import sys
 import json
 import urllib2
 from datetime import datetime
 from django.conf import settings
 from django.core.exceptions import ValidationError
 from streetparty.models import StrassenFest

 class StrassenFestHelper():
     def update(self):
         req = urllib2.Request(settings.STREETPARTY_DATA_URL)
         opener = urllib2.build_opener()
         source = opener.open(req)
         StrassenFest.objects.all().delete()

         for data in json.load(source)['index']:
             data['von'] = datetime.strptime(data['von'], '%Y-%m-%d')
             data['bis'] = datetime.strptime(data['bis'], '%d.%m.%Y')
             data['api_id'] = data.pop('id')
             fest = StrassenFest(**data)
             try:
                 fest.full_clean()
             except ValidationError as e:
                 print >>sys.stderr, 'Failed to validate remote entry with id %s' % data['id']
                 print >>sys.stderr, str(e)
             else:
                 fest.save()