Need to include

Using Django Using the ORM
1

I have these models to present a location

from django.db import models

class Country(models.Model):
    name = models.CharField(max_length=50)
    country_code = models.CharField(max_length=5)
    dial_code = models.CharField(max_length=5)
    created_at = models.DateTimeField("date post was created", auto_now_add=True)
    updated_at = models.DateTimeField("date post was updated", auto_now=True)

    class Meta:
        verbose_name = "country"
        verbose_name_plural = "countries"
        db_table = "countries"
        ordering = ["name"]

class State(models.Model):
    name = models.CharField(max_length=50)
    country = models.ForeignKey(Country, on_delete=models.CASCADE, default=None)
    created_at = models.DateTimeField("date post was created", auto_now_add=True)
    updated_at = models.DateTimeField("date post was updated", auto_now=True)
    
    class Meta:
        verbose_name = "state"
        verbose_name_plural = "states"
        db_table = "states"
        ordering = ["name"]

class City(models.Model):
    name = models.CharField(max_length=50)
    country = models.ForeignKey(Country, on_delete=models.CASCADE, default=None)
    state = models.ForeignKey(State, on_delete=models.CASCADE, default=None)
    created_at = models.DateTimeField("date post was created", auto_now_add=True)
    updated_at = models.DateTimeField("date post was updated", auto_now=True)
    
    class Meta:
        verbose_name = "city"
        verbose_name_plural = "cities"
        db_table = "cities"
        ordering = ["name"]

class Location(models.Model):
    street = models.CharField(max_length=100)
    additional = models.CharField(max_length=100)
    zip = models.CharField(max_length=20)
    country = models.ForeignKey(Country, on_delete=models.CASCADE, default=None)
    state = models.ForeignKey(State, on_delete=models.CASCADE, default=None)
    city = models.ForeignKey(City, on_delete=models.CASCADE, default=None)
    phone = models.CharField(max_length=15)

    created_at = models.DateTimeField(auto_now_add=True, verbose_name="created at")
    updated_at = models.DateTimeField(auto_now=True, verbose_name="updated at")
    
    class Meta:
        verbose_name = "location"
        verbose_name_plural = "locations"
        db_table = "locations"
        ordering = ["zip"]

I would like to know if I need the foreign key references fore country and state in the location class? Cities have a foreign key to states and states have a foreign key to countries. So if I just have cities in the location class then surely I can get the state and the country from the city not?

Advice is really appreciated

2

You are correct. You can chain foreign key references together in queries, templates, and other code referencing model instances. So all those extra foreign key fields are unnecessary.

3

Thank you Ken appreciate the advice