class Model(models.Model):
    created = models.DateTimeField(auto_now_add=True, auto_now=False, verbose_name='Created')
    updated = models.DateTimeField(auto_now_add=False, auto_now=True, verbose_name='Updated')
    @property
    def _approved(self):
        return ModelRecordRelation.objects.filter(model_id=self.id, status='A').count()

class TimeFrameFilter(SimpleListFilter):
    title = 'timeframe'
    parameter_name = 'timeframe'
    def lookups(self, request, model_admin):
        return [
            ('Today', 'Today'),
            ('ThisWeek', 'This Week'),
        ]
    def queryset(self, request, queryset):
        return queryset.filter()
class ModelAdmin(admin.ModelAdmin):
    list_display = ['created', 'updated']
    class Meta:
        model = Model
    def approved(self, obj):
        return obj._approved
    approved.admin_order_field = 'approved'

class ModelAdmin(admin.ModelAdmin):
    list_display = ['created', 'updated', 'approved']
    list_filter = [TimeFrameFilter]
    def get_queryset(self, request):
        queryset = super().get_queryset(request)
        queryset = queryset.annotate(approved_count=Count('modelrecordrelation', filter=models.Q(modelrecordrelation__status='A')))
        return queryset
    def approved(self, obj):
        return obj.approved_count
    approved.admin_order_field = 'approved_count'