fix(selling): reset stale item details on item change

(cherry picked from commit 009961edc7)

erpnext/controllers/tests/test_reactivity.py

@@ -46,3 +46,39 @@ class TestReactivity(ERPNextTestSuite):
 			with self.subTest(field=field):
 				self.assertIsNotNone(itm.get(field[0]))
 		si.save().submit()
+
+	def test_item_change_clears_stale_item_details(self):
+		from erpnext.selling.doctype.sales_order.test_sales_order import make_sales_order
+		from erpnext.stock.doctype.item.test_item import make_item
+
+		old_item = make_item(properties={"is_stock_item": 0, "stock_uom": "Nos"})
+		new_item = make_item(
+			properties={
+				"is_stock_item": 0,
+				"stock_uom": "Kg",
+				"weight_per_unit": 2,
+				"weight_uom": "Kg",
+			}
+		)
+		sales_order = make_sales_order(item_code=old_item.name, do_not_submit=True)
+
+		item = sales_order.items[0]
+		self.assertEqual(item.uom, "Nos")
+		row_state = (item.qty, item.warehouse, item.delivery_date)
+
+		sales_order.ignore_pricing_rule = 1
+		item.weight_per_unit = 10
+		item.weight_uom = "Nos"
+		item.barcode = "OLD-BARCODE"
+		item.pricing_rules = "OLD-PRICING-RULE"
+		item.item_code = new_item.name
+		sales_order.process_item_selection(item.idx)
+
+		self.assertEqual(item.uom, "Kg")
+		self.assertEqual(item.stock_uom, "Kg")
+		self.assertEqual(item.conversion_factor, 1)
+		self.assertEqual(item.weight_per_unit, 2)
+		self.assertEqual(item.weight_uom, "Kg")
+		self.assertIsNone(item.barcode)
+		self.assertFalse(item.pricing_rules)
+		self.assertEqual((item.qty, item.warehouse, item.delivery_date), row_state)

erpnext/utilities/transaction_base.py

@@ -357,6 +357,17 @@ class TransactionBase(StatusUpdater):
 		if not item_obj.item_code:
 			return
 
+		# Do not carry item-specific values from the previously selected item.
+		for fieldname in (
+			"weight_per_unit",
+			"weight_uom",
+			"uom",
+			"conversion_factor",
+			"barcode",
+			"pricing_rules",
+		):
+			item_obj.set(fieldname, None)
+
 		# 'item_details' has latest item related values
 		item_details = self.fetch_item_details(item_obj)