Fix Django 1.9 issue preventing use of MIDDLEWARE_CLASSES (open-telemetry#870)

* Update CHANGELOG.md

* Fix Django 1.9 issue preventing use of MIDDLEWARE_CLASSES

Co-authored-by: Srikanth Chekuri <[email protected]>

Author: 2 people

CHANGELOG.md

@@ -28,6 +28,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `opentelemetry-instrumentation-asgi` ASGI: Conditionally create SERVER spans
   ([#843](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/843))
 
+- `opentelemetry-instrumentation-django` Django: fix issue preventing detection of MIDDLEWARE_CLASSES
 
 ## [1.8.0-0.27b0](https://github.com/open-telemetry/opentelemetry-python/releases/tag/v1.8.0-0.27b0) - 2021-12-17
 

instrumentation/opentelemetry-instrumentation-django/src/opentelemetry/instrumentation/django/__init__.py

@@ -105,7 +105,7 @@ def _get_django_middleware_setting() -> str:
     # In Django versions 1.x, setting MIDDLEWARE_CLASSES can be used as a legacy
     # alternative to MIDDLEWARE. This is the case when `settings.MIDDLEWARE` has
     # its default value (`None`).
-    if not DJANGO_2_0 and getattr(settings, "MIDDLEWARE", []) is None:
+    if not DJANGO_2_0 and getattr(settings, "MIDDLEWARE", None) is None:
         return "MIDDLEWARE_CLASSES"
     return "MIDDLEWARE"