How to sort a column by Django model method using django-sortable-listview (SortableListView)?

[Nancy Jenifer Benita S]

Using django-sortable-listview package, I'm using SortableListView to sort out all the model fields. In my case, more than model fields, I want to sort it out by model method too.

 

Models.py

class Employee(models.Model):

      name = models.CharField()

      designation = models.CharField()

      company = models.ForeignKey(Company)

      team = models.CharField()

      

      # method

      def team_count(self):

        count = len(Employee.objects.filter(team=self.team))

        return count

Views.py 

class EmployeeListView(SortableListView, generic.list.ListView):

    allowed_sort_fields = {'name': {'default_direction': '', 'verbose_name': 'Employee Name'},

                           'designation': {'default_direction': '', 'verbose_name': 'Designation'},

                           'team': {'default_direction': '', 'verbose_name': 'Team Name'},

                           'team_count()': {'default_direction': '', 'verbose_name': 'No of Team members'}}

    default_sort_field = 'name'

    queryset = Employee.objects.all()

    paginate_by = 10

On the above example, I want to list out Employee name, designation, team name and count of team members.

Anybody help me to sort 'team_count' column?