feat(models): add validity constraint on certificate model

logbook/migrations/0015_certificate_validity_after_issue.py

@@ -0,0 +1,23 @@
+# Generated by Django 4.2.6 on 2023-10-30 19:32
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("logbook", "0014_certificate_relinquished"),
+    ]
+
+    operations = [
+        migrations.AddConstraint(
+            model_name="certificate",
+            constraint=models.CheckConstraint(
+                check=models.Q(
+                    ("valid_until__isnull", True),
+                    ("valid_until__gt", models.F("issue_date")),
+                    _connector="OR",
+                ),
+                name="validity_after_issue",
+            ),
+        ),
+    ]

logbook/models.py

@@ -151,6 +151,12 @@ class Certificate(models.Model):
     relinquished = models.BooleanField(default=False)
 
     class Meta:
+        constraints = (
+            CheckConstraint(
+                check=Q(valid_until__isnull=True) | Q(valid_until__gt=F("issue_date")),
+                name="validity_after_issue",
+            ),
+        )
         ordering = ("name", "-valid_until")
 
     def __str__(self):