How to format a number in django and respect localization

Question

I wrote a custom filter like this which calls this method in a util file:

def util_format_number(value):
    return "{:,.1f}".format(value)

The idea is to only show one decimal place...but when used inside a template it won't give me a localized number like I have configured in settings:

LANGUAGE_CODE = 'es-es'
USE_I18N = True
USE_L10N = True
USE_THOUSAND_SEPARATOR = True
DECIMAL_SEPARATOR = ','
THOUSAND_SEPARATOR = '.'
NUMBER_GROUPING = 3

The desired result would be 23.444.523,3

My actual filter looks like this:

@register.filter
def format_number(value):
    return util_format_number(value)

I want to be able to use the formatter not only in templates, but inside view code where I create custom graphs (that I later print in the templates).

Any hints?

Best regards and thanks in advance.

Answer 1

If this number format is your localized format, there's a builtin filter that does what I believe your filter is trying to accomplish: https://docs.djangoproject.com/en/2.0/topics/i18n/formatting/#template-filters

If that's not your speed, and you want something a bit more customized, you can take the localization call from the source code of that filter and customize it for your needs:

from django.utils import formats
@register.filter
def format_number(value):
    l10n_num = formats.localize(value, use_l10n=True)
    # Do something else here
    return l10n_num

Hope this can help you out!