forms.DateTimeField() rendered with HiddenInput looses microseconds

if you just want this to work and you don't want to patch django you can use this:

http://www.djangosnippets.org/snippets/1342/

On a related note:

Rendering the DateTimeField? as a hidden field, {{ field.as_hidden }}, will make the form invalid when submitting because the HiddenInput? keeps the microseconds and the field validation does not.

The proposed patch is extremely brittle - it only works providing you don't use a '.' in the your custom rendering of datetime. If you allow an input format of '%Y.%m.%d %H:%M:%S", the code will break hard.

If you dig into the code, it isn't just HiddenField? that is affected by this - the default DateTimeField? also loses milliseconds. Essentially, what is required is a way to parse milliseconds from a string. Python 2.6 adds %f to strftime/strptime, which will solve this problem - you can then allow "%Y-%m-%d %H:%M:%S.%f" as an input format. We may need to port strftime and strptime back from Python 2.6. Other options also welcome.

This problem:

1. Is Annoying
2. Has always existed in newforms, and probably in oldforms before that
3. Only affects a subset of the user community

Since the required fix will be quite big, and we're already overdue for v1.1, I'm going to drop this from the v1.1 roadmap. If someone wants to tackle porting strptime and strftime (and this includes resolving any licensing issues) and they can get a patch ready quickly, feel free to put this back on the v1.1 path.

Slightly more acceptable approach, with a couple bug fixes:

class DateTimeWithUsecsField(forms.DateTimeField):
    def clean(self, value):
        if value and '.' in value: 
            value, usecs = value.rsplit('.', 1)
            usecs += '0'*(6-len(usecs)) # right pad with zeros if necessary
            try:
                usecs = int(usecs) 
            except ValueError: 
                raise ValidationError('Microseconds must be an integer') 
        else: 
            usecs = 0 
        cleaned_value = super(DateTimeWithUsecsField, self).clean(value)
        if cleaned_value:
            cleaned_value = cleaned_value.replace(microsecond=usecs)
        return cleaned_value

Also updated at http://www.djangosnippets.org/snippets/1342/

The version of this ticket is 1.0. I guess this bug also affects trunk. Can someone confirm this and change the Version to SVN?

Replying to bjunix:

The version of this ticket is 1.0. I guess this bug also affects trunk. Can someone confirm this and change the Version to SVN?

If the version when reported was 1.0, and the ticket is still open, then likely the behavior is still present in trunk. (There's some chance an unrelated or unrealized-duplicate ticket changed the behavior, so it's only likely and not certain, but it seems unlikely that has happened in this particular case.)

Changing the version to SVN is unnecessary and actually unhelpful, for a couple of reasons. First, you lose the easy access to the information that the behavior has existed as far back as 1.0. Also, version being set to SVN is a possible indication of a regression: behavior that did not exist in previous released versions but exists now in trunk. Those tickets are particularly important to resolve before a release, so setting version to SVN for behavior that has existed since forever is counter-productive for the release team.

Replying to kmtracey: My bad. Thanks for the detailed explanation.