A snippet of my Backend Django work for NeedOne, a mobile Android and iOS application which alerts network when a particular user needs participants for an activity (ie a sports game, workout, meetup, meal).

gistfile1.txt

#From event_api.py: 
def create_event(author, place, scope, event_type, start_time, how_many):
    newPlace = Place.objects.get(name=place)
    event, created = Event.objects.get_or_create(author=author, place=newPlace, scope=scope, event_type=event_type, start_time=start_time,     how_many = how_many, defaults={'status':0})
    return event
    
def record_invites(event, invitees):
    new_invitees = json.loads(invitees)
    for invitee in new_invitees:
        user = Profile.objects.get(user__username=invitee)
        invitee_count = Profile.objects.filter(user=user)
        if invitee_count > 0:
            new_invite, created = Invite.objects.get_or_create(event=event, invitee=user)
        else:
            raise ValidationError("Invitee " + str(invitee) + " does not exist")
            
def record_rsvp(event, user_profile):
    user_profile_id = user_profile.id
    profile_object_user = Profile.objects.get(id=user_profile_id)
    event_id = Event.objects.get(id=event)
    added_RSVP, created = RSVP.objects.get_or_create(event = event_id, user_profile = profile_object_user)
    return added_RSVP
    
#from event_views.py
class CreateEvent(View):
    def post(self, request):
        try:
            place = request.POST.get('place')
            scope = models.PUBLIC
            event_type = request.POST.get('event_type')
            start_time = request.POST.get('start_time')
            author = request.user_profile
            start_time = datetime.datetime.fromtimestamp(int(float(start_time)))
            how_many = request.POST.get('how_many')
            invitees = request.POST.get('invitees')
            validate_input(author, scope, event_type, start_time)
            new_event = create_event(author, place, scope, event_type, start_time, how_many)
            return JsonResponse({'success': True, 'message': "Event created"})
            
        except ValidationError as e:
            return JsonResponse({'success': False, 'message': str(e)})

class SubmitRSVP(View):
    def post(self, request):
        try:
            user = request.user_profile
            event = request.POST.get('event')
            rsvp = record_rsvp(event, user)
            return JsonResponse({'success': True, 'message': "RSVP submitted"})
            
        except ValidationError as f:
            return JsonResponse({'success': False, 'message': str(f)})