Optimize admin queries

Contributed by https://github.com/henribru in #110

Co-authored-by: henribru <6639509+henribru@users.noreply.github.com>

README.md

@@ -196,6 +196,7 @@ You must change your Django settings and replace the app name:
 
 * [dev](https://github.com/boxine/django-huey-monitor/compare/v0.5.0...master)
   * Test against Django v3.2, v4.0 and Python v3.8 - v3.10
+  * Optimize Admin change list ([contributed by henribru](https://github.com/boxine/django-huey-monitor/pull/110))
   * _tbc_
 * [v0.5.0 - 10.02.2022](https://github.com/boxine/django-huey-monitor/compare/v0.4.6...v0.5.0)
   * Refactor models: Remove `TaskProgressModel` and store progress information into `TaskModel`

huey_monitor/admin.py

@@ -1,12 +1,14 @@
 from bx_django_utils.templatetags.humanize_time import human_duration
 from django.contrib import admin, messages
 from django.contrib.admin.views.main import ChangeList
+from django.db.models import OuterRef, Prefetch
 from django.shortcuts import redirect
 from django.template.loader import render_to_string
 from django.urls import path, reverse
 from django.utils import timezone
 from django.utils.translation import gettext_lazy as _
 from huey.contrib.djhuey import HUEY
+from huey.signals import SIGNAL_EXECUTING
 
 from huey_monitor.models import SignalInfoModel, TaskModel
 
@@ -17,7 +19,21 @@ def get_queryset(self, request):
         List only the main-tasks (sub-tasks will be inlined)
         """
         qs = super().get_queryset(request)
-        qs = qs.filter(parent_task__isnull=True)
+        executing_dt = SignalInfoModel.objects.filter(
+            task_id=OuterRef("task_id"), signal_name=SIGNAL_EXECUTING
+        ).values('create_dt')[:1]
+        qs = (
+            qs.filter(parent_task__isnull=True)
+            .prefetch_related(
+                Prefetch(
+                    "sub_tasks",
+                    queryset=TaskModel.objects.select_related("state")
+                    .annotate(executing_dt=executing_dt)
+                    .order_by('-create_dt'),
+                )
+            )
+            .annotate(executing_dt=executing_dt)
+        )
         return qs
 
 
@@ -27,10 +43,10 @@ def get_changelist(self, request, **kwargs):
         return TaskModelChangeList
 
     def column_name(self, obj):
-        qs = TaskModel.objects.filter(parent_task_id=obj.pk).order_by('-create_dt')
+        qs = obj.sub_tasks.all()
         context = {
             'main_task': obj,
-            'sub_tasks': qs
+            'sub_tasks': qs,
         }
         return render_to_string(
             template_name='admin/huey_monitor/taskmodel/column_name.html',
@@ -175,3 +191,6 @@ def task_name(self, obj):
 
     def has_change_permission(self, request, obj=None):
         return False
+
+    def get_queryset(self, request):
+        return super().get_queryset(request).prefetch_related("task")

huey_monitor/migrations/0010_alter_taskmodel_parent_task.py

@@ -0,0 +1,27 @@
+# Generated by Django 3.2.14 on 2022-11-25 12:11
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('huey_monitor', '0009_fix_optinal_fields'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='taskmodel',
+            name='parent_task',
+            field=models.ForeignKey(
+                blank=True,
+                editable=False,
+                help_text='Only set if this task is a sub task started from his parent.',
+                null=True,
+                on_delete=django.db.models.deletion.CASCADE,
+                related_name='sub_tasks',
+                to='huey_monitor.taskmodel',
+                verbose_name='Parent Task',
+            ),
+        ),
+    ]

huey_monitor/models.py

@@ -43,7 +43,7 @@ class TaskModel(TimetrackingBaseModel):
         to='self',
         null=True, blank=True,
         editable=False,
-        related_name='+',
+        related_name='sub_tasks',
         on_delete=models.CASCADE,
         verbose_name=_('Parent Task'),
         help_text=_('Only set if this task is a sub task started from his parent.'),