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Fixed #10260 - Refactored internationalization documentation. Thanks, Ramiro Morales. 

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12440 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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Jannis Leidel 2010-02-16 12:12:53 +00:00
parent 9b630a0857
commit f93f056c32
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2
django/conf/global_settings.py
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@ -306,7 +306,7 @@ YEAR_MONTH_FORMAT = 'F Y'
# http://docs.djangoproject.com/en/dev/ref/templates/builtins/#now
MONTH_DAY_FORMAT = 'F j'
# Default shortformatting for date objects. See all available format strings here:
# Default short formatting for date objects. See all available format strings here:
# http://docs.djangoproject.com/en/dev/ref/templates/builtins/#now
SHORT_DATE_FORMAT = 'm/d/Y'

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@ -0,0 +1,72 @@
.. _howto-i18n:
.. _using-translations-in-your-own-projects:
===============================================
Using internationalization in your own projects
===============================================
At runtime, 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``.
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
:ref:`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.

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docs/howto/index.txt
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@ -20,6 +20,7 @@ you quickly accomplish common tasks.
deployment/index
error-reporting
initial-data
i18n
jython
legacy-databases
outputting-csv

19
docs/internals/contributing.txt
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@ -402,15 +402,18 @@ translated, here's what to do:
* Join the `Django i18n mailing list`_ and introduce yourself.
* Make sure you read the notes about :ref:`specialties-of-django-i18n`.
* Create translations using the methods described in the
:ref:`i18n documentation <topics-i18n>`. For this you will use the
``django-admin.py makemessages`` tool. In this particular case it should
be run from the top-level ``django`` directory of the Django source tree.
:ref:`localization documentation <topics-i18n-localization>`. For this
you will use the ``django-admin.py makemessages`` tool. In this
particular case it should be run from the top-level ``django`` directory
of the Django source tree.
The script runs over the entire Django source tree and pulls out all
strings marked for translation. It creates (or updates) a message file in
the directory ``conf/locale`` (for example for ``pt-BR``, the file will be
``conf/locale/pt-br/LC_MESSAGES/django.po``).
the directory ``conf/locale`` (for example for ``pt_BR``, the file will be
``conf/locale/pt_BR/LC_MESSAGES/django.po``).
* Make sure that ``django-admin.py compilemessages -l <lang>`` runs without
producing any warnings.
@ -419,7 +422,11 @@ translated, here's what to do:
``-d djangojs`` command line option to the ``django-admin.py``
invocations).
* Create a diff of the ``.po`` file(s) against the current Subversion trunk.
* Optionally, review and update the ``conf/locale/<locale>/formats.py``
file to describe the date, time and numbers formatting particularities of
your locale. See :ref:`format-localization` for details.
* Create a diff against the current Subversion trunk.
* Open a ticket in Django's ticket system, set its ``Component`` field to
``Translations``, and attach the patch to it.

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docs/ref/settings.txt
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@ -883,8 +883,8 @@ LANGUAGE_CODE
Default: ``'en-us'``
A string representing the language code for this installation. This should be in
standard language format. For example, U.S. English is ``"en-us"``. See
:ref:`topics-i18n`.
standard :term:`language format<language code>`. For example, U.S. English is
``"en-us"``. See :ref:`topics-i18n`.
.. setting:: LANGUAGE_COOKIE_NAME
@ -911,9 +911,11 @@ see the current list of translated languages by looking in
.. _online source: http://code.djangoproject.com/browser/django/trunk/django/conf/global_settings.py
The list is a tuple of two-tuples in the format (language code, language
name) -- for example, ``('ja', 'Japanese')``. This specifies which languages
are available for language selection. See :ref:`topics-i18n`.
The list is a tuple of two-tuples in the format ``(language code, language
name)``, the ``language code`` part should be a
:term:`language name<language code>` -- for example, ``('ja', 'Japanese')``.
This specifies which languages are available for language selection. See
:ref:`topics-i18n`.
Generally, the default value should suffice. Only set this setting if you want
to restrict language selection to a subset of the Django-provided languages.
@ -948,7 +950,7 @@ LOCALE_PATHS
Default: ``()`` (Empty tuple)
A tuple of directories where Django looks for translation files.
See :ref:`translations-in-your-own-projects`.
See :ref:`using-translations-in-your-own-projects`.
.. setting:: LOGIN_REDIRECT_URL

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docs/releases/1.2.txt
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@ -516,6 +516,19 @@ documentation <ref-contrib-syndication>`.
.. _RSS best practices: http://www.rssboard.org/rss-profile
Technical message IDs
---------------------
Up to version 1.1 Django used :ref:`technical message IDs<technical-messages>`
to provide localizers the possibility to translate date and time formats. They
were translatable :term:`translation strings <translation string>` that could
be recognized because they were all upper case (for example
``DATETIME_FORMAT``, ``DATE_FORMAT``, ``TIME_FORMAT``). They have been
deprecated in favor of the new :ref:`Format localization
<format-localization>` infrastructure that allows localizers to specify that
information in a ``formats.py`` file in the corresponding
``django/conf/locale/<locale name>/`` directory.
What's new in Django 1.2
========================
@ -577,7 +590,7 @@ added support for comparison operators. No longer will you have to type:
.. code-block:: html+django
{% ifnotequal a b %}
...
...
{% endifnotequal %}
You can now do this:
@ -585,7 +598,7 @@ You can now do this:
.. code-block:: html+django
{% if a != b %}
...
...
{% endif %}
There's really no reason to use ``{% ifequal %}`` or ``{% ifnotequal %}``

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@ -0,0 +1,195 @@
.. _topics-i18n-deployment:
==========================
Deployment of translations
==========================
If you don't need internationalization
======================================
Django's internationalization hooks are on by default, and that means there's a
bit of i18n-related overhead in certain places of the framework. If you don't
use internationalization, you should take the two seconds to set
:setting:`USE_I18N = False <USE_I18N>` in your settings file. If
:setting:`USE_I18N` is set to ``False``, then Django will make some
optimizations so as not to load the internationalization machinery.
You'll probably also want to remove ``'django.core.context_processors.i18n'``
from your ``TEMPLATE_CONTEXT_PROCESSORS`` setting.
.. note::
There is also an independent but related :setting:`USE_L10N` setting that
controls if Django should implement format localization.
If :setting:`USE_L10N` is set to ``True``, Django will handle numbers times,
and dates in the format of the current locale. That includes representation
of these field types on templates and allowed input formats for dates,
times on model forms.
See :ref:`format-localization` for more details.
If you do need internationalization
===================================
.. _how-django-discovers-language-preference:
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 it, 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 :term:`language format<language code>`, 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 a basic
one as described in the :ref:`Locale restrictions<locale-restrictions>`
note.
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
How Django discovers translations
---------------------------------
As described in :ref:`using-translations-in-your-own-projects`,
at runtime, 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``.
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.

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@ -0,0 +1,115 @@
.. _topics-i18n:
=====================================
Internationalization and localization
=====================================
Overview
========
Django has full support for internationalization of text in code and
templates, and format localization of dates and numbers. Here's how it works.
Essentially, Django does two things:
* It allows developers and template authors to specify which parts of
their apps should be translatable.
* It uses these hooks to translate Web apps for particular users according
to their language preferences.
The complete process can be seen as divided in three stages. It is also possible
to identify an identical number of roles with very well defined responsabilities
associated with each of these tasks (although it's perfectly normal if you
find yourself performing more than one of these roles):
* For applicacion authors wishing to make sure their Django apps can be
used in different locales: :ref:`topics-i18n-internationalization`.
* For translators wanting to translate Django apps: :ref:`topics-i18n-localization`.
* For system administrators/final users setting up internationalized apps or
developers integrating third party apps: :ref:`topics-i18n-deployment`.
.. toctree::
:hidden:
:maxdepth: 1
internationalization
localization
deployment
.. _ seealso::
For more general information about the topic, see the `GNU gettext documentation`_
and the `Wikipedia article`_.
.. _GNU gettext documentation: http://www.gnu.org/software/gettext/manual/gettext.html#Concepts
.. _Wikipedia article: http://en.wikipedia.org/wiki/Internationalization_and_localization
Glossary
========
First lets define some terms that will help us to handle a common language:
.. glossary::
locale name
A locale name, either a language specification of the form ``ll`` or a
combined language and country specification of the form ``ll_CC``.
Examples: ``it``, ``de_AT``, ``es``, ``pt_BR``. Note the underscore in
some of them and the case of the part located to its right.
language code
Represents the name of a language. Browsers send the names of the
languages they accept in the ``Accept-Language`` HTTP header using this
format. Examples: ``it``, ``de-at``, ``es``, ``pt-br``. Note the ``-``
separator.
message file
A message file is a plain-text file, representing a single language,
that contains all available :term:`translation strings
<translation string>` and how they should be represented in the given
language. Message files have a ``.po`` file extension.
translation string
A literal that can be translated.
.. _specialties-of-django-i18n:
Specialties of Django translation
=================================
Django's translation machinery uses the standard ``gettext`` module that comes
with Python. 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.
.. _technical-messages:
Django technical message IDs
----------------------------
.. versionchanged:: 1.2
Starting with Django 1.2, technical message IDs are being replaced by :ref:`format-localization`
Django uses technical message IDs to translate date formats and time formats.
Technical message IDs are :term:`translation strings <translation string>` and
can be easily recognized; they're all upper case. You don't translate the
message ID as with other translation strings, you provide the correct local
variant on the provided English value. The format is identical to the format
strings used by the ``now`` template tag.
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. A Django
contributor localizing it to Spanish probably would provide a ``"j N Y P"``
"translation" for it in the relevant ``django.po`` file::
msgid "DATETIME_FORMAT"
msgstr "j N Y P"

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@ -0,0 +1,578 @@
.. _topics-i18n-internationalization:
====================
Internationalization
====================
Overview
========
The goal of internationalization is to allow a single Web application to offer
its content and functionality in multiple languages and locales.
For text translations, you, the Django developer, can accomplish this goal by
adding a minimal amount of hooks to your Python and templates. These hooks
are called **translation strings**. They tell Django: "This text should be
translated into the end user's language, if a translation for this text is
available in that language." It's your responsibility to mark translatable
strings; the system can only translate strings it knows about.
Django takes care of using these hooks to translate Web apps, on the fly,
according to users' language preferences.
Specifying translation strings: In Python code
==============================================
Standard translation
--------------------
Specify a translation string by using the function ``ugettext()``. It's
convention to import this as a shorter alias, ``_``, to save typing.
.. note::
Python's standard library ``gettext`` module installs ``_()`` into the
global namespace, as an alias for ``gettext()``. In Django, we have chosen
not to follow this practice, for a couple of reasons:
1. For international character set (Unicode) support, ``ugettext()`` is
more useful than ``gettext()``. Sometimes, you should be using
``ugettext_lazy()`` as the default translation method for a particular
file. Without ``_()`` in the global namespace, the developer has to
think about which is the most appropriate translation function.
2. The underscore character (``_``) is used to represent "the previous
result" in Python's interactive shell and doctest tests. Installing a
global ``_()`` function causes interference. Explicitly importing
``ugettext()`` as ``_()`` avoids this problem.
.. highlightlang:: python
In this example, the text ``"Welcome to my site."`` is marked as a translation
string::
from django.utils.translation import ugettext as _
def my_view(request):
output = _("Welcome to my site.")
return HttpResponse(output)
Obviously, you could code this without using the alias. This example is
identical to the previous one::
from django.utils.translation import ugettext
def my_view(request):
output = ugettext("Welcome to my site.")
return HttpResponse(output)
Translation works on computed values. This example is identical to the previous
two::
def my_view(request):
words = ['Welcome', 'to', 'my', 'site.']
output = _(' '.join(words))
return HttpResponse(output)
Translation works on variables. Again, here's an identical example::
def my_view(request):
sentence = 'Welcome to my site.'
output = _(sentence)
return HttpResponse(output)
(The caveat with using variables or computed values, as in the previous two
examples, is that Django's translation-string-detecting utility,
``django-admin.py makemessages``, won't be able to find these strings. More on
``makemessages`` later.)
The strings you pass to ``_()`` or ``ugettext()`` can take placeholders,
specified with Python's standard named-string interpolation syntax. Example::
def my_view(request, m, d):
output = _('Today is %(month)s, %(day)s.') % {'month': m, 'day': d}
return HttpResponse(output)
This technique lets language-specific translations reorder the placeholder
text. For example, an English translation may be ``"Today is November, 26."``,
while a Spanish translation may be ``"Hoy es 26 de Noviembre."`` -- with the
placeholders (the month and the day) with their positions swapped.
For this reason, you should use named-string interpolation (e.g., ``%(day)s``)
instead of positional interpolation (e.g., ``%s`` or ``%d``) whenever you
have more than a single parameter. If you used positional interpolation,
translations wouldn't be able to reorder placeholder text.
Marking strings as no-op
------------------------
Use the function ``django.utils.translation.ugettext_noop()`` to mark a string
as a translation string without translating it. The string is later translated
from a variable.
Use this if you have constant strings that should be stored in the source
language because they are exchanged over systems or users -- such as strings in
a database -- but should be translated at the last possible point in time, such
as when the string is presented to the user.
Pluralization
-------------
Use the function ``django.utils.translation.ungettext()`` to specify pluralized
messages.
``ungettext`` takes three arguments: the singular translation string, the plural
translation string and the number of objects.
This function is useful when you need your Django application to be localizable
to languages where the number and complexity of `plural forms
<http://www.gnu.org/software/gettext/manual/gettext.html#Plural-forms>`_ is
greater than the two forms used in English ('object' for the singular and
'objects' for all the cases where ``count`` is different from zero, irrespective
of its value.)
For example::
from django.utils.translation import ungettext
def hello_world(request, count):
page = ungettext('there is %(count)d object', 'there are %(count)d objects', count) % {
'count': count,
}
return HttpResponse(page)
In this example the number of objects is passed to the translation languages as
the ``count`` variable.
Lets see a slightly more complex usage example::
from django.utils.translation import ungettext
count = Report.objects.count()
if count == 1:
name = Report._meta.verbose_name
else:
name = Report._meta.verbose_name_plural
text = ungettext(
'There is %(count)d %(name)s available.',
'There are %(count)d %(name)s available.',
count
) % {
'count': count,
'name': name
}
Here we reuse localizable, hopefully already translated literals (contained in
the ``verbose_name`` and ``verbose_name_plural`` model ``Meta`` options) for
other parts of the sentence so all of it is consistently based on the
cardinality of the elements at play.
.. _pluralization-var-notes:
.. note::
When using this technique, make sure you use a single name for every
extrapolated variable included in the literal. In the example above note how
we used the ``name`` Python variable in both translation strings. This
example would fail::
from django.utils.translation import ungettext
from myapp.models import Report
count = Report.objects.count()
d = {
'count': count,
'name': Report._meta.verbose_name
'plural_name': Report._meta.verbose_name_plural
}
text = ungettext(
'There is %(count)d %(name)s available.',
'There are %(count)d %(plural_name)s available.',
count
) % d
You would get a ``a format specification for argument 'name', as in
'msgstr[0]', doesn't exist in 'msgid'`` error when running
``django-admin.py compilemessages`` or a ``KeyError`` Python exception at
runtime.
.. _lazy-translations:
Lazy translation
----------------
Use the function ``django.utils.translation.ugettext_lazy()`` to translate
strings lazily -- when the value is accessed rather than when the
``ugettext_lazy()`` function is called.
For example, to translate a model's ``help_text``, do the following::
from django.utils.translation import ugettext_lazy
class MyThing(models.Model):
name = models.CharField(help_text=ugettext_lazy('This is the help text'))
In this example, ``ugettext_lazy()`` stores a lazy reference to the string --
not the actual translation. The translation itself will be done when the string
is used in a string context, such as template rendering on the Django admin
site.
The result of a ``ugettext_lazy()`` call can be used wherever you would use a
unicode string (an object with type ``unicode``) in Python. If you try to use
it where a bytestring (a ``str`` object) is expected, things will not work as
expected, since a ``ugettext_lazy()`` object doesn't know how to convert
itself to a bytestring. You can't use a unicode string inside a bytestring,
either, so this is consistent with normal Python behavior. For example::
# This is fine: putting a unicode proxy into a unicode string.
u"Hello %s" % ugettext_lazy("people")
# This will not work, since you cannot insert a unicode object
# into a bytestring (nor can you insert our unicode proxy there)
"Hello %s" % ugettext_lazy("people")
If you ever see output that looks like ``"hello
<django.utils.functional...>"``, you have tried to insert the result of
``ugettext_lazy()`` into a bytestring. That's a bug in your code.
If you don't like the verbose name ``ugettext_lazy``, you can just alias it as
``_`` (underscore), like so::
from django.utils.translation import ugettext_lazy as _
class MyThing(models.Model):
name = models.CharField(help_text=_('This is the help text'))
Always use lazy translations in :ref:`Django models <topics-db-models>`.
Field names and table names should be marked for translation (otherwise, they
won't be translated in the admin interface). This means writing explicit
``verbose_name`` and ``verbose_name_plural`` options in the ``Meta`` class,
though, rather than relying on Django's default determination of
``verbose_name`` and ``verbose_name_plural`` by looking at the model's class
name::
from django.utils.translation import ugettext_lazy as _
class MyThing(models.Model):
name = models.CharField(_('name'), help_text=_('This is the help text'))
class Meta:
verbose_name = _('my thing')
verbose_name_plural = _('mythings')
Working with lazy translation objects
-------------------------------------
.. highlightlang:: python
Using ``ugettext_lazy()`` and ``ungettext_lazy()`` to mark strings in models
and utility functions is a common operation. When you're working with these
objects elsewhere in your code, you should ensure that you don't accidentally
convert them to strings, because they should be converted as late as possible
(so that the correct locale is in effect). This necessitates the use of a
couple of helper functions.
Joining strings: string_concat()
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Standard Python string joins (``''.join([...])``) will not work on lists
containing lazy translation objects. Instead, you can use
``django.utils.translation.string_concat()``, which creates a lazy object that
concatenates its contents *and* converts them to strings only when the result
is included in a string. For example::
from django.utils.translation import string_concat
...
name = ugettext_lazy(u'John Lennon')
instrument = ugettext_lazy(u'guitar')
result = string_concat([name, ': ', instrument])
In this case, the lazy translations in ``result`` will only be converted to
strings when ``result`` itself is used in a string (usually at template
rendering time).
The allow_lazy() decorator
~~~~~~~~~~~~~~~~~~~~~~~~~~
Django offers many utility functions (particularly in ``django.utils``) that
take a string as their first argument and do something to that string. These
functions are used by template filters as well as directly in other code.
If you write your own similar functions and deal with translations, you'll
face the problem of what to do when the first argument is a lazy translation
object. You don't want to convert it to a string immediately, because you might
be using this function outside of a view (and hence the current thread's locale
setting will not be correct).
For cases like this, use the ``django.utils.functional.allow_lazy()``
decorator. It modifies the function so that *if* it's called with a lazy
translation as the first argument, the function evaluation is delayed until it
needs to be converted to a string.
For example::
from django.utils.functional import allow_lazy
def fancy_utility_function(s, ...):
# Do some conversion on string 's'
...
fancy_utility_function = allow_lazy(fancy_utility_function, unicode)
The ``allow_lazy()`` decorator takes, in addition to the function to decorate,
a number of extra arguments (``*args``) specifying the type(s) that the
original function can return. Usually, it's enough to include ``unicode`` here
and ensure that your function returns only Unicode strings.
Using this decorator means you can write your function and assume that the
input is a proper string, then add support for lazy translation objects at the
end.
Specifying translation strings: In template code
================================================
.. highlightlang:: html+django
Translations in :ref:`Django templates <topics-templates>` uses two template
tags and a slightly different syntax than in Python code. To give your template
access to these tags, put ``{% load i18n %}`` toward the top of your template.
The ``{% trans %}`` template tag translates either a constant string
(enclosed in single or double quotes) or variable content::
<title>{% trans "This is the title." %}</title>
<title>{% trans myvar %}</title>
If the ``noop`` option is present, variable lookup still takes place but the
translation is skipped. This is useful when "stubbing out" content that will
require translation in the future::
<title>{% trans "myvar" noop %}</title>
Internally, inline translations use an ``ugettext`` call.
It's not possible to mix a template variable inside a string within ``{% trans
%}``. If your translations require strings with variables (placeholders), use
``{% blocktrans %}``::
{% blocktrans %}This string will have {{ value }} inside.{% endblocktrans %}
To translate a template expression -- say, using template filters -- you need
to bind the expression to a local variable for use within the translation
block::
{% blocktrans with value|filter as myvar %}
This will have {{ myvar }} inside.
{% endblocktrans %}
If you need to bind more than one expression inside a ``blocktrans`` tag,
separate the pieces with ``and``::
{% blocktrans with book|title as book_t and author|title as author_t %}
This is {{ book_t }} by {{ author_t }}
{% endblocktrans %}
To pluralize, specify both the singular and plural forms with the
``{% plural %}`` tag, which appears within ``{% blocktrans %}`` and
``{% endblocktrans %}``. Example::
{% blocktrans count list|length as counter %}
There is only one {{ name }} object.
{% plural %}
There are {{ counter }} {{ name }} objects.
{% endblocktrans %}
When you use the pluralization feature and bind additional values to local
variables apart from the counter value that selects the translated literal to be
used, have in mind that the ``blocktrans`` construct is internally converted
to an ``ungettext`` call. This means the same :ref:`notes regarding ungettext
variables <pluralization-var-notes>` apply.
Each ``RequestContext`` has access to three translation-specific variables:
* ``LANGUAGES`` is a list of tuples in which the first element is the
:term:`language code` and the second is the language name (translated into
the currently active locale).
* ``LANGUAGE_CODE`` is the current user's preferred language, as a string.
Example: ``en-us``. (See :ref:`how-django-discovers-language-preference`.)
* ``LANGUAGE_BIDI`` is the current locale's direction. If True, it's a
right-to-left language, e.g.: Hebrew, Arabic. If False it's a
left-to-right language, e.g.: English, French, German etc.
If you don't use the ``RequestContext`` extension, you can get those values with
three tags::
{% get_current_language as LANGUAGE_CODE %}
{% get_available_languages as LANGUAGES %}
{% get_current_language_bidi as LANGUAGE_BIDI %}
These tags also require a ``{% load i18n %}``.
Translation hooks are also available within any template block tag that accepts
constant strings. In those cases, just use ``_()`` syntax to specify a
translation string::
{% some_special_tag _("Page not found") value|yesno:_("yes,no") %}
In this case, both the tag and the filter will see the already-translated
string, so they don't need to be aware of translations.
.. note::
In this example, the translation infrastructure will be passed the string
``"yes,no"``, not the individual strings ``"yes"`` and ``"no"``. The
translated string will need to contain the comma so that the filter
parsing code knows how to split up the arguments. For example, a German
translator might translate the string ``"yes,no"`` as ``"ja,nein"``
(keeping the comma intact).
.. _Django templates: ../templates_python/
Specifying translation strings: In JavaScript code
==================================================
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={% url django.views.i18n.javascript_catalog %}"></script>
This uses reverse URL lookup to find the URL of the JavaScript catalog view.
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).
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.)
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>

294
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@ -0,0 +1,294 @@
.. _topics-i18n-localization:
============
Localization
============
This document covers two localization-related topics: `Creating language
files`_ and `locale aware date, time and numbers input/output in forms`_
.. _`Creating language files`: how-to-create-language-files_
.. _`locale aware date, time and numbers input/output in forms`: format-localization_
.. seealso::
The :ref:`howto-i18n` document included with the Django HOW-TO documents collection.
.. _how-to-create-language-files:
How to create language files
============================
Once the string literals of an application have been tagged for later
translation, the translation themselves need to be written (or obtained). Here's
how that works.
.. _locale-restrictions:
.. admonition:: Locale restrictions
Django does not support localizing your application into a locale for which
Django itself has not been translated. In this case, it will ignore your
translation files. If you were to try this and Django supported it, you
would inevitably see a mixture of translated strings (from your application)
and English strings (from Django itself). If you want to support a locale
for your application that is not already part of Django, you'll need to make
at least a minimal translation of the Django core.
A good starting point is to copy the Django English ``.po`` file and to
translate at least some :term:`translation strings <translation string>`.
Message files
-------------
The first step is to create a :term:`message file` for a new language. A message
file is a plain-text file, representing a single language, that contains all
available translation strings and how they should be represented in the given
language. Message files have a ``.po`` file extension.
Django comes with a tool, ``django-admin.py makemessages``, that automates the
creation and upkeep of these files.
.. admonition:: A note to Django veterans
The old tool ``bin/make-messages.py`` has been moved to the command
``django-admin.py makemessages`` to provide consistency throughout Django.
.. admonition:: Gettext utilities
The ``makemessages`` command (and ``compilemessages`` discussed later) use
commands from the GNU gettext toolset: ``xgetetxt``, ``msgfmt``,
``msgmerge`` and ``msguniq``.
.. versionchanged:: 1.2
The minimum version of the ``gettext`` utilities supported is 0.15.
To create or update a message file, run this command::
django-admin.py makemessages -l de
...where ``de`` is the language code for the message file you want to create.
The language code, in this case, is in :term:`locale format<locale name>`. For
example, it's ``pt_BR`` for Brazilian Portuguese and ``de_AT`` for Austrian
German.
The script should be run from one of two places:
* The root directory of your Django project.
* The root directory of your Django app.
Th script runs over your project source tree or your application source tree and
pulls out all strings marked for translation. It creates (or updates) a message
file in the directory ``locale/LANG/LC_MESSAGES``. In the ``de`` example, the
file will be ``locale/de/LC_MESSAGES/django.po``.
By default ``django-admin.py makemessages`` examines every file that has the
``.html`` file extension. In case you want to override that default, use the
``--extension`` or ``-e`` option to specify the file extensions to examine::
django-admin.py makemessages -l de -e txt
Separate multiple extensions with commas and/or use ``-e`` or ``--extension``
multiple times::
django-admin.py makemessages -l de -e html,txt -e xml
When :ref:`creating message files from JavaScript source code
<creating-message-files-from-js-code>` you need to use the special 'djangojs'
domain, **not** ``-e js``.
.. admonition:: No gettext?
If you don't have the ``gettext`` utilities installed, ``django-admin.py
makemessages`` will create empty files. If that's the case, either install
the ``gettext`` utilities or just copy the English message file
(``locale/en/LC_MESSAGES/django.po``) if available and use it as a starting
point; it's just an empty translation file.
.. admonition:: Working on Windows?
If you're using Windows and need to install the GNU gettext utilities so
``django-admin makemessages`` works see :ref:`gettext_on_windows` for more
information.
The format of ``.po`` files is straightforward. Each ``.po`` file contains a
small bit of metadata, such as the translation maintainer's contact
information, but the bulk of the file is a list of **messages** -- simple
mappings between translation strings and the actual translated text for the
particular language.
For example, if your Django app contained a translation string for the text
``"Welcome to my site."``, like so::
_("Welcome to my site.")
...then ``django-admin.py makemessages`` will have created a ``.po`` file
containing the following snippet -- a message::
#: path/to/python/module.py:23
msgid "Welcome to my site."
msgstr ""
A quick explanation:
* ``msgid`` is the translation string, which appears in the source. Don't
change it.
* ``msgstr`` is where you put the language-specific translation. It starts
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 located 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 :ref:`gettext_on_windows` for more
information.
.. _creating-message-files-from-js-code:
Creating message files from JavaScript source code
==================================================
You create and update the message files the same way as the other Django message
files -- 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 message file for JavaScript for German.
After updating message files, just run ``django-admin.py compilemessages``
the same way as you do with normal Django message files.
.. _gettext_on_windows:
``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 the GNOME servers
http://ftp.gnome.org/pub/gnome/binaries/win32/dependencies/ or from one
of its mirrors_
* ``gettext-runtime-X.zip``
* ``gettext-tools-X.zip``
``X`` is the version number, we are requiring ``0.15`` or higher.
* Extract the contents of the ``bin\`` directories in both files to the
same folder on your system (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.
.. _mirrors: http://ftp.gnome.org/pub/GNOME/MIRRORS
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
--version`` entered at a Windows command prompt causes a popup window saying
"xgettext.exe has generated errors and will be closed by Windows".
.. _format-localization:
Format localization
===================
Django's formatting system is disabled by default. To enable it, it's necessay
to set :setting:`USE_L10N = True <USE_L10N>` in your settings file.
When using Django's formatting system, dates and numbers on templates will be
displayed using the format specified for the current locale. Two users
accessing the same content, but in different language, will see date and
number fields formatted in different ways, depending on the format for their
current locale.
Django will also use localized formats when parsing data in forms. That means
Django uses different formats for different locales when guessing the format
used by the user when inputting data on forms. Note that Django uses different
formats for displaying data, and for parsing it.
Creating custom format files
----------------------------
Django provides format definitions for many locales, but sometimes you might
want to create your own, because a format files doesn't exist for your locale,
or because you want to overwrite some of the values.
To use custom formats, first thing to do, is to specify the path where you'll
place format files. To do that, just set your :setting:`FORMAT_MODULE_PATH`
setting to the the path (in the format ``'foo.bar.baz``) where format files
will exists.
Files are not placed directly in this directory, but in a directory named as
the locale, and must be named ``formats.py``.
To customize the English formats, a structure like this would be needed::
mysite/
formats/
__init__.py
en/
__init__.py
formats.py
where :file:`formats.py` contains custom format definitions. For example::
THOUSAND_SEPARATOR = ' '
to use a space as a thousand separator, instead of the default for English,
a comma.

2
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@ -21,7 +21,7 @@ Introductions to all the key parts of Django you'll need to know:
cache
conditional-view-processing
email
i18n
i18n/index
pagination
serialization
settings