Django的TemplateResponse

def my_render_callback(response):
	return response

from django.template.response import TemplateResponse
def my_templateresponse(request):
	response =  TemplateResponse(request, 'template.html', {})
	response.add_post_render_callback(my_render_callback);
	return response

we call add_post_render_callback to register a callback function.

in base.py , get_response 

                if hasattr(response, 'render') and callable(response.render):
                    for middleware_method in self._template_response_middleware:
                        response = middleware_method(request, response)
                    response = response.render()

The response is a TemplateResponse, the subclass of  SimpleTemplateResponse

it has a 'render' function

    def render(self):
        """Renders (thereby finalizing) the content of the response.

        If the content has already been rendered, this is a no-op.

        Returns the baked response instance.
        """
        retval = self
        if not self._is_rendered:
            self.content = self.rendered_content
            for post_callback in self._post_render_callbacks:
                newretval = post_callback(retval)
                if newretval is not None:
                    retval = newretval
        return retval

需要注意的是这个callback的返回值, 如果 not None, 它的返回值就是我们最后的response,