from django.apps import apps
from django.conf import settings
from django.contrib.redirects.models import Redirect
from django.contrib.sites.shortcuts import get_current_site
from django.core.exceptions import ImproperlyConfigured
from django.http import HttpResponseGone, HttpResponsePermanentRedirect
from django.utils.deprecation import MiddlewareMixin
class RedirectFallbackMiddleware(MiddlewareMixin):
# Defined as class-level attributes to be subclassing-friendly.
response_gone_class = HttpResponseGone
response_redirect_class = HttpResponsePermanentRedirect
def __init__(self, get_response=None):
if not apps.is_installed('django.contrib.sites'):
raise ImproperlyConfigured(
"You cannot use RedirectFallbackMiddleware when "
"django.contrib.sites is not installed."
)
super().__init__(get_response)
def process_response(self, request, response):
# No need to check for a redirect for non-404 responses.
if response.status_code != 404:
return response
full_path = request.get_full_path()
current_site = get_current_site(request)
r = None
try:
r = Redirect.objects.get(site=current_site, old_path=full_path)
except Redirect.DoesNotExist:
pass
if r is None and settings.APPEND_SLASH and not request.path.endswith('/'):
try:
r = Redirect.objects.get(
site=current_site,
old_path=request.get_full_path(force_append_slash=True),
)
except Redirect.DoesNotExist:
pass
if r is not None:
if r.new_path == '':
return self.response_gone_class()
return self.response_redirect_class(r.new_path)
# No redirect was found. Return the response.
return response