#4843: Use subqueries when counting multiple types of related objects

netbox/virtualization/tables.py

@@ -34,6 +34,14 @@ VIRTUALMACHINE_PRIMARY_IP = """
 {{ record.primary_ip4.address.ip|default:"" }}
 """
 
+CLUSTER_DEVICE_COUNT = """
+<a href="{% url 'dcim:device_list' %}?cluster_id={{ record.pk }}">{{ value|default:0 }}</a>
+"""
+
+CLUSTER_VM_COUNT = """
+<a href="{% url 'virtualization:virtualmachine_list' %}?cluster_id={{ record.pk }}">{{ value|default:0 }}</a>
+"""
+
 
 #
 # Cluster types
@@ -94,14 +102,12 @@ class ClusterTable(BaseTable):
         viewname='dcim:site',
         args=[Accessor('site.slug')]
     )
-    device_count = tables.Column(
-        accessor=Accessor('devices.count'),
-        orderable=False,
+    device_count = tables.TemplateColumn(
+        template_code=CLUSTER_DEVICE_COUNT,
         verbose_name='Devices'
     )
-    vm_count = tables.Column(
-        accessor=Accessor('virtual_machines.count'),
-        orderable=False,
+    vm_count = tables.TemplateColumn(
+        template_code=CLUSTER_VM_COUNT,
         verbose_name='VMs'
     )
     tags = TagColumn(

netbox/virtualization/views.py

@@ -10,6 +10,7 @@ from dcim.models import Device, Interface
 from dcim.tables import DeviceTable
 from extras.views import ObjectConfigContextView
 from ipam.models import Service
+from utilities.utils import get_subquery
 from utilities.views import (
     BulkComponentCreateView, BulkDeleteView, BulkEditView, BulkImportView, ComponentCreateView, ObjectDeleteView,
     ObjectEditView, ObjectListView,
@@ -94,7 +95,10 @@ class ClusterGroupBulkDeleteView(PermissionRequiredMixin, BulkDeleteView):
 
 class ClusterListView(PermissionRequiredMixin, ObjectListView):
     permission_required = 'virtualization.view_cluster'
-    queryset = Cluster.objects.prefetch_related('type', 'group', 'site', 'tenant')
+    queryset = Cluster.objects.prefetch_related('type', 'group', 'site', 'tenant').annotate(
+        device_count=get_subquery(Device, 'cluster'),
+        vm_count=get_subquery(VirtualMachine, 'cluster')
+    )
     table = tables.ClusterTable
     filterset = filters.ClusterFilterSet
     filterset_form = forms.ClusterFilterForm