Update migration for generic relation

courses/models.py

@@ -24,6 +24,7 @@ from .notes.models import Note
 from .course_material.models import CourseMaterial
 from .classes.models import Class
 from .classroom.models import Classroom, Event
+from .scheduling.models import ScheduledTask
 
 import re
 
@@ -948,6 +949,7 @@ class Lesson(PositionedModel):
         blank=True,
         default=None,
     )
+    scheduled_task = GenericRelation(ScheduledTask, related_query_name='lesson')
 
     collection_name = 'course'
     class Meta:
@@ -1047,6 +1049,7 @@ class Unit(PositionedModel):
         blank=True,
         default=None,
     )
+    scheduled_task = GenericRelation(ScheduledTask, related_query_name='unit')
 
     collection_name = 'lesson'
 

courses/scheduling/migrations/0001_initial.py

-# Generated by Django 2.2.24 on 2021-12-07 12:11
+# Generated by Django 2.2.24 on 2021-12-07 13:32
 
 from django.db import migrations, models
+import django.db.models.deletion
 
 
 class Migration(migrations.Migration):
@@ -8,6 +9,7 @@ class Migration(migrations.Migration):
     initial = True
 
     dependencies = [
+        ('contenttypes', '0002_remove_content_type_name'),
     ]
 
     operations = [
@@ -16,9 +18,11 @@ class Migration(migrations.Migration):
             fields=[
                 ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                 ('task_hash', models.CharField(blank=True, max_length=255, verbose_name='Name')),
+                ('object_id', models.PositiveIntegerField()),
                 ('release_date', models.DateTimeField(blank=True, default=None, null=True, verbose_name='Date')),
                 ('created_at', models.DateTimeField(auto_now_add=True)),
                 ('updated_at', models.DateTimeField(auto_now=True)),
+                ('content_type', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='contenttypes.ContentType')),
             ],
             options={
                 'verbose_name': 'ScheduledTask',

courses/scheduling/models.py

 from django.db import models
 from django.conf import settings
 from django.urls import reverse_lazy
-
-from courses.models import Lesson, Unit
 from django.utils.translation import ugettext_lazy as _
-from django.contrib.contenttypes.fields import GenericRelation
+from django.contrib.contenttypes.fields import GenericForeignKey
+from django.contrib.contenttypes.models import ContentType
 
 
 class ScheduledTask(models.Model):
@@ -18,9 +17,15 @@ class ScheduledTask(models.Model):
         max_length=255,
         blank=True,
     )
-
-    related_obj = GenericRelation(Lesson, Unit,)
-
+    content_type = models.ForeignKey(
+        ContentType,
+        models.CASCADE,
+    )
+    object_id = models.PositiveIntegerField()
+    content_object = GenericForeignKey(
+        'content_type',
+        'object_id',
+    )
     release_date = models.DateTimeField(
         _('Date'),
         null=True,

courses/signals.py

 from django.db.models.signals import pre_save
 from django.dispatch import receiver
+from django.contrib.contenttypes.models import ContentType
 
 from .models import Lesson, Unit
+from .scheduling.models import ScheduledTask
 from .tasks import publish_lesson, publish_unit
 
+from celery.result import AsyncResult
+
 
 @receiver(pre_save, sender=Lesson)
 def lesson_created_or_updated(sender, instance: Lesson, **kwargs):
@@ -11,7 +15,25 @@ def lesson_created_or_updated(sender, instance: Lesson, **kwargs):
         previous_lesson = Lesson.objects.get(id=instance.id)
 
     if (not instance.id or instance.release_date != previous_lesson.release_date) and instance.release_date:
-        publish_lesson.apply_async(args=[instance.id], eta=instance.release_date)
+        previous_task_hask = ''
+        ct = ContentType.objects.get_for_model(comment)
+
+        st = ScheduledTask.objects.filter(Content_type=ct, object_id=instance.id)
+        if st.exists():
+            previous_task_hask = st.task_hash
+        else:
+            st = ScheduledTask.objects.create(content_object=instance)
+
+        if previous_task_hask:
+            res = AsyncResult(previous_task_hask)
+            res.revoke()
+
+        new_task_hash = publish_lesson.apply_async(args=[instance.id], eta=instance.release_date)
+        st.task_hash = task_hash
+        st.content_object = instance
+        st.release_date = instance.release_date
+        st.save()
+
 
 @receiver(pre_save, sender=Unit)
 def unit_created_or_updated(sender, instance: Unit, **kwargs):