Add constraint that training items must have unique reference numbers

training/migrations/0009_auto_20211221_1539.py

@@ -0,0 +1,22 @@
+# Generated by Django 3.1.13 on 2021-12-21 15:39
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('training', '0008_trainingitem_active'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='trainingcategory',
+            name='reference_number',
+            field=models.CharField(max_length=3, unique=True),
+        ),
+        migrations.AlterUniqueTogether(
+            name='trainingitem',
+            unique_together={('reference_number', 'active', 'category')},
+        ),
+    ]