Queryset calculated field

Alec Meyer

This code creates a Django Model that counts the number of tasks scheduled for a specific day. It then annotates this model so that it can be searched and filtered.

from django.db.models import Count

controls = ConMonControl.objects.annotate(
  task_count=Count('scheduled_tasks')
).annotate(
  has_tasks=models.Case(
    models.When(task_count__gt=0, then=True),
    default=False,
    output_field=models.BooleanField()
  )
)