code: def set_preferences(request, dashboard_id):
      
      try:
          preferences = DashboardPreferences.objects.get(
              user=request.user,
              dashboard_id=dashboard_id
          )
      except DashboardPreferences.DoesNotExist:
          preferences = None
      if request.method == "POST":
          form = DashboardPreferencesForm(
              user=request.user,
              dashboard_id=dashboard_id,
              data=request.POST,
              instance=preferences
          )
          if form.is_valid():
              preferences = form.save()
              if request.is_ajax():
                  return HttpResponse('true')
              messages.success(request, 'Preferences saved')
          elif request.is_ajax():
              return HttpResponse('false')
      else:
          form = DashboardPreferencesForm(
              user=request.user,
              dashboard_id=dashboard_id,
              instance=preferences
          )
      return render_to_response(
          'admin_tools/dashboard/preferences_form.html',
           {'form': form}
      )
docs: This view serves and validates a preferences form.