Bound method label on latency histogram to known HTTP methods

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * Add support for Django 6.1.
 * Drop support for Python 3.9.
+* Fold unknown HTTP methods into `<invalid method>` in `django_http_requests_latency_seconds_by_view_method`, like the other per-method metrics.
 * TBD
 
 ## v2.5.0 - May 26th, 2026

django_prometheus/middleware.py

@@ -287,7 +287,7 @@ def process_response(self, request, response):
                 request,
                 response,
                 view=self._get_view_name(request),
-                method=request.method,
+                method=self._method(request),
             ).observe(TimeSince(request.prometheus_after_middleware_event))
         else:
             self.label_metric(self.metrics.requests_unknown_latency, request, response).inc()
@@ -303,7 +303,7 @@ def process_exception(self, request, exception):
                 self.metrics.requests_latency_by_view_method,
                 request,
                 view=self._get_view_name(request),
-                method=request.method,
+                method=self._method(request),
             ).observe(TimeSince(request.prometheus_after_middleware_event))
         else:
             self.label_metric(self.metrics.requests_unknown_latency, request).inc()

django_prometheus/tests/end2end/testapp/test_middleware.py

@@ -131,6 +131,26 @@ def test_exception_latency_histograms(self, client):
             method="GET",
         )
 
+    def test_latency_histograms_bound_invalid_methods(self, client):
+        # Unknown HTTP methods are client-controlled and must be folded
+        # into "<invalid method>" for the latency histogram too, like the
+        # other per-method metrics, to keep label cardinality bounded.
+        registry = save_registry()
+        client.generic("FOOBAR", "/help")
+        assert_metric_diff(
+            registry,
+            1,
+            M("requests_latency_seconds_by_view_method_count"),
+            view="testapp.views.help",
+            method="<invalid method>",
+        )
+        assert_metric_equal(
+            None,
+            M("requests_latency_seconds_by_view_method_count"),
+            view="testapp.views.help",
+            method="FOOBAR",
+        )
+
     def test_streaming_responses(self, client):
         registry = save_registry()
         client.get("/")