From b2a80c355634ec4e99a73def97d1c6e64b7ae700 Mon Sep 17 00:00:00 2001
From: Zeno Dalla Valle <zenodallavalle@gmail.com>
Date: Tue, 9 Dec 2025 12:30:59 +0100
Subject: [PATCH] Add unique constraints to ClockedSchedule and CrontabSchedule
 models

---
 ...r_clockedschedule_clocked_time_and_more.py | 41 +++++++++++++++++++
 django_celery_beat/models.py                  | 21 +++++++++-
 2 files changed, 60 insertions(+), 2 deletions(-)
 create mode 100644 django_celery_beat/migrations/0020_alter_clockedschedule_clocked_time_and_more.py

diff --git a/django_celery_beat/migrations/0020_alter_clockedschedule_clocked_time_and_more.py b/django_celery_beat/migrations/0020_alter_clockedschedule_clocked_time_and_more.py
new file mode 100644
index 00000000..040922fa
--- /dev/null
+++ b/django_celery_beat/migrations/0020_alter_clockedschedule_clocked_time_and_more.py
@@ -0,0 +1,41 @@
+# Generated by Django 5.2.9 on 2025-12-09 09:48
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("django_celery_beat", "0019_alter_periodictasks_options"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="clockedschedule",
+            name="clocked_time",
+            field=models.DateTimeField(
+                help_text="Run the task at clocked time",
+                unique=True,
+                verbose_name="Clock Time",
+            ),
+        ),
+        migrations.AddConstraint(
+            model_name="crontabschedule",
+            constraint=models.UniqueConstraint(
+                fields=(
+                    "minute",
+                    "hour",
+                    "day_of_month",
+                    "month_of_year",
+                    "day_of_week",
+                    "timezone",
+                ),
+                name="unique_crontab",
+            ),
+        ),
+        migrations.AddConstraint(
+            model_name="intervalschedule",
+            constraint=models.UniqueConstraint(
+                fields=("every", "period"), name="unique_interval"
+            ),
+        ),
+    ]
diff --git a/django_celery_beat/models.py b/django_celery_beat/models.py
index ad53a288..b92f05c4 100644
--- a/django_celery_beat/models.py
+++ b/django_celery_beat/models.py
@@ -173,6 +173,9 @@ class Meta:
         verbose_name = _('interval')
         verbose_name_plural = _('intervals')
         ordering = ['period', 'every']
+        constraints = [
+            models.UniqueConstraint(fields=["every", "period"], name="unique_interval")
+        ]
 
     @property
     def schedule(self):
@@ -214,8 +217,9 @@ class ClockedSchedule(models.Model):
     """clocked schedule."""
 
     clocked_time = models.DateTimeField(
-        verbose_name=_('Clock Time'),
-        help_text=_('Run the task at clocked time'),
+        verbose_name=_("Clock Time"),
+        help_text=_("Run the task at clocked time"),
+        unique=True,
     )
 
     class Meta:
@@ -314,6 +318,19 @@ class Meta:
         verbose_name_plural = _('crontabs')
         ordering = ['month_of_year', 'day_of_month',
                     'day_of_week', 'hour', 'minute', 'timezone']
+        constraints = [
+            models.UniqueConstraint(
+                fields=[
+                    "minute",
+                    "hour",
+                    "day_of_month",
+                    "month_of_year",
+                    "day_of_week",
+                    "timezone",
+                ],
+                name="unique_crontab",
+            )
+        ]
 
     @property
     def human_readable(self):