访问 Django 模型中的 ForeignKey 实例字段

Question

I'm having trouble visualizing a database query I want to run in Django. Let's say I have a couple simple models defined:

class Pizza(models.Model):
    name = models.CharField()
    ...

class Topping(models.Model):
    pizza = models.ForeignKey('pizza')
    # Get the name of pizza here

EDIT: I need to access the name in another field, not in an instance method. Is this possible?

I currently don't know how to do this. I've tried

pizza.name

But it doesn't work. Any ideas would be greatly appreciated.

Answer 1

To get a related field value, you need a model instance, Topping class instance in your case. For example, you can have a custom method defined on the Topping class:

class Topping(models.Model):
    pizza = models.ForeignKey('pizza')

    def get_pizza_name(self):
        return self.pizza.name

self here refers to a class instance.

Example usage:

topping = Topping.objects.get(pk=1)
print topping.get_pizza_name()

Answer 2

simply:

topping = Topping.objects.get(pk=1)
print(topping.pizza.name)