如何访问Django-CMS插件的父模型

当我保存子插件时,我想访问父插件的模型.

from cms.plugin_pool import plugin_pool
from cms.plugin_base import CMSPluginBase

from .models import Container,Content

class ContainerPlugin(CMSPluginBase):
    model = Container
    name = "Foo Container"
    render_template = "my_package/container.html"
    allow_children = True
    child_classes = ["ContentPlugin"]

class ContentPlugin(CMSPluginBase):
    model = content
    name = "Bar Content"
    render_template = "my_package/content.html"
    require_parent = True
    parent_classes = ["ContainerPlugin"]
    allow_children = True

    def save_model(self,request,obj,form,change):
        response = super(ContentPlugin,self).save_model(
            request,change
        )

        # here I want to access the parent's (container) model,but how?

        return response

plugin_pool.register_plugin(ContainerPlugin)
plugin_pool.register_plugin(ContentPlugin)

obj是当前的插件实例,所以我可以获得这个模型的所有属性,但我无法弄清楚如何访问父插件模型.有obj.parent,但据我所知,它不是插件实例.还尝试使用self.cms_plugin_instance和obj.parent.get_plugin_instance(),但没有成功.

有什么建议？