django中 分别获取父类子类 对象

[code]
from django.db import models
from django.db.models.query import QuerySet


class ChildQuerySet(QuerySet):
def iterator(self):
for obj in super(ChildQuerySet, self).iterator():
yield obj.get_child_object()


class ChildManager(models.Manager):
def get_query_set(self):
return ChildQuerySet(self.model)


class ParentModel(models.Model):
_child_name = models.CharField(max_length=100, editable=False)

class Meta:
abstract = True

def save(self, *args, **kwargs):
self._child_name = self.get_child_name()
super(ParentModel, self).save(*args, **kwargs)

def get_child_name(self):
if type(self) is self.get_parent_model():
return self._child_name
return self.get_parent_link().related_query_name()

def get_child_object(self):
return getattr(self, self.get_child_name())

def get_parent_link(self):
return self._meta.parents[self.get_parent_model()]

def get_parent_model(self):
raise NotImplementedError

def get_parent_object(self):
return getattr(self, self.get_parent_link().name)

[/code]
用法：
[code]
class Post(ParentModel):
title = models.CharField(max_length=50)

objects = models.Manager()
children = ChildManager()

def __unicode__(self):
return self.title

def get_parent_model(self):
return Post

class Article(Post):
text = models.TextField()

class Photo(Post):
image = models.ImageField(upload_to='photos/')

class Link(Post):
url = models.URLField()


输出:
>>> Post.objects.all()
[, , ]

>>> Post.children.all()
[, , ]
[/code]