fix: calc platform asset count

apps/assets/api/platform.py

@@ -1,10 +1,10 @@
-from django.db.models import Count
+from django.db.models import Subquery, OuterRef, Count, Value
+from django.db.models.functions import Coalesce
 from django_filters import rest_framework as filters
 from rest_framework import generics
 from rest_framework import serializers
 from rest_framework.decorators import action
 from rest_framework.response import Response
-
 from assets.const import AllTypes
 from assets.models import Platform, Node, Asset, PlatformProtocol
 from assets.serializers import PlatformSerializer, PlatformProtocolSerializer, PlatformListSerializer
@@ -42,7 +42,10 @@ class AssetPlatformViewSet(JMSModelViewSet):
 
     def get_queryset(self):
         # 因为没有走分页逻辑，所以需要这里 prefetch
-        queryset = super().get_queryset().annotate(assets_amount=Count('assets')).prefetch_related(
+        asset_count_subquery = Asset.objects.filter(platform=OuterRef('pk')).values('platform').annotate(
+            count=Count('id')).values('count')
+        queryset = super().get_queryset().annotate(
+            assets_amount=Coalesce(Subquery(asset_count_subquery), Value(0))).prefetch_related(
             'protocols', 'automation', 'labels', 'labels__label'
         )
         queryset = queryset.filter(type__in=AllTypes.get_types_values())