Refs #26601 -- Deprecated passing None as get_response arg to middleware classes.

This is the new contract since middleware refactoring in Django 1.10.

Co-authored-by: Carlton Gibson <carlton.gibson@noumenal.es>
Co-authored-by: Mariusz Felisiak <felisiak.mariusz@gmail.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/django/utils/deprecation.py b/django/utils/deprecation.py
index 6599cd2e83..81e7c3a15b 100644
--- a/django/utils/deprecation.py
+++ b/django/utils/deprecation.py
@@ -80,7 +80,10 @@ class DeprecationInstanceCheck(type):
 
 
 class MiddlewareMixin:
+    # RemovedInDjango40Warning: when the deprecation ends, replace with:
+    #   def __init__(self, get_response):
     def __init__(self, get_response=None):
+        self._get_response_none_deprecation(get_response)
         self.get_response = get_response
         super().__init__()
 
@@ -92,3 +95,11 @@ class MiddlewareMixin:
         if hasattr(self, 'process_response'):
             response = self.process_response(request, response)
         return response
+
+    def _get_response_none_deprecation(self, get_response):
+        if get_response is None:
+            warnings.warn(
+                'Passing None for the middleware get_response argument is '
+                'deprecated.',
+                RemovedInDjango40Warning, stacklevel=3,
+            )