def get_queryset(self):
        # current_date = datetime(2024, 9, 2, 12, 56, 54, 324893).today()
        current_date = datetime.today()

        # get the booking data from the current date  --------- requested_datetime is when the patient has scheduled the booking for 
        booking_data = PatientBooking.objects.annotate(
            admission_datetime=F('requested_admission_datetime'),
            delivery_datetime=F('estimated_due_date'),
            fully_dilation_datetime=ExpressionWrapper(
                F('estimated_due_date') - timedelta(days=(1)), 
                output_field=DateTimeField()
            ),
            source=Value('booking', output_field=CharField())
        ).filter(status="ACCEPTED", 
                 admission_datetime__date=current_date
                )

        # get the patient data from the current date ---- based on when the patient record is created_at
        patient_data = PatientDetails.objects.annotate(
            admission_datetime=F('created_at'),
            delivery_datetime=F('estimated_due_date'),
            fully_dilation_datetime=F('patient_fully_dilated'),
            source=Value('patient', output_field=CharField())
        ).filter(status="ACTIVE",
                admission_datetime__date=current_date
            )

        # combine the record in one queryset using union on the required fields only
        combined_queryset = booking_data.values('first_name', 'last_name', 'delivery_type', 'date_of_birth',
            'admission_datetime', 'delivery_datetime', 'fully_dilation_datetime', 'source'
        ).union(
            patient_data.values('first_name', 'last_name', 'delivery_type', 'date_of_birth',
                'admission_datetime', 'delivery_datetime', 'fully_dilation_datetime', 'source'
            )
        ).order_by('first_name', 'last_name', 'date_of_birth')

        # if records in both the model matches---- then consider it as same patient and consider the record where the source=patient
        combined_queryset = combined_queryset.distinct(
            'first_name', 'last_name', 'date_of_birth'
        )
        return combined_queryset

This is my queryset. I have two models PatientDetails and PatientBooking both models have different numbers of fields and names I want to get a single queryset with specific fields from both tables.
So I first annotate the field name and then perform union to it. To get a single queryset with field name (‘first_name’, ‘last_name’, ‘delivery_type’, ‘date_of_birth’,
‘admission_datetime’, ‘delivery_datetime’, ‘fully_dilation_datetime’, ‘source’) . Till now everything is working fine and I’m getting the desired result.

But after getting the result from both the models in a single queryset . Now I want to get distinct record based on (‘first_name’, ‘last_name’,’date_of_birth’)
I tried

combined_queryset = combined_queryset.distinct(
            'first_name', 'last_name', 'date_of_birth'
        )

but it is not working.
What I’m doing wrong can anyone tell me.