patient_doctor_example.py

### models.py

from django.core.exceptions import PermissionDenied
from django.contrib.auth.models import AbstractUser
from django.db import models
from django.http import HttpResponse, Http404

# your custom user model here
class MyCustomUser(AbstractUser):
    is_patient = models.BooleanField()
    is_doctor = models.BooleanField()

class Patient(models.Model):
    # could also be a OneToOneField if the user can only have at most one patient/doctor
    user = models.ForeignKey(MyCustomUser)
 
class Doctor(models.Model):
    user = models.ForeignKey(MyCustomUser)
    patients = models.ManyToManyField(Patient)
  
### views.py

def get_patients(request):
    if not request.user.is_doctor:
        raise PermissionDenied
        
    try:
        # for simplicity's sake, we'll assume a user can only 
        # have at most one doctor. If a user can have multiple Doctor "accounts",
        # you would need to specify the one whose patients should be retrieved. 
        doctor = Doctor.objects.get(user=request.user)        
    except Doctor.DoesNotExist:
        raise Http404("Not found")
    
    patients = doctor.patients.all()
    return render(request, 'patients.html', {'patients': patients})