4
class Topping(models.Model):
name = models.CharField(max_length=30)
class Pizza(models.Model):
name = models.CharField(max_length=50)
toppings = models.ManyToManyField(Topping)
是否可以选择比萨饼和他们的浇头,但只有那些比萨饼,有一定数量的浇头,如0,1,2?在django中过滤prefetch_related空