from django.db import models from geography.models import ZipCode class Restaurant(models.Model): # ... zip_code = models.ForeignKey( ZipCode, on_delete=models.SET_NULL, blank=True, null=True, )
Here is what the above code is Doing:
1. We’re importing the ZipCode model from the geography app.
2. We’re adding a ForeignKey field to the Restaurant model.
3. We’re setting the on_delete argument to models.SET_NULL. This means that if the ZipCode instance that the Restaurant is related to is deleted, the Restaurant instance will be set to null.
4. We’re setting blank=True and null=True. This means that the field can be left blank and it can be set to null.