Alerts panel: Only process HTML responses

Closes #1959

debug_toolbar/middleware.py

@@ -11,9 +11,7 @@
 
 from debug_toolbar import settings as dt_settings
 from debug_toolbar.toolbar import DebugToolbar
-from debug_toolbar.utils import clear_stack_trace_caches
-
-_HTML_TYPES = ("text/html", "application/xhtml+xml")
+from debug_toolbar.utils import clear_stack_trace_caches, is_processable_html_response
 
 
 def show_toolbar(request):
@@ -102,13 +100,7 @@ def __call__(self, request):
             response.headers[header] = value
 
         # Check for responses where the toolbar can't be inserted.
-        content_encoding = response.get("Content-Encoding", "")
-        content_type = response.get("Content-Type", "").split(";")[0]
-        if (
-            getattr(response, "streaming", False)
-            or content_encoding != ""
-            or content_type not in _HTML_TYPES
-        ):
+        if not is_processable_html_response(response):
             return response
 
         # Insert the toolbar in the response.

debug_toolbar/panels/alerts.py

@@ -3,6 +3,7 @@
 from django.utils.translation import gettext_lazy as _
 
 from debug_toolbar.panels import Panel
+from debug_toolbar.utils import is_processable_html_response
 
 
 class FormParser(HTMLParser):
@@ -138,8 +139,7 @@ def check_invalid_file_form_configuration(self, html_content):
         return self.alerts
 
     def generate_stats(self, request, response):
-        # check if streaming response
-        if getattr(response, "streaming", True):
+        if not is_processable_html_response(response):
             return
 
         html_content = response.content.decode(response.charset)

debug_toolbar/utils.py

@@ -353,3 +353,16 @@ def get_stack_trace(*, skip=0):
 def clear_stack_trace_caches():
     if hasattr(_local_data, "stack_trace_recorder"):
         del _local_data.stack_trace_recorder
+
+
+_HTML_TYPES = ("text/html", "application/xhtml+xml")
+
+
+def is_processable_html_response(response):
+    content_encoding = response.get("Content-Encoding", "")
+    content_type = response.get("Content-Type", "").split(";")[0]
+    return (
+        not getattr(response, "streaming", False)
+        and content_encoding == ""
+        and content_type in _HTML_TYPES
+    )

docs/changes.rst

@@ -6,6 +6,7 @@ Pending
 
 * Changed ordering (and grammatical number) of panels and their titles in
   documentation to match actual panel ordering and titles.
+* Skipped processing the alerts panel when response isn't a HTML response.
 
 4.4.5 (2024-07-05)
 ------------------