Merge pull request #1232 from syucream/feature/store-prefetched-entries

Store prefetched entries in context to avoid N+1 on JobListAPI

Author: hinashi

job/api_v2/serializers.py

@@ -28,6 +28,8 @@ class JobSerializers(serializers.ModelSerializer):
     target = serializers.SerializerMethodField(method_name="get_target")
     passed_time = serializers.SerializerMethodField(method_name="get_passed_time")
 
+    PREFETCHED_ENTRIES_KEY = "__prefetched_entries"
+
     class Meta:
         model = Job
         fields = ["id", "text", "status", "operation", "created_at", "target", "passed_time"]
@@ -36,12 +38,19 @@ class Meta:
     def get_target(self, obj: Job) -> JobTarget | None:
         if obj.target is not None:
             if obj.target.objtype == ACLObjType.Entry:
-                sub = Entry.objects.filter(id=obj.target.id).select_related("schema").first()
+                sub: dict = self.context.get(self.PREFETCHED_ENTRIES_KEY, {}).get(obj.target.id)
+                if not sub:
+                    sub = (
+                        Entry.objects.filter(id=obj.target.id)
+                        .select_related("schema")
+                        .values("id", "name", "schema__id", "schema__name")
+                        .first()
+                    )
                 return {
-                    "id": sub.id,
-                    "name": sub.name,
-                    "schema_id": sub.schema.id,
-                    "schema_name": sub.schema.name,
+                    "id": sub["id"],
+                    "name": sub["name"],
+                    "schema_id": sub["schema__id"],
+                    "schema_name": sub["schema__name"],
                 }
             else:
                 return {

job/api_v2/views.py

@@ -9,8 +9,10 @@
 from rest_framework.request import Request
 from rest_framework.response import Response
 
+from airone.lib.acl import ACLObjType
 from airone.lib.drf import FileIsNotExistsError, InvalidValueError, JobIsNotDoneError
 from airone.lib.http import get_download_response
+from entry.models import Entry
 from job.api_v2.serializers import JobSerializers
 from job.models import Job, JobOperation, JobStatus
 
@@ -110,6 +112,21 @@ def get_queryset(self) -> QuerySet:
 
         return Job.objects.filter(query).select_related("target").order_by("-created_at")
 
+    def get_serializer_context(self):
+        context = super().get_serializer_context()
+
+        # prefetch target entries, then pass it via context manually to avoid N+1 in serializer
+        qs = self.paginate_queryset(self.get_queryset().values("target__id", "target__objtype"))
+        target_ids = [int(r["target__id"]) for r in qs if r["target__objtype"] == ACLObjType.Entry]
+        entries = (
+            Entry.objects.filter(id__in=target_ids)
+            .select_related("schema")
+            .values("id", "name", "schema__id", "schema__name")
+        )
+        context[JobSerializers.PREFETCHED_ENTRIES_KEY] = {e["id"]: e for e in entries}
+
+        return context
+
 
 class JobRerunAPI(generics.UpdateAPIView):
     serializer_class = serializers.Serializer