源代码

from django.http import HttpResponse
from django.utils import six

from .loader import get_template, select_template


class SimpleTemplateResponse(HttpResponse):
    rendering_attrs = ['template_name', 'context_data', '_post_render_callbacks']

    def __init__(self, template, context=None, content_type=None, status=None,
                charset=None, using=None):
    
        self.template_name = template
        self.context_data = context
        self.using = using

        self._post_render_callbacks = []
        self._request = None
        super(SimpleTemplateResponse, self).__init__('', content_type, status, charset=charset)
        self._is_rendered = False

    def resolve_template(self, template):
        # 获取模板
        if isinstance(template, (list, tuple)):
            return select_template(template, using=self.using)
        elif isinstance(template, six.string_types):
            return get_template(template, using=self.using)
        else:
            return template
    def resolve_context(self, context):
        # 获取context
        return context
    @property
    def rendered_content(self):
        # 和我在发送邮件时的处理一样
        template = self.resolve_template(self.template_name)
        context = self.resolve_context(self.context_data)
        content = template.render(context, self._request)
        return content

    def add_post_render_callback(self, callback):

        if self._is_rendered:
            callback(self)
        else:
            self._post_render_callbacks.append(callback)

    def render(self):
        
        retval = self
        if not self._is_rendered:
            self.content = self.rendered_content

            # 调用之前注册的callback
            for post_callback in self._post_render_callbacks:
                newretval = post_callback(retval)
                if newretval is not None:
                    retval = newretval

        return retval

    @property
    def is_rendered(self):
        return self._is_rendered

    def __iter__(self):
        if not self._is_rendered:
            raise ContentNotRenderedError(
                'The response content must be rendered before it can be iterated over.'
            )
        return super(SimpleTemplateResponse, self).__iter__()

    @property
    def content(self):
        if not self._is_rendered:
            raise ContentNotRenderedError(
                'The response content must be rendered before it can be accessed.'
            )
        return super(SimpleTemplateResponse, self).content

    @content.setter
    def content(self, value):
        HttpResponse.content.fset(self, value)
        self._is_rendered = True


class TemplateResponse(SimpleTemplateResponse):
    rendering_attrs = SimpleTemplateResponse.rendering_attrs + ['_request']

    def __init__(self, request, template, context=None, content_type=None,
                status=None, charset=None, using=None):
        super(TemplateResponse, self).__init__(
            template, context, content_type, status, charset, using)
        self._request = request