newforms: DateField doesn't handle date output formats

[orestis@…]

As it stands, the when using a newforms.DateField with specified input
formats, it gets parsed alright, but when rendering the form there is
no way to specify the output format, it gets printed as YYYY-MM-DD.

By looking in the source code, I haven't been able to find anything related to this, so I think DateField needs some tweaking.

This not only is a bad localization practice, it makes _using_ the
input formats impossible, since when re-submitting a populated form
without changes, you get validation errors.

Since we can define multiple input formats, but there is only one output format (obviously), I suggest:

a) Defining a new parameter, output_format
b) Make it optional, and set it to the first input format defined in the form field.

[scott@…]

I ran in to the same problem today. Seems like maybe this is a job for the widget, rather than the field? My interim solution was to write widgets that derive from TextInput, override render and format the value before it is written out. Code for the widgets is attached.

Usage:

class MyForm(forms.Form):
    date = forms.DateField(widget=DateFormattedTextInput())
    time = forms.TimeField(widget=TimeFormattedTextInput())
    # or pass output format to widget:
    date = forms.DateField(widget=DateFormattedTextInput(format='j M Y'))

[scott@…]

Widgets that format date or time before rendering

[Ville Säävuori <Ville@…>]

I ran into this today.

For me it would be enough to make the field render its content according to input_formats parameter.

But as said, this bug indeed leaves the DateField unusable for now :(

[Ville Säävuori <Ville@…>]

Whipped up a quick workaround:

First, make timeformat variable

from datetime import date
TIME_FORMAT = '%d.%m.%Y'

then use it in input_formats

date_of_birth = forms.DateField(input_formats=[TIME_FORMAT], label="Date of Birth", required=False, help_text="Format like 17.12.1979")

and when initializing the form, use strftime

date_of_birth = user.get_profile().date_of_birth
form = MyForm(initial={'date_of_birth': date_of_birth.strftime(TIME_FORMAT)})

Not very DRY or pretty, but it seems to work.

[scott@…]

Bug fix: If an invalid date or time is entered the widgets don't try to format it

[James Bennett]

See also #3533.

[Gary Wilson]

I'm leaning towards the patch attached to this ticket rather than the one on #3533 since the one here splits the Date and Time widgets and makes use of formats in settings.py.

How about some tests and a patch in diff format.

[scott@…]

Widgets (slightly remodeled) and tests as a diff

[scott@…]

Note that these widgets take a Django style format string like 'N j, Y' versus Python strftime() style like '%b %d, %Y'.

It means you could have a field definition with two different styles of date format strings like:

class MyForm(forms.Form):
    start_date  = forms.DateField(widget=DateTextInput(format='d/m/y'), input_formats=('%d/%m/%y',))

However, I think it makes sense to use Django format strings for output since it is used elsewhere in the UI and is perhaps more powerful. DateField uses strftime() patterns for input, but it is parsing using strptime() so that's the natural format.

[David Jones <davesgonebananas@…>]

Found this incredibly useful. Have implemented a modified version that uses datetime.strftime and it is working perfectly for me. However, I'm surprised this has been open for 1 year and has not made yet it into trunk.

[Adi J. Sieker]

updated to work with trunk and use translated DATE_FORMAT and TIME_FORMAT as well

[Adi J. Sieker]

new patch now works with trunk.

I also changed how the date and time formats are determined.

1. user supplied
2. format from translation using ugettext
3. format from settings.

I also tried to add the new text inputs as default widgets to the DateField and TimeField model fields.
This breaks forms tests and modelforms tests, since the tests supply unicode strings instead of datetime.date or datetime objects to the date and time widgets. The new widgets return None if they are not supplied with a datetime.date or datetime.datetime instances.

Now my question is: Does a widgets have to handle unicode strings (thinking about POST or GET values) or do the widgets always get value from to_python?
Actually thinking about it some more having to handle unicode is probably a must since I can use a Form without a Model.

So I'd leave unicode strings as they are and only format date and datetime instance. Is that OK?

[Adi J. Sieker]

update the patch again, removed the usage for DATE_FORMAT from the translation.

[Adi J. Sieker]

the usage of DATE_FORMAT from the translation or utils.translation.get_date_format doesn't actually make much sense for input control. The german DATE_FORMAT is 12. Apr 2008 which, when displayed in an input control doesn't feel correct.

[Dinoboff]

Thanks for the patches. I am new to Python and Django can't really understand how all that works.

Here the solution for DateField that I am using; it doesn't rely on settings.DATE_FORMAT but on the field input_formats property:

from django import newforms as forms
from django.newforms.fields import DEFAULT_DATE_INPUT_FORMATS
import datetime

DEFAULT_DATE_OUTPUT_FORMATS = DEFAULT_DATE_INPUT_FORMATS[0]

class FormattedTextInput(forms.widgets.TextInput):
    "Overrides TextInput to render formatted value."
    def render(self, name, value, attrs=None):
        formatted_value = None
        if value:
            formatted_value = self.format_value(value)
        return super(FormattedTextInput, self).render(name, formatted_value, attrs)

class DateFormattedTextInput(FormattedTextInput):
    "Renders formatted date."
    def __init__(self, format=None, attrs=None):
        super(DateFormattedTextInput, self).__init__(attrs)
        self.format = format or DEFAULT_DATE_OUTPUT_FORMATS

    def format_value(self, value):
        if isinstance(value, datetime.date) or isinstance(value, datetime.datetime):
            return value.strftime(self.format)
        else:
            return value

class DateField(forms.DateField):
    widget = DateFormattedTextInput

    def __init__(self, *args, **kwargs):
        super(DateField, self).__init__(*args, **kwargs)
        self.widget.format = self.input_formats[0]

Hope it helps.

[Dinoboff]

Patch and test

[anonymous]

DateTimeField's widget (DateTimeInput) already allows to format date and datetime object.

[marxis.rene@…]

Hello

i think

def format_value(self, value):

if isinstance(value, datetime.date) or isinstance(value, datetime.datetime):

return value.strftime(self.format)

else:

return value

needs to be changed to:

def format_value(self, value):

if isinstance(value, datetime.date) or isinstance(value, datetime.datetime):

try:

return value.strftime(self.format)

except:

return value

else:

return value

Otherwise the value.strftime(self.format) would crash the form (form render returns "") if the field-value does not validate on calling form.is_valid()

If my approach is wrong please let me know. I'm very new to django/python :)

[(none)]

Milestone post-1.0 deleted

[Adam Nelson]

No response to marxis.rene@googlemail.com yet so marking as patch needs improvement until somebody responds to that issue. Comment 15 marks this as not even relevant anymore - not sure either way.

[Ramiro Morales]

I think these needs were fulfilled with the changes introduced in r11964 (GSoC 2010 project) and further refinements committed later since then.