Django: How to force translation into a given language inside a template ?

Question

In a Django template, I need to transanlate some strings to a specific language (different from current one).

I would need something like this:

{% tans_to "de" "my string to translate" %}
or
{% blocktrans_to "de" %}my bloc to translate {% endblocktrans_to %}

to force translation to German.

I know I can call the following code in a view:

gettext.translation('django', 'locale', ['de'], fallback=True).ugettext("my string to translate")

Do I need to create a specific template tag ? Or does it already exist a dedicated tag in Django ?

Answer 1

You could use the trans template tag inside your templates to translate strings to the desired language:

{% load i18n %}
{% trans "Hello" %}

You have to have USE_I18N set to True inside the settings.py file.

Then you define LANGUAGE_CODE to control the default language for the whole site and add the LocaleMiddleware class to your MIDDLEWARE_CLASSES. Check out the How Django Discovers Language Preference section from the documentation.

Answer 2

templatetags/trans_to.py:

from django.utils import translation
from django.utils.translation import ugettext
from django.template import Library, Node,  Variable, TemplateSyntaxError
register = Library()

class TransNode(Node):
    def __init__(self, value, lc):
        self.value = Variable(value)
        self.lc = lc

    def render(self, context):        
        translation.activate(self.lc)
        val = ugettext(self.value.resolve(context))        
        translation.deactivate()        
        return val

def trans_to(parser, token):
    try:
        tag_name, value, lc = token.split_contents()
    except ValueError:
        raise TemplateSyntaxError, "%r tag requires arguments" % token.contents.split()[0]
    if not (lc[0] == lc[-1] and lc[0] in ('"', "'")):
        raise TemplateSyntaxError, "%r locale should be in quotes" % tag_name 
    return TransNode(value, lc[1:-1])

register.tag('trans_to', trans_to)

html:

{% load trans_to %}
{# pass string #}   
<p>{% trans_to "test" "de" %}</p>
<p>{% trans "test" %}</p>
{# pass variable #}
{% with "test" as a_variable %}
<p>{% trans_to a_variable "de" %}</p>
<p>{% trans a_variable %}</p>       
{% endwith %}

result:

<p>test in deutsch</p>
<p>test</p>
<p>test in deutsch</p>
<p>test</p>

Answer 3

This a modified version of Zalew's code which allows template's variable for the locale parameter:

from django.utils import translation
from django.template import Library, Node,  Variable, TemplateSyntaxError
register = Library()

class TransNode(Node):
    def __init__(self, value, lc):
        self.value = Variable(value)
        self.lc =  Variable(lc)

    def render(self, context):
        translation.activate(self.lc.resolve(context))
        val = translation.ugettext(self.value.resolve(context))        
        translation.deactivate()
        return val

def trans_to(parser, token):
    """ 
    force translation into a given language
      usage : {% trans_to "string to translate" locale %}
    """
    try:
        tag_name, value, lc = token.split_contents()
    except ValueError:
            raise TemplateSyntaxError, '%r tag usage: {%% trans_to "string to translate" locale %%}' % token.contents.split()[0]
    return TransNode(value, lc)

register.tag('trans_to', trans_to)