Bugfix: ModuleNotFoundError 'No module named django.core.urlresolvers…

.gitignore

@@ -4,3 +4,12 @@
 build/
 dist/
 pip-log.txt
+venv/*
+# Editor directories and files
+.idea
+.vscode
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?

subdomains/middleware.py

@@ -7,17 +7,22 @@
 
 from subdomains.utils import get_domain
 
-
 logger = logging.getLogger(__name__)
 lower = operator.methodcaller('lower')
 
 UNSET = object()
 
+try:
+    from django.utils.deprecation import MiddlewareMixin
+except:
+    MiddlewareMixin = object
+
 
-class SubdomainMiddleware(object):
+class SubdomainMiddleware(MiddlewareMixin):
     """
     A middleware class that adds a ``subdomain`` attribute to the current request.
     """
+
     def get_domain_for_request(self, request):
         """
         Returns the domain that will be used to identify the subdomain part
@@ -30,7 +35,7 @@ def process_request(self, request):
         Adds a ``subdomain`` attribute to the ``request`` parameter.
         """
         domain, host = map(lower,
-            (self.get_domain_for_request(request), request.get_host()))
+                           (self.get_domain_for_request(request), request.get_host()))
 
         pattern = r'^(?:(?P<subdomain>.*?)\.)?%s(?::.*)?$' % re.escape(domain)
         matches = re.match(pattern, host)
@@ -40,14 +45,15 @@ def process_request(self, request):
         else:
             request.subdomain = None
             logger.warning('The host %s does not belong to the domain %s, '
-                'unable to identify the subdomain for this request',
-                request.get_host(), domain)
+                           'unable to identify the subdomain for this request',
+                           request.get_host(), domain)
 
 
 class SubdomainURLRoutingMiddleware(SubdomainMiddleware):
     """
     A middleware class that allows for subdomain-based URL routing.
     """
+
     def process_request(self, request):
         """
         Sets the current request's ``urlconf`` attribute to the urlconf
@@ -62,7 +68,7 @@ def process_request(self, request):
             urlconf = settings.SUBDOMAIN_URLCONFS.get(subdomain)
             if urlconf is not None:
                 logger.debug("Using urlconf %s for subdomain: %s",
-                    repr(urlconf), repr(subdomain))
+                             repr(urlconf), repr(subdomain))
                 request.urlconf = urlconf
 
     def process_response(self, request, response):

subdomains/tests/tests.py

@@ -6,7 +6,7 @@
 except ImportError:  # Python 3
     from urllib import parse as urlparse
 
-from django.core.urlresolvers import NoReverseMatch, set_urlconf
+from django.urls import NoReverseMatch, set_urlconf
 from django.template import Context, Template
 from django.test import TestCase
 from django.test.client import RequestFactory

subdomains/utils.py

@@ -5,7 +5,7 @@
     from urllib.parse import urlunparse
 
 from django.conf import settings
-from django.core.urlresolvers import reverse as simple_reverse
+from django.urls import reverse as simple_reverse
 
 
 def current_site_domain():