Django Class based models How to create a method to return number of children in foreignkey relationship

Question

Hi from all round newbie. New to this forum, new to Python and Django. Migrating from other languages.

Need some advice on how best to go about this... I have a parent-child relationship. Country table linked to Provinces(States). Would like to have the number of provinces shown when listing the Countries in a list view. Thought to create a Method in the parent that would return this. Or is there an out of the box feature in Django that does this?

class Country(models.Model):
    country_id = models.CharField(max_length=2)
    country_name = models.CharField(max_length=35)
    
    def __str__(self):
        return self.country_id
    
    def get_absolute_url(self):
        return reverse('country-detail', kwargs={'pk':self.pk})  
    
    def get_child_count(self):
        return Province.objects.filter(country_id=self.country_id)
    
    
class Province(models.Model):
    province_id = models.CharField(max_length=2)
    province_name = models.CharField(max_length=35)
    country = models.ForeignKey(Country, on_delete=models.CASCADE, related_name='provinces')    
    
    def __str__(self):
        return self.province_id

Thanks in advance.

question from:https://stackoverflow.com/questions/66061654/django-class-based-models-how-to-create-a-method-to-return-number-of-children-in

Answer 1

Waitting for answers