models.py

from django.db import models

class Country(models.Model):
    name = models.CharField(max_length=255)
    total_population = models.IntegerField()
    
class Person(models.Model):
    full_name = models.CharField(max_length=255)
    first_dose_received_on = models.DateTimeField(null=True, blank=True)
    second_dose_received_on = models.DateTimeField(null=True, blank=True)
    country = models.ForeignKey(Country, on_delete=models.CASCADE)