``"CHARSET"``) and set it to the charset
|
|
you'll be using to edit the content. Due to the way the ``gettext`` tools
|
|
work internally and because we want to allow non-ASCII source strings in
|
|
Django's core and your applications, you **must** use UTF-8 as the encoding
|
|
for your PO file. This means that everybody will be using the same
|
|
encoding, which is important when Django processes the PO files.
|
|
|
|
To reexamine all source code and templates for new translation strings and
|
|
update all message files for **all** languages, run this::
|
|
|
|
django-admin.py makemessages -a
|
|
|
|
Compiling message files
|
|
-----------------------
|
|
|
|
After you create your message file -- and each time you make changes to it --
|
|
you'll need to compile it into a more efficient form, for use by ``gettext``.
|
|
Do this with the ``django-admin.py compilemessages`` utility.
|
|
|
|
This tool runs over all available ``.po`` files and creates ``.mo`` files, which
|
|
are binary files optimized for use by ``gettext``. In the same directory from
|
|
which you ran ``django-admin.py makemessages``, run ``django-admin.py
|
|
compilemessages`` like this::
|
|
|
|
django-admin.py compilemessages
|
|
|
|
That's it. Your translations are ready for use.
|
|
|
|
.. admonition:: A note to Django veterans
|
|
|
|
The old tool ``bin/compile-messages.py`` has been moved to the command
|
|
``django-admin.py compilemessages`` to provide consistency throughout
|
|
Django.
|
|
|
|
.. admonition:: Working on Windows?
|
|
|
|
If you're using Windows and need to install the GNU gettext utilities so
|
|
``django-admin compilemessages`` works see `gettext on Windows`_ for more
|
|
information.
|
|
|
|
3. How Django discovers language preference
|
|
===========================================
|
|
|
|
Once you've prepared your translations -- or, if you just want to use the
|
|
translations that come with Django -- you'll just need to activate translation
|
|
for your app.
|
|
|
|
Behind the scenes, Django has a very flexible model of deciding which language
|
|
should be used -- installation-wide, for a particular user, or both.
|
|
|
|
To set an installation-wide language preference, set :setting:`LANGUAGE_CODE`.
|
|
Django uses this language as the default translation -- the final attempt if no
|
|
other translator finds a translation.
|
|
|
|
If all you want to do is run Django with your native language, and a language
|
|
file is available for your language, all you need to do is set
|
|
``LANGUAGE_CODE``.
|
|
|
|
If you want to let each individual user specify which language he or she
|
|
prefers, use ``LocaleMiddleware``. ``LocaleMiddleware`` enables language
|
|
selection based on data from the request. It customizes content for each user.
|
|
|
|
To use ``LocaleMiddleware``, add ``'django.middleware.locale.LocaleMiddleware'``
|
|
to your ``MIDDLEWARE_CLASSES`` setting. Because middleware order matters, you
|
|
should follow these guidelines:
|
|
|
|
* Make sure it's one of the first middlewares installed.
|
|
* It should come after ``SessionMiddleware``, because ``LocaleMiddleware``
|
|
makes use of session data.
|
|
* If you use ``CacheMiddleware``, put ``LocaleMiddleware`` after it.
|
|
|
|
For example, your ``MIDDLEWARE_CLASSES`` might look like this::
|
|
|
|
MIDDLEWARE_CLASSES = (
|
|
'django.contrib.sessions.middleware.SessionMiddleware',
|
|
'django.middleware.locale.LocaleMiddleware',
|
|
'django.middleware.common.CommonMiddleware',
|
|
)
|
|
|
|
(For more on middleware, see the :ref:`middleware documentation
|
|
<topics-http-middleware>`.)
|
|
|
|
``LocaleMiddleware`` tries to determine the user's language preference by
|
|
following this algorithm:
|
|
|
|
* First, it looks for a ``django_language`` key in the current user's
|
|
session.
|
|
|
|
* Failing that, it looks for a cookie.
|
|
|
|
.. versionchanged:: 1.0
|
|
|
|
In Django version 0.96 and before, the cookie's name is hard-coded to
|
|
``django_language``. In Django 1,0, The cookie name is set by the
|
|
``LANGUAGE_COOKIE_NAME`` setting. (The default name is
|
|
``django_language``.)
|
|
|
|
* Failing that, it looks at the ``Accept-Language`` HTTP header. This
|
|
header is sent by your browser and tells the server which language(s) you
|
|
prefer, in order by priority. Django tries each language in the header
|
|
until it finds one with available translations.
|
|
|
|
* Failing that, it uses the global ``LANGUAGE_CODE`` setting.
|
|
|
|
.. _locale-middleware-notes:
|
|
|
|
Notes:
|
|
|
|
* In each of these places, the language preference is expected to be in the
|
|
standard language format, as a string. For example, Brazilian Portuguese
|
|
is ``pt-br``.
|
|
|
|
* If a base language is available but the sublanguage specified is not,
|
|
Django uses the base language. For example, if a user specifies ``de-at``
|
|
(Austrian German) but Django only has ``de`` available, Django uses
|
|
``de``.
|
|
|
|
* Only languages listed in the :setting:`LANGUAGES` setting can be selected.
|
|
If you want to restrict the language selection to a subset of provided
|
|
languages (because your application doesn't provide all those languages),
|
|
set ``LANGUAGES`` to a list of languages. For example::
|
|
|
|
LANGUAGES = (
|
|
('de', _('German')),
|
|
('en', _('English')),
|
|
)
|
|
|
|
This example restricts languages that are available for automatic
|
|
selection to German and English (and any sublanguage, like de-ch or
|
|
en-us).
|
|
|
|
.. _LANGUAGES setting: ../settings/#languages
|
|
|
|
* If you define a custom ``LANGUAGES`` setting, as explained in the
|
|
previous bullet, it's OK to mark the languages as translation strings
|
|
-- but use a "dummy" ``ugettext()`` function, not the one in
|
|
``django.utils.translation``. You should *never* import
|
|
``django.utils.translation`` from within your settings file, because that
|
|
module in itself depends on the settings, and that would cause a circular
|
|
import.
|
|
|
|
The solution is to use a "dummy" ``ugettext()`` function. Here's a sample
|
|
settings file::
|
|
|
|
ugettext = lambda s: s
|
|
|
|
LANGUAGES = (
|
|
('de', ugettext('German')),
|
|
('en', ugettext('English')),
|
|
)
|
|
|
|
With this arrangement, ``django-admin.py makemessages`` will still find
|
|
and mark these strings for translation, but the translation won't happen
|
|
at runtime -- so you'll have to remember to wrap the languages in the
|
|
*real* ``ugettext()`` in any code that uses ``LANGUAGES`` at runtime.
|
|
|
|
* The ``LocaleMiddleware`` can only select languages for which there is a
|
|
Django-provided base translation. If you want to provide translations
|
|
for your application that aren't already in the set of translations
|
|
in Django's source tree, you'll want to provide at least basic
|
|
translations for that language. For example, Django uses technical
|
|
message IDs to translate date formats and time formats -- so you will
|
|
need at least those translations for the system to work correctly.
|
|
|
|
A good starting point is to copy the English ``.po`` file and to
|
|
translate at least the technical messages -- maybe the validation
|
|
messages, too.
|
|
|
|
Technical message IDs are easily recognized; they're all upper case. You
|
|
don't translate the message ID as with other messages, you provide the
|
|
correct local variant on the provided English value. For example, with
|
|
``DATETIME_FORMAT`` (or ``DATE_FORMAT`` or ``TIME_FORMAT``), this would
|
|
be the format string that you want to use in your language. The format
|
|
is identical to the format strings used by the ``now`` template tag.
|
|
|
|
Once ``LocaleMiddleware`` determines the user's preference, it makes this
|
|
preference available as ``request.LANGUAGE_CODE`` for each
|
|
:class:`~django.http.HttpRequest`. Feel free to read this value in your view
|
|
code. Here's a simple example::
|
|
|
|
def hello_world(request, count):
|
|
if request.LANGUAGE_CODE == 'de-at':
|
|
return HttpResponse("You prefer to read Austrian German.")
|
|
else:
|
|
return HttpResponse("You prefer to read another language.")
|
|
|
|
Note that, with static (middleware-less) translation, the language is in
|
|
``settings.LANGUAGE_CODE``, while with dynamic (middleware) translation, it's
|
|
in ``request.LANGUAGE_CODE``.
|
|
|
|
.. _settings file: ../settings/
|
|
.. _middleware documentation: ../middleware/
|
|
.. _session: ../sessions/
|
|
.. _request object: ../request_response/#httprequest-objects
|
|
|
|
.. _translations-in-your-own-projects:
|
|
|
|
Using translations in your own projects
|
|
=======================================
|
|
|
|
Django looks for translations by following this algorithm:
|
|
|
|
* First, it looks for a ``locale`` directory in the application directory
|
|
of the view that's being called. If it finds a translation for the
|
|
selected language, the translation will be installed.
|
|
* Next, it looks for a ``locale`` directory in the project directory. If it
|
|
finds a translation, the translation will be installed.
|
|
* Finally, it checks the Django-provided base translation in
|
|
``django/conf/locale``.
|
|
|
|
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
|
|
: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 same ``django-admin.py makemessages``
|
|
tool as with the Django message files. You only need to be in the right place
|
|
-- in the directory where either the ``conf/locale`` (in case of the source
|
|
tree) or the ``locale/`` (in case of app messages or project messages)
|
|
directory are located. And you use the same ``django-admin.py compilemessages``
|
|
to produce the binary ``django.mo`` files that are used by ``gettext``.
|
|
|
|
You can also run ``django-admin.py compilemessages --settings=path.to.settings``
|
|
to make the compiler process all the directories in your ``LOCALE_PATHS``
|
|
setting.
|
|
|
|
Application message files are a bit complicated to discover -- they need the
|
|
``LocaleMiddleware``. If you don't use the middleware, only the Django message
|
|
files and project message files will be processed.
|
|
|
|
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``: ``makemessages`` 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.
|
|
|
|
The ``set_language`` redirect view
|
|
==================================
|
|
|
|
As a convenience, Django comes with a view, ``django.views.i18n.set_language``,
|
|
that sets a user's language preference and redirects back to the previous page.
|
|
|
|
Activate this view by adding the following line to your URLconf::
|
|
|
|
(r'^i18n/', include('django.conf.urls.i18n')),
|
|
|
|
(Note that this example makes the view available at ``/i18n/setlang/``.)
|
|
|
|
The view expects to be called via the ``POST`` method, with a ``language``
|
|
parameter set in request. If session support is enabled, the view
|
|
saves the language choice in the user's session. Otherwise, it saves the
|
|
language choice in a cookie that is by default named ``django_language``.
|
|
(The name can be changed through the ``LANGUAGE_COOKIE_NAME`` setting if you're
|
|
using the Django development version.)
|
|
|
|
After setting the language choice, Django redirects the user, following this
|
|
algorithm:
|
|
|
|
* Django looks for a ``next`` parameter in the ``POST`` data.
|
|
* If that doesn't exist, or is empty, Django tries the URL in the
|
|
``Referrer`` header.
|
|
* If that's empty -- say, if a user's browser suppresses that header --
|
|
then the user will be redirected to ``/`` (the site root) as a fallback.
|
|
|
|
Here's example HTML template code:
|
|
|
|
.. code-block:: html+django
|
|
|
|
<form action="/i18n/setlang/" method="post">
|
|
<input name="next" type="hidden" value="/next/page/" />
|
|
<select name="language">
|
|
{% for lang in LANGUAGES %}
|
|
<option value="{{ lang.0 }}">{{ lang.1 }}</option>
|
|
{% endfor %}
|
|
</select>
|
|
<input type="submit" value="Go" />
|
|
</form>
|
|
|
|
Translations and JavaScript
|
|
===========================
|
|
|
|
Adding translations to JavaScript poses some problems:
|
|
|
|
* JavaScript code doesn't have access to a ``gettext`` implementation.
|
|
|
|
* JavaScript code doesn't have access to .po or .mo files; they need to be
|
|
delivered by the server.
|
|
|
|
* The translation catalogs for JavaScript should be kept as small as
|
|
possible.
|
|
|
|
Django provides an integrated solution for these problems: It passes the
|
|
translations into JavaScript, so you can call ``gettext``, etc., from within
|
|
JavaScript.
|
|
|
|
The ``javascript_catalog`` view
|
|
-------------------------------
|
|
|
|
The main solution to these problems is the ``javascript_catalog`` view, which
|
|
sends out a JavaScript code library with functions that mimic the ``gettext``
|
|
interface, plus an array of translation strings. Those translation strings are
|
|
taken from the application, project or Django core, according to what you
|
|
specify in either the info_dict or the URL.
|
|
|
|
You hook it up like this::
|
|
|
|
js_info_dict = {
|
|
'packages': ('your.app.package',),
|
|
}
|
|
|
|
urlpatterns = patterns('',
|
|
(r'^jsi18n/$', 'django.views.i18n.javascript_catalog', js_info_dict),
|
|
)
|
|
|
|
Each string in ``packages`` should be in Python dotted-package syntax (the
|
|
same format as the strings in ``INSTALLED_APPS``) and should refer to a package
|
|
that contains a ``locale`` directory. If you specify multiple packages, all
|
|
those catalogs are merged into one catalog. This is useful if you have
|
|
JavaScript that uses strings from different applications.
|
|
|
|
You can make the view dynamic by putting the packages into the URL pattern::
|
|
|
|
urlpatterns = patterns('',
|
|
(r'^jsi18n/(?P<packages>\S+?)/$', 'django.views.i18n.javascript_catalog'),
|
|
)
|
|
|
|
With this, you specify the packages as a list of package names delimited by '+'
|
|
signs in the URL. This is especially useful if your pages use code from
|
|
different apps and this changes often and you don't want to pull in one big
|
|
catalog file. As a security measure, these values can only be either
|
|
``django.conf`` or any package from the ``INSTALLED_APPS`` setting.
|
|
|
|
Using the JavaScript translation catalog
|
|
----------------------------------------
|
|
|
|
To use the catalog, just pull in the dynamically generated script like this::
|
|
|
|
<script type="text/javascript" src="/path/to/jsi18n/"></script>
|
|
|
|
This is how the admin fetches the translation catalog from the server. When the
|
|
catalog is loaded, your JavaScript code can use the standard ``gettext``
|
|
interface to access it::
|
|
|
|
document.write(gettext('this is to be translated'));
|
|
|
|
There is also an ``ngettext`` interface::
|
|
|
|
var object_cnt = 1 // or 0, or 2, or 3, ...
|
|
s = ngettext('literal for the singular case',
|
|
'literal for the plural case', object_cnt);
|
|
|
|
and even a string interpolation function::
|
|
|
|
function interpolate(fmt, obj, named);
|
|
|
|
The interpolation syntax is borrowed from Python, so the ``interpolate``
|
|
function supports both positional and named interpolation:
|
|
|
|
* Positional interpolation: ``obj`` contains a JavaScript Array object
|
|
whose elements values are then sequentially interpolated in their
|
|
corresponding ``fmt`` placeholders in the same order they appear.
|
|
For example::
|
|
|
|
fmts = ngettext('There is %s object. Remaining: %s',
|
|
'There are %s objects. Remaining: %s', 11);
|
|
s = interpolate(fmts, [11, 20]);
|
|
// s is 'There are 11 objects. Remaining: 20'
|
|
|
|
* Named interpolation: This mode is selected by passing the optional
|
|
boolean ``named`` parameter as true. ``obj`` contains a JavaScript
|
|
object or associative array. For example::
|
|
|
|
d = {
|
|
count: 10
|
|
total: 50
|
|
};
|
|
|
|
fmts = ngettext('Total: %(total)s, there is %(count)s object',
|
|
'there are %(count)s of a total of %(total)s objects', d.count);
|
|
s = interpolate(fmts, d, true);
|
|
|
|
You shouldn't go over the top with string interpolation, though: this is still
|
|
JavaScript, so the code has to make repeated regular-expression substitutions.
|
|
This isn't as fast as string interpolation in Python, so keep it to those
|
|
cases where you really need it (for example, in conjunction with ``ngettext``
|
|
to produce proper pluralizations).
|
|
|
|
Creating JavaScript translation catalogs
|
|
----------------------------------------
|
|
|
|
You create and update the translation catalogs the same way as the other
|
|
|
|
Django translation catalogs -- with the django-admin.py makemessages tool. The
|
|
only difference is you need to provide a ``-d djangojs`` parameter, like this::
|
|
|
|
django-admin.py makemessages -d djangojs -l de
|
|
|
|
This would create or update the translation catalog for JavaScript for German.
|
|
After updating translation catalogs, just run ``django-admin.py compilemessages``
|
|
the same way as you do with normal Django translation catalogs.
|
|
|
|
Specialties of Django translation
|
|
==================================
|
|
|
|
If you know ``gettext``, you might note these specialties in the way Django
|
|
does translation:
|
|
|
|
* The string domain is ``django`` or ``djangojs``. This string domain is
|
|
used to differentiate between different programs that store their data
|
|
in a common message-file library (usually ``/usr/share/locale/``). The
|
|
``django`` domain is used for python and template translation strings
|
|
and is loaded into the global translation catalogs. The ``djangojs``
|
|
domain is only used for JavaScript translation catalogs to make sure
|
|
that those are as small as possible.
|
|
* Django doesn't use ``xgettext`` alone. It uses Python wrappers around
|
|
``xgettext`` and ``msgfmt``. This is mostly for convenience.
|
|
|
|
``gettext`` on Windows
|
|
======================
|
|
|
|
This is only needed for people who either want to extract message IDs or compile
|
|
message files (``.po``). Translation work itself just involves editing existing
|
|
files of this type, but if you want to create your own message files, or want to
|
|
test or compile a changed message file, you will need the ``gettext`` utilities:
|
|
|
|
* Download the following zip files from
|
|
http://sourceforge.net/projects/gettext
|
|
|
|
* ``gettext-runtime-X.bin.woe32.zip``
|
|
* ``gettext-tools-X.bin.woe32.zip``
|
|
* ``libiconv-X.bin.woe32.zip``
|
|
|
|
* Extract the 3 files in the same folder (i.e. ``C:\Program
|
|
Files\gettext-utils``)
|
|
|
|
* Update the system PATH:
|
|
|
|
* ``Control Panel > System > Advanced > Environment Variables``
|
|
* In the ``System variables`` list, click ``Path``, click ``Edit``
|
|
* Add ``;C:\Program Files\gettext-utils\bin`` at the end of the
|
|
``Variable value`` field
|
|
|
|
You may also use ``gettext`` binaries you have obtained elsewhere, so long as
|
|
the ``xgettext --version`` command works properly. Some version 0.14.4 binaries
|
|
have been found to not support this command. Do not attempt to use Django
|
|
translation utilities with a ``gettext`` package if the command ``xgettext
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--version`` entered at a Windows command prompt causes a popup window saying
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"xgettext.exe has generated errors and will be closed by Windows".
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