Django 模型继承:使用现有的超类创建子类 [英] Django model inheritance: Create a subclass using existing super class

问题描述

我正在使用 多表继承，并想知道如何从超类的实例创建继承类型.

I'm using multi-table-inheritance, and want to know how to create an inherited type from an instance of the superclass.

使用文档中给出的示例:

Using the example given in the documentation:

class Place(models.Model):
    name = models.CharField(max_length=50)
    address = models.CharField(max_length=80)

class Restaurant(Place):
    serves_hot_dogs = models.BooleanField()
    serves_pizza = models.BooleanField()

现在当你创建一个 Restaurant 时，你会自动创建一个 Place，这很好，也是我期望和想要的行为.

Now when you create a Restaurant, you automatically make a Place, which is fine, and the behaviour I expect and want.

但是，如果我创建了一个 Place，然后我决定要转换为特定类型(例如 Restaurant)，该怎么办?如何使用现有的 Place 创建 Restaurant?

But what if I make a Place, and later decide I want to convert to a specific type (like Restaurant). How do you create a Restaurant, using an existing Place?

推荐答案

多表继承只是 Place 和 Restaurant 之间的 OneToOneField 关系.

Multi-table inheritance is just OneToOneField relation between Place and Restaurant.

place = Place.objects.get(id=1)               

# Create a restaurant using existing Place   
restaurant = Resturant(place_ptr=place)
restaurant.save()

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