Django: Use of DATE_FORMAT, DATETIME_FORMAT, TIME_FORMAT in settings.py? - django

Question

I would like to globally (through my entire site, admin and front-end) adjust the way dates and time are displayed to my likings, but I cannot figure out what is going on with the DATE_FORMAT, DATETIME_FORMAT and TIME_FORMAT variables in settings.py.
In this question it says that the settings are ignored. The question is over a year old though. In the Django documentation it says they can be used when you have USE_L10N = True and apparently something changed in Django 1.2. According to this however there might be a bug.
I am currently using Django 1.2 and when I have USE_L10N = True it just ignores the date(time) format in settings.py. When I have USE_L10N = False it also seems to ignore them.
Is there a way to globally customize the date and time display? Or should I create my own custom formats file as Karen suggests in the Django Users Google Group post?

Answer 1

Had same problem, solution is simple and documented. Whenever you render a date, you need to specify you want the template to render it as a date/time/short_date/datetime (e.g., {{ some_date_var | date }} and then it will render it as specified with DATE_FORMAT in your settings.py
Example:
>>> from django.conf import settings # imported to show my variables in settings.py
>>> settings.DATE_FORMAT # - showing my values; I modified this value
'm/d/Y'
>>> settings.TIME_FORMAT
'P'
>>> settings.DATETIME_FORMAT
'N j, Y, P'
>>> from django.template import Template, Context
>>> from datetime import datetime
>>> c = Context(dict(moon = datetime(1969, 7, 20, 20, 17, 39))) # Create context with datetime to render in a template
>>> print c['moon'] # This is the default format of a printing datetime object
1969-07-20 20:17:39
>>> print Template("default formatting : {{ moon }}\n"
"use DATE_FORMAT : {{ moon|date }}\n"
"use TIME_FORMAT : {{ moon|time }}\n"
"use DATETIME_FORMAT: {{ moon|date:'DATETIME_FORMAT' }}\n"
"use SHORT_DATETIME_FORMAT: {{ moon|date:'SHORT_DATETIME_FORMAT' }}"
).render(c)
default formatting : 1969-07-20 20:17:39
use DATE_FORMAT : 07/20/1969
use TIME_FORMAT : 8:17 p.m.
use DATETIME_FORMAT: July 20, 1969, 8:17 p.m.
use SHORT_DATETIME_FORMAT: 07/20/1969 8:17 p.m.
This makes sense; e.g., the template needs to know whether it should use the DATE_FORMAT or the SHORT_DATE_FORMAT or whatever.

Answer 2

Searching through the source shows that DATETIME_FORMAT, etc., are only used when django.utils.formats.localize() is called, and that only seems to be called when django.template.VariableNodes are rendered.
I'm not sure when exactly VariableNodes are used in template rendering, but I would guess that if you have settings.USE_L10N turned on and you have a VariableNode, it will be localized.
localize looks like this:
def localize(value):
"""
Checks if value is a localizable type (date, number...) and returns it
formatted as a string using current locale format
"""
if settings.USE_L10N:
if isinstance(value, (decimal.Decimal, float, int)):
return number_format(value)
elif isinstance(value, datetime.datetime):
return date_format(value, 'DATETIME_FORMAT')
elif isinstance(value, datetime.date):
return date_format(value)
elif isinstance(value, datetime.time):
return time_format(value, 'TIME_FORMAT')
return value
To answer your question, I'd probably write a quick context processor that called localize() on everything in the context.

Answer 3

You can override DATE_FORMAT, DATETIME_FORMAT, TIME_FORMAT and other date/time formats when USE_L10N = True by creating custom format files as described in Django documentation.
In summary:
Set FORMAT_MODULE_PATH = 'yourproject.formats' in settings.py
Create directory structure yourproject/formats/en (replacing en with the corresponding ISO 639-1 locale code if you are using other locale than English) and add __init__.py files to all directories to make it a valid Python module
Add formats.py to the leaf directory, containing the format definitions you want to override, e.g. DATE_FORMAT = 'j. F Y'.
Example from an actual project here.

Answer 4

A late response, but hopefully this will help anyone else searching for this.
By setting USE_L10N = True in your settings, Django looks for locale specific formats, giving them precedence over non-locale related settings.
The solution: (to display 30/12/2017 on a DateField)
from django.conf.locale.en import formats as en_formats
en_formats.DATE_FORMAT = "%d/%m/%Y"
and for inputs (to accept 30/12/2017 or 30-12-2017)
en_formats.DATE_INPUT_FORMATS = ['%d/%m/%Y', '%d-%m-%Y']
Reference: https://mounirmesselmeni.github.io/2014/11/06/date-format-in-django-admin/
*tested on Django==1.10.7