title: Custom django widget - decompress() arg not populated
body: <p>As an exercise I am trying to create a custom django widget for a 24 hour clock. The widget will is a MultiWidget - a select box for each field.</p>
  
  <p>I am trying to follow docs online (kinda sparse) and looking at the Pro Django book, but I can't seem to figure it out. Am I on the right track? I can save my data from the form, but when I prepopulate the form, the form doesn't have the previous values. </p>
  
  <p>It seems the issue is that the decompress() methods 'value' argument is always empty, so I have nothing to interpret.</p>
  
  <pre><code>from django.forms import widgets
  
  import datetime
  
  class MilitaryTimeWidget(widgets.MultiWidget):
      """
      A widget that displays 24 hours time selection.
      """
      def __init__(self, attrs=None):
          hours = [ (i, "%02d" %(i)) for i in range(0, 24) ]
          minutes = [ (i, "%02d" %(i)) for i in range(0, 60) ]
          _widgets = (
              widgets.Select(attrs=attrs, choices=hours), 
              widgets.Select(attrs=attrs, choices=minutes),
              )
          super(MilitaryTimeWidget, self).__init__(_widgets, attrs)
  
      def decompress(self, value):
          print "******** %s" %value
          if value:
              return [int(value.hour), int(value.minute)]
          return [None, None]
  
      def value_from_datadict(self, data, files, name):
          hour = data.get("%s_0" %name, None)
          minute = data.get("%s_1" %name, None)
          if hour and minute:
              hour = int(hour)
              minute = int(minute)
              return datetime.time(hour=hour, minute=minute)
          return None
  </code></pre>
  
  <p>In my form, I am calling the widget like:</p>
  
  <pre><code>arrival_time = forms.TimeField(label="Arrival Time", required=False, widget=MilitaryTimeWidget())
  </code></pre>