code: def get_qset(self, queryset, q):
          
          if self.mongoadmin.search_fields and q:
              params = {}
              for field in self.mongoadmin.search_fields:
                  if field == 'id':
                      # check to make sure this is a valid ID, otherwise we just continue
                      if is_valid_object_id(q):
                          return queryset.filter(pk=q)
                      continue
                  search_key = "{field}__icontains".format(field=field)
                  params[search_key] = q
  
              queryset = queryset.filter(**params)
          return queryset
docs: Performs filtering against the default queryset returned by
              mongoengine.