Fix MultipleObjectsReturned error when multiple integrations exist (#12581)

Fixes a error that occurs when a project has multiple integrations with
the same .

## Changes

Modified  method in  to:
- Check the count of matching integrations
- Raise a clear  (400 Bad Request) when multiple integrations are found
- Provide an actionable error message directing users to use the webhook
URL specific to their integration

## References

* Sentry issue: https://read-the-docs.sentry.io/issues/4951512277/
* Related issue:
#11037

---
*Generated by Copilot*

---------

Co-authored-by: Copilot <198982749+Copilot@users.noreply.github.com>

Author: ericholscher

readthedocs/api/v2/views/integrations.py

@@ -7,6 +7,7 @@
 from textwrap import dedent
 
 import structlog
+from django.http import Http404
 from django.shortcuts import get_object_or_404
 from django.utils.crypto import constant_time_compare
 from rest_framework import permissions
@@ -152,12 +153,20 @@ def finalize_response(self, req, *args, **kwargs):
         """If the project was set on POST, store an HTTP exchange."""
         resp = super().finalize_response(req, *args, **kwargs)
         if hasattr(self, "project") and self.project:
-            HttpExchange.objects.from_exchange(
-                req,
-                resp,
-                related_object=self.get_integration(),
-                payload=self.data,
-            )
+            try:
+                integration = self.get_integration()
+            except (Http404, ParseError):
+                # If we can't get a single integration (either none or multiple exist),
+                # we can't store the HTTP exchange
+                integration = None
+
+            if integration:
+                HttpExchange.objects.from_exchange(
+                    req,
+                    resp,
+                    related_object=integration,
+                    payload=self.data,
+                )
         return resp
 
     def get_data(self):
@@ -203,11 +212,21 @@ def get_integration(self):
         # in `WebhookView`
         if self.integration is not None:
             return self.integration
-        self.integration = get_object_or_404(
-            Integration,
+
+        integrations = Integration.objects.filter(
             project=self.project,
             integration_type=self.integration_type,
         )
+
+        if not integrations.exists():
+            raise Http404("No Integration matches the given query.")
+        elif integrations.count() > 1:
+            raise ParseError(
+                "Multiple integrations found for this project. "
+                "Please use the webhook URL with an explicit integration ID."
+            )
+
+        self.integration = integrations.first()
         return self.integration
 
     def get_response_push(self, project, versions_info: list[VersionInfo]):

readthedocs/rtd_tests/tests/test_api.py

@@ -3502,6 +3502,35 @@ def test_dont_allow_webhooks_without_a_secret(self, trigger_build):
         # and return a 400 if it doesn't.
         self.assertEqual(resp.status_code, 404)
 
+    def test_multiple_integrations_error(self, trigger_build):
+        """Test that multiple integrations with same type returns a 400 error."""
+        client = APIClient()
+
+        # Create a second GitHub integration for the same project with the same secret
+        secret = self.github_integration.secret
+        Integration.objects.create(
+            project=self.project,
+            integration_type=Integration.GITHUB_WEBHOOK,
+            secret=secret,
+        )
+
+        # Now there are two integrations, so the webhook should return a 400 error
+        payload = {"ref": "refs/heads/master"}
+        signature = get_signature(self.github_integration, payload)
+
+        resp = client.post(
+            f"/api/v2/webhook/github/{self.project.slug}/",
+            payload,
+            format="json",
+            headers={
+                GITHUB_SIGNATURE_HEADER: signature,
+            },
+        )
+
+        # Should return 400 Bad Request
+        self.assertEqual(resp.status_code, 400)
+        self.assertIn("Multiple integrations found", resp.data["detail"])
+
 
 @override_settings(PUBLIC_DOMAIN="readthedocs.io")
 class APIVersionTests(TestCase):