django-polymorphic按子类型过滤 [英] django-polymorphic Filter by child type

问题描述

我的模型结构如下:

class MyObject(PolymorphicModel):
    group = models.ForeignKey(Group)

class Group(PolymorphicModel):
    pass

class SpecialGroup(Group):
    pass

现在，我想选择所有MyObjects，该组的类型为SpecialGroup.

Now, I would like to select all MyObjects, which group is of type SpecialGroup.

是否可以在不运行原始SQL的情况下使用QuerySet API实现它? 我想到的唯一可行的解​​决方案是使用.extra()运行附加的选择" SQL查询.

Is it possible to achieve it with QuerySet API, without running raw SQL? The only working solution I came up with was by running additional 'select' SQL query using .extra().

预先感谢， 干杯！

推荐答案

在内部，django_polymorphic使用Django的ContentType框架来确定用于每个模型的实际类.

Internally, django_polymorphic uses Django's ContentType framework to determine the actual class used for each model.

from django.contrib.contenttypes.models import ContentType

MyObject.objects.filter(group__polymorphic_ctype=ContentType.objects.get_for_model(SpecialGroup))

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