# Τεκμηρίωση του Django - 1.10.7

# Πηγαίος κώδικας για το django.template.response

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

    from .loader import get_template, select_template

    class ContentNotRenderedError(Exception):
        pass

    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):
            # It would seem obvious to call these next two members 'template' and
            # 'context', but those names are reserved as part of the test Client
            # API. To avoid the name collision, we use different names.
            self.template_name = template
            self.context_data = context

            self.using = using

            self._post_render_callbacks = []

            # _request stores the current request object in subclasses that know
            # about requests, like TemplateResponse. It's defined in the base class
            # to minimize code duplication.
            # It's called self._request because self.request gets overwritten by
            # django.test.client.Client. Unlike template_name and context_data,
            # _request should not be considered part of the public API.
            self._request = None

            # content argument doesn't make sense here because it will be replaced
            # with rendered template so we always pass empty string in order to
            # prevent errors and provide shorter signature.
            super(SimpleTemplateResponse, self).__init__('', content_type, status, charset)

            # _is_rendered tracks whether the template and context has been baked
            # into a final response.
            # Super __init__ doesn't know any better than to set self.content to
            # the empty string we just gave it, which wrongly sets _is_rendered
            # True, so we initialize it to False after the call to super __init__.
            self._is_rendered = False

        def __getstate__(self):
            """Pickling support function.

            Ensures that the object can't be pickled before it has been
            rendered, and that the pickled state only includes rendered
            data, not the data used to construct the response.
            """
            obj_dict = self.__dict__.copy()
            if not self._is_rendered:
                raise ContentNotRenderedError('The response content must be '
                                              'rendered before it can be pickled.')
            for attr in self.rendering_attrs:
                if attr in obj_dict:
                    del obj_dict[attr]

            return obj_dict

        def resolve_template(self, template):
            "Accepts a template object, path-to-template or list of paths"
            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):
            return context

        @property
        def rendered_content(self):
            """Returns the freshly rendered content for the template and context
            described by the TemplateResponse.

            This *does not* set the final content of the response. To set the
            response content, you must either call render(), or set the
            content explicitly using the value of this property.
            """
            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):
            """Adds a new post-rendering callback.

            If the response has already been rendered,
            invoke the callback immediately.
            """
            if self._is_rendered:
                callback(self)
            else:
                self._post_render_callbacks.append(callback)

        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

        @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):
            """Sets the content for the response
            """
            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