From 71620d323f42c99367efe4a192c70819107868a7 Mon Sep 17 00:00:00 2001
From: d0cd <23022326+d0cd@users.noreply.github.com>
Date: Tue, 28 Apr 2026 14:46:53 +0000
Subject: [PATCH] perf: eliminate N+1 queries in IssueSerializer and dedupe
 cycle conflict check

- IssueSerializer.to_representation now reads assignees/labels from the
  existing prefetched M2M cache instead of issuing fresh IssueAssignee /
  IssueLabel filter queries per instance. The view's get_queryset already
  prefetches both relations, so every issue serialized in a list endpoint
  was wasting up to 4 extra queries.

- CycleListCreate.post collapses the duplicate "exists check then refetch"
  pair into a single .first() lookup.

Run-on: Niteshift Staging

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
---
 apps/api/plane/api/serializers/issue.py | 25 ++++++------------------
 apps/api/plane/api/views/cycle.py       | 26 +++++++++----------------
 2 files changed, 15 insertions(+), 36 deletions(-)

diff --git a/apps/api/plane/api/serializers/issue.py b/apps/api/plane/api/serializers/issue.py
index ba9ddae301d..430706f8cf8 100644
--- a/apps/api/plane/api/serializers/issue.py
+++ b/apps/api/plane/api/serializers/issue.py
@@ -289,32 +289,19 @@ def update(self, instance, validated_data):
     def to_representation(self, instance):
         data = super().to_representation(instance)
         if "assignees" in self.fields:
+            assignees = instance.assignees.all()
             if "assignees" in self.expand:
                 from .user import UserLiteSerializer
 
-                data["assignees"] = UserLiteSerializer(
-                    User.objects.filter(
-                        pk__in=IssueAssignee.objects.filter(issue=instance).values_list("assignee_id", flat=True)
-                    ),
-                    many=True,
-                ).data
+                data["assignees"] = UserLiteSerializer(assignees, many=True).data
             else:
-                data["assignees"] = [
-                    str(assignee)
-                    for assignee in IssueAssignee.objects.filter(issue=instance).values_list("assignee_id", flat=True)
-                ]
+                data["assignees"] = [str(assignee.id) for assignee in assignees]
         if "labels" in self.fields:
+            labels = instance.labels.all()
             if "labels" in self.expand:
-                data["labels"] = LabelSerializer(
-                    Label.objects.filter(
-                        pk__in=IssueLabel.objects.filter(issue=instance).values_list("label_id", flat=True)
-                    ),
-                    many=True,
-                ).data
+                data["labels"] = LabelSerializer(labels, many=True).data
             else:
-                data["labels"] = [
-                    str(label) for label in IssueLabel.objects.filter(issue=instance).values_list("label_id", flat=True)
-                ]
+                data["labels"] = [str(label.id) for label in labels]
 
         return data
 
diff --git a/apps/api/plane/api/views/cycle.py b/apps/api/plane/api/views/cycle.py
index 30b04ed46dd..06f102acd62 100644
--- a/apps/api/plane/api/views/cycle.py
+++ b/apps/api/plane/api/views/cycle.py
@@ -307,29 +307,21 @@ def post(self, request, slug, project_id):
         ):
             serializer = CycleCreateSerializer(data=request.data, context={"request": request})
             if serializer.is_valid():
-                if (
-                    request.data.get("external_id")
-                    and request.data.get("external_source")
-                    and Cycle.objects.filter(
-                        project_id=project_id,
-                        workspace__slug=slug,
-                        external_source=request.data.get("external_source"),
-                        external_id=request.data.get("external_id"),
-                    ).exists()
-                ):
+                if request.data.get("external_id") and request.data.get("external_source"):
                     cycle = Cycle.objects.filter(
                         workspace__slug=slug,
                         project_id=project_id,
                         external_source=request.data.get("external_source"),
                         external_id=request.data.get("external_id"),
                     ).first()
-                    return Response(
-                        {
-                            "error": "Cycle with the same external id and external source already exists",
-                            "id": str(cycle.id),
-                        },
-                        status=status.HTTP_409_CONFLICT,
-                    )
+                    if cycle:
+                        return Response(
+                            {
+                                "error": "Cycle with the same external id and external source already exists",
+                                "id": str(cycle.id),
+                            },
+                            status=status.HTTP_409_CONFLICT,
+                        )
                 serializer.save(project_id=project_id)
                 # Send the model activity
                 model_activity.delay(