Change purchased_from options so supplier deletion does not delete assets

assets/migrations/0023_alter_asset_purchased_from.py

@@ -0,0 +1,19 @@
+# Generated by Django 3.2.12 on 2022-02-14 15:13
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('assets', '0022_alter_cabletype_unique_together'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='asset',
+            name='purchased_from',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='assets', to='assets.supplier'),
+        ),
+    ]

assets/models.py

@@ -128,7 +128,7 @@ class Asset(models.Model, RevisionMixin):
     category = models.ForeignKey(to=AssetCategory, on_delete=models.CASCADE)
     status = models.ForeignKey(to=AssetStatus, on_delete=models.CASCADE)
     serial_number = models.CharField(max_length=150, blank=True)
-    purchased_from = models.ForeignKey(to=Supplier, on_delete=models.CASCADE, blank=True, null=True, related_name="assets")
+    purchased_from = models.ForeignKey(to=Supplier, on_delete=models.SET_NULL, blank=True, null=True, related_name="assets")
     date_acquired = models.DateField()
     date_sold = models.DateField(blank=True, null=True)
     purchase_price = models.DecimalField(blank=True, null=True, decimal_places=2, max_digits=10)