DateTime WTForms field that assumes input is in local time and converts to UTC for storage

datetime-local.py

# Requires Arrow package

class DateTimeWidget:
    """Widget for DateTimeFields using separate date and time inputs."""
    def __call__(self, field, **kwargs):
        id = kwargs.pop('id', field.id)
        date = time = ''
        if field.data:
            dt = arrow.get(field.data).to(current_app.config['TIMEZONE'])
            date = dt.format('YYYY-MM-DD')
            time = dt.format('HH:mm:ss')
        date_params = html_params(name=field.name, id=id + '-date', value=date, **kwargs)
        time_params = html_params(name=field.name, id=id + '-time', value=time, **kwargs)
        return HTMLString('<input type="date" {}/><input type="time" {}/>'.format(date_params, time_params))


class DateTimeLocalField(DateTimeField):
    """
    DateTimeField that assumes input is in app-configured timezone and converts
    to UTC for further processing/storage.
    """
    widget = DateTimeWidget()

    def process_formdata(self, valuelist):
        current_app.logger.debug(valuelist)
        if valuelist:
            date_str = ' '.join(valuelist)
            try:
                self.data = arrow.get(date_str).replace(tzinfo=current_app.config['TIMEZONE']).to('UTC')
            except arrow.parser.ParserError as e:
                current_app.logger.warn('Invalid datetime value submitted: %s', e)
                raise ValueError('Not a valid datetime value. Looking for YYYY-MM-DD HH:mm.')

Wow, this worked perfectly. I hope you don't mind if I use it! thank you