这些实现之间有什么区别？ Django 有何不同（除了继承 Metaordering and get_latest_by属性） ？

1.

# models.py
from django.db import models

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

class Restaurant(models.Model):
    place = models.OneToOneField(Place)
    serves_pizza = models.BooleanField()

2.

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

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

3.

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

class Restaurant(Place):
    place = models.OneToOneField(Place, parent_link=True)
    serves_pizza = models.BooleanField()

1.你并没有真正获得任何Python继承，也就是说你不能从模型类继承/覆盖方法或属性Place在你的班级里Restaurant:

例如：

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

    def get_x(self):
        return 'x'

class Restaurant(models.Model):
    place = models.OneToOneField(Place)
    serves_pizza = models.BooleanField()

a_restaurant = Restaurant()
a_restaurant.get_x() # -> wouldn't work

这意味着要获得name一家你做不到的餐厅a_restaurant.name，您需要点击以下链接：a_restaurant.place.name

另请注意，查询时Place与相关的对象Restaurant.

a_restaurant.save()
Place.objects.get(pk=a_restaurant.pk)  # won't work

你必须写：

a_restaurant.save()
Place.objects.get(restaurant__pk=a_restaurant.pk)

2 and 3。几乎是一样的。你确实可以通过这些获得真正的Python继承。

a_restaurant = Restaurant()
a_restaurant.get_x() # would actually work and print 'x'

你的模特班Restaurant继承了一切Place：模型字段、普通实例/类属性、管理器、方法...您还可以覆盖几乎所有内容：您无法覆盖字段属性，这是不受支持的。

现在您可以直接从父模型获取字段的值：a_restaurant.name因为它们是遗传的。

由于通过这些实施Restaurant is a also Place你可以查询Place对象与Restaurant data:

a_restaurant.save()
the_place = Place.objects.get(pk=a_restaurant.pk)  
# ^ this works now and returns the equivalent `Place` instance.
the_same_restaurant = the_place.restaurant

The 不同之处如果您为该字段指定不同的名称，则在 2 和 3 之间更容易查看：

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

class Restaurant(Place):
    where = models.OneToOneField(Place, parent_link=True)
    serves_pizza = models.BooleanField()

工作原理完全相同，但要获取 a 的父位置Restaurant属性名称是where:

the_place = a_restaurant.where

with 2本来可以：

the_place = a_restaurant.place_ptr

这些意味着place = models.OneToOneField(Place, parent_link=True)只会更改父模型实例的链接名称。默认名称是'{lowercase_model_name}_ptr'.

最后一个例子：

With 1:

place1 = Place.objects.create(name='place_1')
place2 = Place.objects.create(name='place_2')
restaurant1 = Restaurant.objects.create(place=place1, serves_pizza=True)

print Place.objects.all() # prints [place1, place2]
print Restaurant.objects.all() # prints [restaurant1]

With 2-3:

place1 = Place.objects.create(name='place_1')
place2 = Place.objects.create(name='place_2')
restaurant1 = Restaurant.objects.create(name='place_3', serves_pizza=True)

print Place.objects.all() # prints [place1, place2, place3]
print Restaurant.objects.all() # prints [restaurant1]

希望这些有帮助。它长得有点太长了：/