In order to make a Django project translatable, you have to add a minimal number of hooks to your Python code 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 then provides utilities to extract the translation strings into a message file. This file is a convenient way for translators to provide the equivalent of the translation strings in the target language. Once the translators have filled in the message file, it must be compiled. This process relies on the GNU gettext toolset.
Once this is done, Django takes care of translating web apps on the fly in each available language, according to users’ language preferences.
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
USE_I18N = False in your settings file. Then Django will
make some optimizations so as not to load the internationalization machinery.
Note
Make sure you’ve activated translation for your project (the fastest way is
to check if MIDDLEWARE includes
django.middleware.locale.LocaleMiddleware). If you haven’t yet,
see How Django discovers language preference.
Specify a translation string by using the function
gettext(). 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:
Sometimes, you should use gettext_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.
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
gettext() as _() avoids this problem.
What functions may be aliased as _?
Because of how xgettext (used by makemessages) works, only
functions that take a single string argument can be imported as _:
In this example, the text "Welcome to my site." is marked as a translation
string:
from django.http import HttpResponse
from django.utils.translation import gettext as _
def my_view(request):
output = _("Welcome to my site.")
return HttpResponse(output)
You could code this without using the alias. This example is identical to the previous one:
from django.http import HttpResponse
from django.utils.translation import gettext
def my_view(request):
output = gettext("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 makemessages, won’t be able to find
these strings. More on makemessages later.)
The strings you pass to _() or gettext() 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
month and the day placeholders 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.
Since string extraction is done by the xgettext command, only syntaxes
supported by gettext are supported by Django. In particular, Python
f-strings are not yet supported by xgettext, and
JavaScript template strings need gettext 0.21+.
Use the function django.utils.translation.gettext_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.
Use the function django.utils.translation.ngettext() to specify
pluralized messages.
ngettext() 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 is
greater than the two forms used in English (‘object’ for the singular and
‘objects’ for all the cases where count is different from one, irrespective
of its value.)
For example:
from django.http import HttpResponse
from django.utils.translation import ngettext
def hello_world(request, count):
page = ngettext(
"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.
Note that pluralization is complicated and works differently in each language.
Comparing count to 1 isn’t always the correct rule. This code looks
sophisticated, but will produce incorrect results for some languages:
from django.utils.translation import ngettext
from myapp.models import Report
count = Report.objects.count()
if count == 1:
name = Report._meta.verbose_name
else:
name = Report._meta.verbose_name_plural
text = ngettext(
"There is %(count)d %(name)s available.",
"There are %(count)d %(name)s available.",
count,
) % {"count": count, "name": name}
Don’t try to implement your own singular-or-plural logic; it won’t be correct. In a case like this, consider something like the following:
text = ngettext(
"There is %(count)d %(name)s object available.",
"There are %(count)d %(name)s objects available.",
count,
) % {
"count": count,
"name": Report._meta.verbose_name,
}
Note
When using ngettext(), make sure you use a single name for every
extrapolated variable included in the literal. In the examples above, note
how we used the name Python variable in both translation strings. This
example, besides being incorrect in some languages as noted above, would
fail:
text = ngettext(
"There is %(count)d %(name)s available.",
"There are %(count)d %(plural_name)s available.",
count,
) % {
"count": Report.objects.count(),
"name": Report._meta.verbose_name,
"plural_name": Report._meta.verbose_name_plural,
}
You would get an error when running django-admin
compilemessages:
a format specification for argument 'name', as in 'msgstr[0]', doesn't exist in 'msgid'
Sometimes words have several meanings, such as "May" in English, which
refers to a month name and to a verb. To enable translators to translate
these words correctly in different contexts, you can use the
django.utils.translation.pgettext() function, or the
django.utils.translation.npgettext() function if the string needs
pluralization. Both take a context string as the first variable.
In the resulting .po file, the string will then appear as often as there are
different contextual markers for the same string (the context will appear on the
msgctxt line), allowing the translator to give a different translation for
each of them.
For example:
from django.utils.translation import pgettext
month = pgettext("month name", "May")
or:
from django.db import models
from django.utils.translation import pgettext_lazy
class MyThing(models.Model):
name = models.CharField(
help_text=pgettext_lazy("help text for MyThing model", "This is the help text")
)
will appear in the .po file as:
msgctxt "month name"
msgid "May"
msgstr ""
Contextual markers are also supported by the translate and
blocktranslate template tags.
Use the lazy versions of translation functions in
django.utils.translation (easily recognizable by the lazy suffix in
their names) to translate strings lazily – when the value is accessed rather
than when they’re called.
These functions store 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 in template rendering.
This is essential when calls to these functions are located in code paths that are executed at module load time.
This is something that can easily happen when defining models, forms and model forms, because Django implements these such that their fields are actually class-level attributes. For that reason, make sure to use lazy translations in the following cases:
verbose_name and help_text option values¶For example, to translate the help text of the name field in the following model, do the following:
from django.db import models
from django.utils.translation import gettext_lazy as _
class MyThing(models.Model):
name = models.CharField(help_text=_("This is the help text"))
You can mark names of ForeignKey,
ManyToManyField or
OneToOneField relationship as translatable by using
their verbose_name options:
class MyThing(models.Model):
kind = models.ForeignKey(
ThingKind,
on_delete=models.CASCADE,
related_name="kinds",
verbose_name=_("kind"),
)
Just like you would do in verbose_name you
should provide a lowercase verbose name text for the relation as Django will
automatically titlecase it when required.
It is recommended to always provide explicit
verbose_name and
verbose_name_plural options rather than
relying on the fallback English-centric and somewhat naïve determination of
verbose names Django performs by looking at the model’s class name:
from django.db import models
from django.utils.translation import gettext_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 = _("my things")
description argument to the @display decorator¶For model methods, you can provide translations to Django and the admin site
with the description argument to the display()
decorator:
from django.contrib import admin
from django.db import models
from django.utils.translation import gettext_lazy as _
class MyThing(models.Model):
kind = models.ForeignKey(
ThingKind,
on_delete=models.CASCADE,
related_name="kinds",
verbose_name=_("kind"),
)
@admin.display(description=_("Is it a mouse?"))
def is_mouse(self):
return self.kind.type == MOUSE_TYPE
The result of a gettext_lazy() call can be used wherever you would use a
string (a str object) in other Django code, but it may not work with
arbitrary Python code. For example, the following won’t work because the
requests library doesn’t handle gettext_lazy objects:
body = gettext_lazy("I \u2764 Django") # (Unicode :heart:)
requests.post("https://example.com/send", data={"body": body})
You can avoid such problems by casting gettext_lazy() objects to text
strings before passing them to non-Django code:
requests.post("https://example.com/send", data={"body": str(body)})
If you don’t like the long gettext_lazy name, you can alias it as _
(underscore), like so:
from django.db import models
from django.utils.translation import gettext_lazy as _
class MyThing(models.Model):
name = models.CharField(help_text=_("This is the help text"))
Using gettext_lazy() and ngettext_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 the
helper function described next.
When using lazy translation for a plural string (n[p]gettext_lazy), you
generally don’t know the number argument at the time of the string
definition. Therefore, you are authorized to pass a key name instead of an
integer as the number argument. Then number will be looked up in the
dictionary under that key during string interpolation. Here’s example:
from django import forms
from django.core.exceptions import ValidationError
from django.utils.translation import ngettext_lazy
class MyForm(forms.Form):
error_message = ngettext_lazy(
"You only provided %(num)d argument",
"You only provided %(num)d arguments",
"num",
)
def clean(self):
# ...
if error:
raise ValidationError(self.error_message % {"num": number})
If the string contains exactly one unnamed placeholder, you can interpolate
directly with the number argument:
class MyForm(forms.Form):
error_message = ngettext_lazy(
"You provided %d argument",
"You provided %d arguments",
)
def clean(self):
# ...
if error:
raise ValidationError(self.error_message % number)
format_lazy()¶Python’s str.format() method will not work when either the
format_string or any of the arguments to str.format()
contains lazy translation objects. Instead, you can use
django.utils.text.format_lazy(), which creates a lazy object
that runs the str.format() method only when the result is included
in a string. For example:
from django.utils.text import format_lazy
from django.utils.translation import gettext_lazy
...
name = gettext_lazy("John Lennon")
instrument = gettext_lazy("guitar")
result = format_lazy("{name}: {instrument}", name=name, instrument=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).
For any other case where you would like to delay the translation, but have to pass the translatable string as argument to another function, you can wrap this function inside a lazy call yourself. For example:
from django.utils.functional import lazy
from django.utils.safestring import mark_safe
from django.utils.translation import gettext_lazy as _
mark_safe_lazy = lazy(mark_safe, str)
And then later:
lazy_string = mark_safe_lazy(_("<p>My <strong>string!</strong></p>"))
The get_language_info() function provides detailed information about
languages:
>>> from django.utils.translation import activate, get_language_info
>>> activate("fr")
>>> li = get_language_info("de")
>>> print(li["name"], li["name_local"], li["name_translated"], li["bidi"])
German Deutsch Allemand False
The name, name_local, and name_translated attributes of the
dictionary contain the name of the language in English, in the language
itself, and in your current active language respectively. The bidi
attribute is True only for bi-directional languages.
The source of the language information is the django.conf.locale module.
Similar access to this information is available for template code. See below.
Translations in Django 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.
As with all template tags, this tag needs to be loaded in all templates which
use translations, even those templates that extend from other templates which
have already loaded the i18n tag.
Warning
Translated strings will not be escaped when rendered in a template.
This allows you to include HTML in translations, for example for emphasis,
but potentially dangerous characters (e.g. ") will also be rendered
unchanged.
translate template tag¶The {% translate %} template tag translates either a constant string
(enclosed in single or double quotes) or variable content:
<title>{% translate "This is the title." %}</title>
<title>{% translate 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>{% translate "myvar" noop %}</title>
Internally, inline translations use a
gettext() call.
In case a template var (myvar above) is passed to the tag, the tag will
first resolve such variable to a string at run-time and then look up that
string in the message catalogs.
It’s not possible to mix a template variable inside a string within
{% translate %}. If your translations require strings with variables
(placeholders), use {% blocktranslate %} instead.
If you’d like to retrieve a translated string without displaying it, you can use the following syntax:
{% translate "This is the title" as the_title %}
<title>{{ the_title }}</title>
<meta name="description" content="{{ the_title }}">
In practice you’ll use this to get a string you can use in multiple places in a template or so you can use the output as an argument for other template tags or filters:
{% translate "starting point" as start %}
{% translate "end point" as end %}
{% translate "La Grande Boucle" as race %}
<h1>
<a href="/" title="{% blocktranslate %}Back to '{{ race }}' homepage{% endblocktranslate %}">{{ race }}</a>
</h1>
<p>
{% for stage in tour_stages %}
{% cycle start end %}: {{ stage }}{% if forloop.counter|divisibleby:2 %}<br>{% else %}, {% endif %}
{% endfor %}
</p>
{% translate %} also supports contextual markers
using the context keyword:
{% translate "May" context "month name" %}
blocktranslate template tag¶Contrarily to the translate tag, the blocktranslate tag allows you
to mark complex sentences consisting of literals and variable content for
translation by making use of placeholders:
{% blocktranslate %}This string will have {{ value }} inside.{% endblocktranslate %}
To translate a template expression – say, accessing object attributes or using template filters – you need to bind the expression to a local variable for use within the translation block. Examples:
{% blocktranslate with amount=article.price %}
That will cost $ {{ amount }}.
{% endblocktranslate %}
{% blocktranslate with myvar=value|filter %}
This will have {{ myvar }} inside.
{% endblocktranslate %}
You can use multiple expressions inside a single blocktranslate tag:
{% blocktranslate with book_t=book|title author_t=author|title %}
This is {{ book_t }} by {{ author_t }}
{% endblocktranslate %}
Note
The previous more verbose format is still supported:
{% blocktranslate with book|title as book_t and author|title as author_t %}
Other block tags (for example {% for %} or {% if %}) are
not allowed inside a blocktranslate tag.
If resolving one of the block arguments fails, blocktranslate will fall
back to the default language by deactivating the currently active language
temporarily with the deactivate_all()
function.
This tag also provides for pluralization. To use it:
Designate and bind a counter value with the name count. This value will
be the one used to select the right plural form.
Specify both the singular and plural forms separating them with the
{% plural %} tag within the {% blocktranslate %} and
{% endblocktranslate %} tags.
An example:
{% blocktranslate count counter=list|length %}
There is only one {{ name }} object.
{% plural %}
There are {{ counter }} {{ name }} objects.
{% endblocktranslate %}
A more complex example:
{% blocktranslate with amount=article.price count years=i.length %}
That will cost $ {{ amount }} per year.
{% plural %}
That will cost $ {{ amount }} per {{ years }} years.
{% endblocktranslate %}
When you use both the pluralization feature and bind values to local variables
in addition to the counter value, keep in mind that the blocktranslate
construct is internally converted to an ngettext call. This means the
same notes regarding ngettext variables
apply.
Reverse URL lookups cannot be carried out within the blocktranslate and
should be retrieved (and stored) beforehand:
{% url 'path.to.view' arg arg2 as the_url %}
{% blocktranslate %}
This is a URL: {{ the_url }}
{% endblocktranslate %}
If you’d like to retrieve a translated string without displaying it, you can use the following syntax:
{% blocktranslate asvar the_title %}The title is {{ title }}.{% endblocktranslate %}
<title>{{ the_title }}</title>
<meta name="description" content="{{ the_title }}">
In practice you’ll use this to get a string you can use in multiple places in a template or so you can use the output as an argument for other template tags or filters.
In older versions, asvar instances weren’t marked as safe for (HTML)
output purposes.
{% blocktranslate %} also supports contextual
markers using the context keyword:
{% blocktranslate with name=user.username context "greeting" %}Hi {{ name }}{% endblocktranslate %}
Another feature {% blocktranslate %} supports is the trimmed option.
This option will remove newline characters from the beginning and the end of
the content of the {% blocktranslate %} tag, replace any whitespace at the
beginning and end of a line and merge all lines into one using a space
character to separate them. This is quite useful for indenting the content of a
{% blocktranslate %} tag without having the indentation characters end up
in the corresponding entry in the .po file, which makes the translation
process easier.
For instance, the following {% blocktranslate %} tag:
{% blocktranslate trimmed %}
First sentence.
Second paragraph.
{% endblocktranslate %}
will result in the entry "First sentence. Second paragraph." in the .po
file, compared to "\n First sentence.\n Second paragraph.\n", if the
trimmed option had not been specified.
Just like with Python code, these notes for
translators can be specified using comments, either with the comment
tag:
{% comment %}Translators: View verb{% endcomment %}
{% translate "View" %}
{% comment %}Translators: Short intro blurb{% endcomment %}
<p>{% blocktranslate %}A multiline translatable
literal.{% endblocktranslate %}</p>
or with the {# … #} one-line comment constructs:
{# Translators: Label of a button that triggers search #}
<button type="submit">{% translate "Go" %}</button>
{# Translators: This is a text of the base template #}
{% blocktranslate %}Ambiguous translatable block of text{% endblocktranslate %}
Note
Just for completeness, these are the corresponding fragments of the
resulting .po file:
#. Translators: View verb
# path/to/template/file.html:10
msgid "View"
msgstr ""
#. Translators: Short intro blurb
# path/to/template/file.html:13
msgid ""
"A multiline translatable"
"literal."
msgstr ""
# ...
#. Translators: Label of a button that triggers search
# path/to/template/file.html:100
msgid "Go"
msgstr ""
#. Translators: This is a text of the base template
# path/to/template/file.html:103
msgid "Ambiguous translatable block of text"
msgstr ""
If you want to select a language within a template, you can use the
language template tag:
{% load i18n %}
{% get_current_language as LANGUAGE_CODE %}
<!-- Current language: {{ LANGUAGE_CODE }} -->
<p>{% translate "Welcome to our page" %}</p>
{% language 'en' %}
{% get_current_language as LANGUAGE_CODE %}
<!-- Current language: {{ LANGUAGE_CODE }} -->
<p>{% translate "Welcome to our page" %}</p>
{% endlanguage %}
While the first occurrence of “Welcome to our page” uses the current language, the second will always be in English.
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 main solution to these problems is the following JavaScriptCatalog view,
which generates a JavaScript code library with functions that mimic the
gettext interface, plus an array of translation strings.
JavaScriptCatalog view¶A view that produces a JavaScript code library with functions that mimic
the gettext interface, plus an array of translation strings.
Attributes
Translation domain containing strings to add in the view output.
Defaults to 'djangojs'.
A list of application names among
installed applications. Those apps should contain a locale
directory. All those catalogs plus all catalogs found in
LOCALE_PATHS (which are always included) are merged into one
catalog. Defaults to None, which means that all available
translations from all INSTALLED_APPS are provided in the
JavaScript output.
Example with default values:
from django.views.i18n import JavaScriptCatalog
urlpatterns = [
path("jsi18n/", JavaScriptCatalog.as_view(), name="javascript-catalog"),
]
Example with custom packages:
urlpatterns = [
path(
"jsi18n/myapp/",
JavaScriptCatalog.as_view(packages=["your.app.label"]),
name="javascript-catalog",
),
]
If your root URLconf uses i18n_patterns(),
JavaScriptCatalog must also be wrapped by i18n_patterns() for the
catalog to be correctly generated.
Example with i18n_patterns():
from django.conf.urls.i18n import i18n_patterns
urlpatterns = i18n_patterns(
path("jsi18n/", JavaScriptCatalog.as_view(), name="javascript-catalog"),
)
The precedence of translations is such that the packages appearing later in the
packages argument have higher precedence than the ones appearing at the
beginning. This is important in the case of clashing translations for the same
literal.
If you use more than one JavaScriptCatalog view on a site and some of them
define the same strings, the strings in the catalog that was loaded last take
precedence.
To use the catalog, pull in the dynamically generated script like this:
<script src="{% url '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 following methods:
gettext
ngettext
interpolate
get_format
gettext_noop
pgettext
npgettext
pluralidx
gettext¶The gettext function behaves similarly to the standard gettext
interface within your Python code:
document.write(gettext("this is to be translated"))
ngettext¶The ngettext function provides an interface to pluralize words and
phrases:
const objectCount = 1 // or 0, or 2, or 3, ...
const string = ngettext(
'literal for the singular case',
'literal for the plural case',
objectCount
);
interpolate¶The interpolate function supports dynamically populating a format string.
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:
const formats = ngettext(
'There is %s object. Remaining: %s',
'There are %s objects. Remaining: %s',
11
);
const string = interpolate(formats, [11, 20]);
// string 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:
const data = {
count: 10,
total: 50
};
const formats = ngettext(
'Total: %(total)s, there is %(count)s object',
'there are %(count)s of a total of %(total)s objects',
data.count
);
const string = interpolate(formats, data, 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).
get_format¶The get_format function has access to the configured i18n formatting
settings and can retrieve the format string for a given setting name:
document.write(get_format('DATE_FORMAT'));
// 'N j, Y'
It has access to the following settings:
This is useful for maintaining formatting consistency with the Python-rendered values.
gettext_noop¶This emulates the gettext function but does nothing, returning whatever
is passed to it:
document.write(gettext_noop("this will not be translated"))
This is useful for stubbing out portions of the code that will need translation in the future.
pgettext¶The pgettext function behaves like the Python variant
(pgettext()), providing a contextually
translated word:
document.write(pgettext("month name", "May"))
npgettext¶The npgettext function also behaves like the Python variant
(npgettext()), providing a pluralized
contextually translated word:
document.write(npgettext('group', 'party', 1));
// party
document.write(npgettext('group', 'party', 2));
// parties
pluralidx¶The pluralidx function works in a similar way to the pluralize
template filter, determining if a given count should use a plural form of
a word or not:
document.write(pluralidx(0));
// true
document.write(pluralidx(1));
// false
document.write(pluralidx(2));
// true
In the simplest case, if no custom pluralization is needed, this returns
false for the integer 1 and true for all other numbers.
However, pluralization is not this simple in all languages. If the language does not support pluralization, an empty value is provided.
Additionally, if there are complex rules around pluralization, the catalog view
will render a conditional expression. This will evaluate to either a true
(should pluralize) or false (should not pluralize) value.
JSONCatalog view¶In order to use another client-side library to handle translations, you may
want to take advantage of the JSONCatalog view. It’s similar to
JavaScriptCatalog but returns a JSON response.
See the documentation for JavaScriptCatalog
to learn about possible values and use of the domain and packages
attributes.
The response format is as follows:
{
"catalog": {
# Translations catalog
},
"formats": {
# Language formats for date, time, etc.
},
"plural": "..." # Expression for plural forms, or null.
}
The various JavaScript/JSON i18n views generate the catalog from .mo files
on every request. Since its output is constant, at least for a given version
of a site, it’s a good candidate for caching.
Server-side caching will reduce CPU load. It’s easily implemented with the
cache_page() decorator. To trigger cache
invalidation when your translations change, provide a version-dependent key
prefix, as shown in the example below, or map the view at a version-dependent
URL:
from django.views.decorators.cache import cache_page
from django.views.i18n import JavaScriptCatalog
# The value returned by get_version() must change when translations change.
urlpatterns = [
path(
"jsi18n/",
cache_page(86400, key_prefix="jsi18n-%s" % get_version())(
JavaScriptCatalog.as_view()
),
name="javascript-catalog",
),
]
Client-side caching will save bandwidth and make your site load faster. If
you’re using ETags (ConditionalGetMiddleware),
you’re already covered. Otherwise, you can apply conditional decorators. In the following example, the cache is invalidated
whenever you restart your application server:
from django.utils import timezone
from django.views.decorators.http import last_modified
from django.views.i18n import JavaScriptCatalog
last_modified_date = timezone.now()
urlpatterns = [
path(
"jsi18n/",
last_modified(lambda req, **kw: last_modified_date)(
JavaScriptCatalog.as_view()
),
name="javascript-catalog",
),
]
You can even pre-generate the JavaScript catalog as part of your deployment procedure and serve it as a static file. This radical technique is implemented in django-statici18n.
Django provides two mechanisms to internationalize URL patterns:
Adding the language prefix to the root of the URL patterns to make it
possible for LocaleMiddleware to detect
the language to activate from the requested URL.
Making URL patterns themselves translatable via the
django.utils.translation.gettext_lazy() function.
Warning
Using either one of these features requires that an active language be set
for each request; in other words, you need to have
django.middleware.locale.LocaleMiddleware in your
MIDDLEWARE setting.
This function can be used in a root URLconf and Django will automatically
prepend the current active language code to all URL patterns defined within
i18n_patterns().
Setting prefix_default_language to False removes the prefix from the
default language (LANGUAGE_CODE). This can be useful when adding
translations to existing site so that the current URLs won’t change.
Example URL patterns:
from django.conf.urls.i18n import i18n_patterns
from django.urls import include, path
from about import views as about_views
from news import views as news_views
from sitemap.views import sitemap
urlpatterns = [
path("sitemap.xml", sitemap, name="sitemap-xml"),
]
news_patterns = (
[
path("", news_views.index, name="index"),
path("category/<slug:slug>/", news_views.category, name="category"),
path("<slug:slug>/", news_views.details, name="detail"),
],
"news",
)
urlpatterns += i18n_patterns(
path("about/", about_views.main, name="about"),
path("news/", include(news_patterns, namespace="news")),
)
After defining these URL patterns, Django will automatically add the
language prefix to the URL patterns that were added by the i18n_patterns
function. Example:
>>> from django.urls import reverse
>>> from django.utils.translation import activate
>>> activate("en")
>>> reverse("sitemap-xml")
'/sitemap.xml'
>>> reverse("news:index")
'/en/news/'
>>> activate("nl")
>>> reverse("news:detail", kwargs={"slug": "news-slug"})
'/nl/news/news-slug/'
With prefix_default_language=False and LANGUAGE_CODE='en', the URLs
will be:
>>> activate("en")
>>> reverse("news:index")
'/news/'
>>> activate("nl")
>>> reverse("news:index")
'/nl/news/'
Warning
i18n_patterns() is only allowed in a root
URLconf. Using it within an included URLconf will throw an
ImproperlyConfigured exception.
Warning
Ensure that you don’t have non-prefixed URL patterns that might collide with an automatically-added language prefix.
URL patterns can also be marked translatable using the
gettext_lazy() function. Example:
from django.conf.urls.i18n import i18n_patterns
from django.urls import include, path
from django.utils.translation import gettext_lazy as _
from about import views as about_views
from news import views as news_views
from sitemaps.views import sitemap
urlpatterns = [
path("sitemap.xml", sitemap, name="sitemap-xml"),
]
news_patterns = (
[
path("", news_views.index, name="index"),
path(_("category/<slug:slug>/"), news_views.category, name="category"),
path("<slug:slug>/", news_views.details, name="detail"),
],
"news",
)
urlpatterns += i18n_patterns(
path(_("about/"), about_views.main, name="about"),
path(_("news/"), include(news_patterns, namespace="news")),
)
After you’ve created the translations, the reverse()
function will return the URL in the active language. Example:
>>> from django.urls import reverse
>>> from django.utils.translation import activate
>>> activate("en")
>>> reverse("news:category", kwargs={"slug": "recent"})
'/en/news/category/recent/'
>>> activate("nl")
>>> reverse("news:category", kwargs={"slug": "recent"})
'/nl/nieuws/categorie/recent/'
Warning
In most cases, it’s best to use translated URLs only within a language code
prefixed block of patterns (using
i18n_patterns()), to avoid the possibility
that a carelessly translated URL causes a collision with a non-translated
URL pattern.
If localized URLs get reversed in templates they always use the current
language. To link to a URL in another language use the language
template tag. It enables the given language in the enclosed template section:
{% load i18n %}
{% get_available_languages as languages %}
{% translate "View this category in:" %}
{% for lang_code, lang_name in languages %}
{% language lang_code %}
<a href="{% url 'category' slug=category.slug %}">{{ lang_name }}</a>
{% endlanguage %}
{% endfor %}
The language tag expects the language code as the only argument.
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.
The first step is to create a 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 makemessages, that automates the creation and upkeep of these files.
Gettext utilities
The makemessages command (and compilemessages discussed later) use
commands from the GNU gettext toolset: xgettext, msgfmt,
msgmerge and msguniq.
The minimum version of the gettext utilities supported is 0.15.
To create or update a message file, run this command:
django-admin makemessages -l de
…where de is the locale name for the message file you want to
create. For example, pt_BR for Brazilian Portuguese, de_AT for Austrian
German or id for Indonesian.
The script should be run from one of two places:
The root directory of your Django project (the one that contains
manage.py).
The root directory of one of your Django apps.
The script runs over your project source tree or your application source tree
and pulls out all strings marked for translation (see
How Django discovers translations and be sure LOCALE_PATHS
is configured correctly). 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.
When you run makemessages from the root directory of your project, the
extracted strings will be automatically distributed to the proper message files.
That is, a string extracted from a file of an app containing a locale
directory will go in a message file under that directory. A string extracted
from a file of an app without any locale directory will either go in a
message file under the directory listed first in LOCALE_PATHS or
will generate an error if LOCALE_PATHS is empty.
By default django-admin makemessages examines every
file that has the .html, .txt or .py file extension. If you want to
override that default, use the --extension
or -e option to specify the file extensions to examine:
django-admin makemessages -l de -e txt
Separate multiple extensions with commas and/or use -e or --extension
multiple times:
django-admin makemessages -l de -e html,txt -e xml
Warning
When creating message files from JavaScript source code you need to use the special
djangojs domain, not -e js.
Using Jinja2 templates?
makemessages doesn’t understand the syntax of Jinja2 templates.
To extract strings from a project containing Jinja2 templates, use Message
Extracting from Babel instead.
Here’s an example babel.cfg configuration file:
# Extraction from Python source files
[python: **.py]
# Extraction from Jinja2 templates
[jinja2: **.jinja]
extensions = jinja2.ext.with_
Make sure you list all extensions you’re using! Otherwise Babel won’t recognize the tags defined by these extensions and will ignore Jinja2 templates containing them entirely.
Babel provides similar features to makemessages, can replace it
in general, and doesn’t depend on gettext. For more information, read
its documentation about working with message catalogs.
No gettext?
If you don’t have the gettext utilities installed,
makemessages will create empty files. If that’s the case, either
install the gettext utilities or copy the English message file
(locale/en/LC_MESSAGES/django.po) if available and use it as a starting
point, which is an empty translation file.
Working on Windows?
If you’re using Windows and need to install the GNU gettext utilities so
makemessages works, see gettext on Windows for more
information.
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 – 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 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!
Mind your charset
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 files (the default when
.po files are created). This means that everybody will be using the
same encoding, which is important when Django processes the .po files.
Fuzzy entries
makemessages sometimes generates translation entries marked as
fuzzy, e.g. when translations are inferred from previously translated
strings. By default, fuzzy entries are not processed by
compilemessages.
To reexamine all source code and templates for new translation strings and update all message files for all languages, run this:
django-admin makemessages -a
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 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 makemessages, run
django-admin compilemessages like this:
django-admin compilemessages
That’s it. Your translations are ready for use.
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.
.po files: Encoding and BOM usage.
Django only supports .po files encoded in UTF-8 and without any BOM
(Byte Order Mark) so if your text editor adds such marks to the beginning of
files by default then you will need to reconfigure it.
gettext() incorrectly detects python-format in strings with percent signs¶In some cases, such as strings with a percent sign followed by a space and a
string conversion type (e.g.
_("10% interest")), gettext() incorrectly
flags strings with python-format.
If you try to compile message files with incorrectly flagged strings, you’ll
get an error message like number of format specifications in 'msgid' and
'msgstr' does not match or 'msgstr' is not a valid Python format string,
unlike 'msgid'.
To workaround this, you can escape percent signs by adding a second percent sign:
from django.utils.translation import gettext as _
output = _("10%% interest")
Or you can use no-python-format so that all percent signs are treated as
literals:
# xgettext:no-python-format
output = _("10% interest")
You create and update the message files the same way as the other Django message
files – with the django-admin makemessages tool.
The only difference is you need to explicitly specify what in gettext parlance
is known as a domain in this case the djangojs domain, by providing a -d
djangojs parameter, like this:
django-admin makemessages -d djangojs -l de
This would create or update the message file for JavaScript for German. After
updating message files, run django-admin compilemessages the same way as you do with normal Django message files.
gettext on Windows¶This is only needed for people who either want to extract message IDs or compile
message files (.po). Translation work itself 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, download a precompiled binary
installer.
You may also use gettext binaries you have obtained elsewhere, so long as
the xgettext --version command works properly. 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”.
makemessages command¶If you want to pass additional parameters to xgettext, you need to create a
custom makemessages command and override its xgettext_options
attribute:
from django.core.management.commands import makemessages
class Command(makemessages.Command):
xgettext_options = makemessages.Command.xgettext_options + ["--keyword=mytrans"]
If you need more flexibility, you could also add a new argument to your custom
makemessages command:
from django.core.management.commands import makemessages
class Command(makemessages.Command):
def add_arguments(self, parser):
super().add_arguments(parser)
parser.add_argument(
"--extra-keyword",
dest="xgettext_keywords",
action="append",
)
def handle(self, *args, **options):
xgettext_keywords = options.pop("xgettext_keywords")
if xgettext_keywords:
self.xgettext_options = makemessages.Command.xgettext_options[:] + [
"--keyword=%s" % kwd for kwd in xgettext_keywords
]
super().handle(*args, **options)
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 to a given URL or, by default,
back to the previous page.
Activate this view by adding the following line to your URLconf:
path("i18n/", include("django.conf.urls.i18n")),
(Note that this example makes the view available at /i18n/setlang/.)
Warning
Make sure that you don’t include the above URL within
i18n_patterns() - it needs to be
language-independent itself to work correctly.
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. It also saves the language choice in a
cookie that is named django_language by default. (The name can be changed
through the LANGUAGE_COOKIE_NAME setting.)
After setting the language choice, Django looks for a next parameter in the
POST or GET data. If that is found and Django considers it to be a safe
URL (i.e. it doesn’t point to a different host and uses a safe scheme), a
redirect to that URL will be performed. Otherwise, Django may fall back to
redirecting the user to the URL from the Referer header or, if it is not
set, to /, depending on the nature of the request:
If the request accepts HTML content (based on its Accept HTTP header),
the fallback will always be performed.
If the request doesn’t accept HTML, the fallback will be performed only if
the next parameter was set. Otherwise a 204 status code (No Content) will
be returned.
Here’s example HTML template code:
{% load i18n %}
<form action="{% url 'set_language' %}" method="post">{% csrf_token %}
<input name="next" type="hidden" value="{{ redirect_to }}">
<select name="language">
{% get_current_language as LANGUAGE_CODE %}
{% get_available_languages as LANGUAGES %}
{% get_language_info_list for LANGUAGES as languages %}
{% for language in languages %}
<option value="{{ language.code }}"{% if language.code == LANGUAGE_CODE %} selected{% endif %}>
{{ language.name_local }} ({{ language.code }})
</option>
{% endfor %}
</select>
<input type="submit" value="Go">
</form>
In this example, Django looks up the URL of the page to which the user will be
redirected in the redirect_to context variable.
You may want to set the active language for the current session explicitly. Perhaps
a user’s language preference is retrieved from another system, for example.
You’ve already been introduced to django.utils.translation.activate(). That
applies to the current thread only. To persist the language for the entire
session in a cookie, set the LANGUAGE_COOKIE_NAME cookie on the
response:
from django.conf import settings
from django.http import HttpResponse
from django.utils import translation
user_language = "fr"
translation.activate(user_language)
response = HttpResponse(...)
response.set_cookie(settings.LANGUAGE_COOKIE_NAME, user_language)
You would typically want to use both: django.utils.translation.activate()
changes the language for this thread, and setting the cookie makes this
preference persist in future requests.
While Django provides a rich set of i18n tools for use in views and templates, it does not restrict the usage to Django-specific code. The Django translation mechanisms can be used to translate arbitrary texts to any language that is supported by Django (as long as an appropriate translation catalog exists, of course). You can load a translation catalog, activate it and translate text to language of your choice, but remember to switch back to original language, as activating a translation catalog is done on per-thread basis and such change will affect code running in the same thread.
For example:
from django.utils import translation
def welcome_translated(language):
cur_language = translation.get_language()
try:
translation.activate(language)
text = translation.gettext("welcome")
finally:
translation.activate(cur_language)
return text
Calling this function with the value 'de' will give you "Willkommen",
regardless of LANGUAGE_CODE and language set by middleware.
Functions of particular interest are
django.utils.translation.get_language() which returns the language used
in the current thread, django.utils.translation.activate() which
activates a translation catalog for the current thread, and
django.utils.translation.check_for_language()
which checks if the given language is supported by Django.
To help write more concise code, there is also a context manager
django.utils.translation.override() that stores the current language on
enter and restores it on exit. With it, the above example becomes:
from django.utils import translation
def welcome_translated(language):
with translation.override(language):
return translation.gettext("welcome")
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.
Once you’ve prepared your translations – or, if you want to use the translations that come with Django – you’ll 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 LANGUAGE_CODE.
Django uses this language as the default translation – the final attempt if no
better matching translation is found through one of the methods employed by the
locale middleware (see below).
If all you want is to run Django with your native language all you need to do
is set LANGUAGE_CODE and make sure the corresponding message
files and their compiled versions (.mo) exist.
If you want to let each individual user specify which language they
prefer, then you also need to use the 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 setting. Because middleware order matters, follow
these guidelines:
Make sure it’s one of the first middleware installed.
It should come after SessionMiddleware, because LocaleMiddleware
makes use of session data. And it should come before CommonMiddleware
because CommonMiddleware needs an activated language in order
to resolve the requested URL.
If you use CacheMiddleware, put LocaleMiddleware after it.
For example, your MIDDLEWARE might look like this:
MIDDLEWARE = [
"django.contrib.sessions.middleware.SessionMiddleware",
"django.middleware.locale.LocaleMiddleware",
"django.middleware.common.CommonMiddleware",
]
(For more on middleware, see the middleware documentation.)
LocaleMiddleware tries to determine the user’s language preference by
following this algorithm:
First, it looks for the language prefix in the requested URL. This is
only performed when you are using the i18n_patterns function in your
root URLconf. See Internationalization: in URL patterns for more information
about the language prefix and how to internationalize URL patterns.
Failing that, it looks for a cookie.
The name of the cookie used 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.
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 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).
If you define a custom LANGUAGES setting, as explained in the
previous bullet, you can mark the language names as translation strings
– but use gettext_lazy() instead of
gettext() to avoid a circular import.
Here’s a sample settings file:
from django.utils.translation import gettext_lazy as _
LANGUAGES = [
("de", _("German")),
("en", _("English")),
]
Once LocaleMiddleware determines the user’s preference, it makes this
preference available as request.LANGUAGE_CODE for each
HttpRequest. Feel free to read this value in your view
code. Here’s an example:
from django.http import HttpResponse
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.
At runtime, Django builds an in-memory unified catalog of literals-translations.
To achieve this it looks for translations by following this algorithm regarding
the order in which it examines the different file paths to load the compiled
message files (.mo) and the precedence of multiple
translations for the same literal:
The directories listed in LOCALE_PATHS have the highest
precedence, with the ones appearing first having higher precedence than
the ones appearing later.
Then, it looks for and uses if it exists a locale directory in each
of the installed apps listed in INSTALLED_APPS. The ones
appearing first have higher precedence than the ones appearing later.
Finally, the Django-provided base translation in django/conf/locale is used as a fallback.
See also
The translations for literals included in JavaScript assets are looked up
following a similar but not identical algorithm. See
JavaScriptCatalog for more details.
You can also put custom format files in the
LOCALE_PATHS directories if you also set
FORMAT_MODULE_PATH.
In all cases the name of the directory containing the translation is expected to
be named using locale name notation. E.g. de, pt_BR, es_AR,
etc. Untranslated strings for territorial language variants use the translations
of the generic language. For example, untranslated pt_BR strings use pt
translations.
This way, you can write applications that include their own translations, and you can override base translations in your project. Or, you can build a big project out of several apps and put all translations into one big common message file specific to the project you are composing. The choice is yours.
All message file repositories are structured the same way. They are:
All paths listed in LOCALE_PATHS in your settings file are
searched for <language>/LC_MESSAGES/django.(po|mo)
$APPPATH/locale/<language>/LC_MESSAGES/django.(po|mo)
$PYTHONPATH/django/conf/locale/<language>/LC_MESSAGES/django.(po|mo)
To create message files, you use the django-admin makemessages
tool. And you use django-admin compilemessages
to produce the binary .mo files that are used by gettext.
You can also run django-admin compilemessages
--settings=path.to.settings to make the compiler process all
the directories in your LOCALE_PATHS setting.
Django makes the general assumption that the original strings in a translatable project are written in English. You can choose another language, but you must be aware of certain limitations:
gettext only provides two plural forms for the original messages, so you
will also need to provide a translation for the base language to include all
plural forms if the plural rules for the base language are different from
English.
When an English variant is activated and English strings are missing, the
fallback language will not be the LANGUAGE_CODE of the project,
but the original strings. For example, an English user visiting a site with
LANGUAGE_CODE set to Spanish and original strings written in
Russian will see Russian text rather than Spanish.
Dec 25, 2023
Comments for translators¶
If you would like to give translators hints about a translatable string, you can add a comment prefixed with the
Translatorskeyword on the line preceding the string, e.g.:The comment will then appear in the resulting
.pofile associated with the translatable construct located below it and should also be displayed by most translation tools.Note
Just for completeness, this is the corresponding fragment of the resulting
.pofile:This also works in templates. See Comments for translators in templates for more details.