feat: add discount_amount to payment_order and receipt_order, and change total_amount logic

business/migrations/0016_payment_receipt_discount.py

@@ -0,0 +1,35 @@
+from decimal import Decimal
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('business', '0015_payment_receipt_bank_and_markup'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='paymentorder',
+            name='discount_amount',
+            field=models.DecimalField(
+                decimal_places=2,
+                default=Decimal('0'),
+                max_digits=15,
+                verbose_name='折扣金额',
+            ),
+        ),
+        migrations.AddField(
+            model_name='receiptorder',
+            name='discount_amount',
+            field=models.DecimalField(
+                decimal_places=2,
+                default=Decimal('0'),
+                max_digits=15,
+                verbose_name='折扣金额',
+            ),
+        ),
+    ]
+
+