Compress Exempt Decorator

compression_middleware/decorators.py

@@ -2,8 +2,9 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-__all__ = ['compress_page']
+__all__ = ['compress_page', 'compress_exempt']
 
+from functools import wraps
 
 from .middleware import CompressionMiddleware
 from django.utils.decorators import decorator_from_middleware
@@ -12,3 +13,12 @@
 compress_page = decorator_from_middleware(CompressionMiddleware)
 compress_page.__doc__ = "Decorator to compress the view response if the client supports it."
 
+def compress_exempt(view_func):
+    """Prevent a view from being compressed by the middleware."""
+    @wraps(view_func)
+    def _wrapped_view_func(request, *args, **kwargs):
+        # request.compress_exempt = True
+        response = view_func(request, *args, **kwargs)
+        return response
+
+    return _wrapped_view_func

compression_middleware/middleware.py

@@ -95,9 +95,11 @@ def process_response(self, request, response):
         # Test a few things before we even try:
         #  - content is already encoded
         #  - really short responses are not worth it
-        if \
-                response.has_header('Content-Encoding') or \
-                (not response.streaming and len(response.content) < MIN_LEN):
+        if (
+            response.has_header('Content-Encoding') or
+            (not response.streaming and len(response.content) < MIN_LEN) or
+            getattr(request, "compress_exempt", False) is True
+        ):
             return response
 
         patch_vary_headers(response, ('Accept-Encoding',))

tests/test_decorator.py

@@ -3,10 +3,10 @@
 
 import brotli
 
-from django.http import HttpRequest, HttpResponse, StreamingHttpResponse
-from django.test import RequestFactory, SimpleTestCase, TestCase
+from django.http import HttpResponse, StreamingHttpResponse
+from django.test import RequestFactory, SimpleTestCase
 
-from compression_middleware.decorators import compress_page
+from compression_middleware.decorators import compress_page, compress_exempt
 
 
 class CompressPageDecoratorTest(SimpleTestCase):
@@ -49,6 +49,16 @@ def a_view(request):
         self.assertEqual(r.get('Content-Length'), str(len(r.content)))
         self.assertTrue(brotli.decompress(r.content), self.compressible_string)
 
+    def test_exempt_page(self):
+
+        @compress_exempt
+        def exempt_view(request):
+            return self.resp
+
+        r = exempt_view(self.req)
+        self.assertFalse(r.has_header('Content-Encoding'))
+        self.assertEqual(r.content, self.resp.content)
+
     def test_streaming_page(self):
         @compress_page
         def a_streaming_view(request):