fix: Fetch and set Item Tax Template via Update Items

erpnext/buying/doctype/purchase_order/test_purchase_order.py

@@ -202,6 +202,53 @@ class TestPurchaseOrder(unittest.TestCase):
 		self.assertRaises(frappe.ValidationError, update_child_qty_rate,'Purchase Order', trans_item, po.name)
 		frappe.set_user("Administrator")
 
+	def test_update_child_with_tax_template(self):
+		tax_template = "_Test Account Excise Duty @ 10"
+		item =  "_Test Item Home Desktop 100"
+
+		if not frappe.db.exists("Item Tax", {"parent":item, "item_tax_template":tax_template}):
+			item_doc = frappe.get_doc("Item", item)
+			item_doc.append("taxes", {
+				"item_tax_template": tax_template,
+				"valid_from": nowdate()
+			})
+			item_doc.save()
+		else:
+			# update valid from
+			frappe.db.sql("""UPDATE `tabItem Tax` set valid_from = CURDATE()
+				where parent = %(item)s and item_tax_template = %(tax)s""",
+					{"item": item, "tax": tax_template})
+
+		po = create_purchase_order(item_code=item, qty=1, do_not_save=1)
+
+		po.append("taxes", {
+			"account_head": "_Test Account Excise Duty - _TC",
+			"charge_type": "On Net Total",
+			"cost_center": "_Test Cost Center - _TC",
+			"description": "Excise Duty",
+			"doctype": "Purchase Taxes and Charges",
+			"rate": 10
+		})
+		po.insert()
+		po.submit()
+
+		self.assertEqual(po.taxes[0].tax_amount, 50)
+		self.assertEqual(po.taxes[0].total, 550)
+
+		items = json.dumps([
+			{'item_code' : item, 'rate' : 500, 'qty' : 1, 'docname': po.items[0].name},
+			{'item_code' : item, 'rate' : 100, 'qty' : 1} # added item
+		])
+		update_child_qty_rate('Purchase Order', items, po.name)
+
+		po.reload()
+		self.assertEqual(po.taxes[0].tax_amount, 60)
+		self.assertEqual(po.taxes[0].total, 660)
+
+		frappe.db.sql("""UPDATE `tabItem Tax` set valid_from = NULL
+				where parent = %(item)s and item_tax_template = %(tax)s""",
+					{"item": item, "tax": tax_template})
+
 	def test_update_qty(self):
 		po = create_purchase_order()
 

erpnext/controllers/accounts_controller.py

@@ -20,7 +20,7 @@ from erpnext.accounts.doctype.pricing_rule.utils import (apply_pricing_rule_on_t
 from erpnext.exceptions import InvalidCurrency
 from six import text_type
 from erpnext.accounts.doctype.accounting_dimension.accounting_dimension import get_accounting_dimensions
-from erpnext.stock.get_item_details import get_item_warehouse
+from erpnext.stock.get_item_details import get_item_warehouse, _get_item_tax_template, get_item_tax_map
 from erpnext.stock.doctype.packed_item.packed_item import make_packing_list
 
 force_item_fields = ("item_group", "brand", "stock_uom", "is_fixed_asset", "item_tax_rate", "pricing_rules")
@@ -1127,6 +1127,18 @@ def get_supplier_block_status(party_name):
 	}
 	return info
 
+def set_child_tax_template_and_map(item, child_item, parent_doc):
+	args = {
+			'item_code': item.item_code,
+			'posting_date': parent_doc.transaction_date,
+			'tax_category': parent_doc.get('tax_category'),
+			'company': parent_doc.get('company')
+		}
+
+	child_item.item_tax_template = _get_item_tax_template(args, item.taxes)
+	if child_item.get("item_tax_template"):
+		child_item.item_tax_rate = get_item_tax_map(parent_doc.get('company'), child_item.item_tax_template, as_json=True)
+
 def set_sales_order_defaults(parent_doctype, parent_doctype_name, child_docname, trans_item):
 	"""
 	Returns a Sales Order Item child item containing the default values
@@ -1140,6 +1152,7 @@ def set_sales_order_defaults(parent_doctype, parent_doctype_name, child_docname,
 	child_item.delivery_date = trans_item.get('delivery_date') or p_doc.delivery_date
 	child_item.conversion_factor = flt(trans_item.get('conversion_factor')) or get_conversion_factor(item.item_code, item.stock_uom).get("conversion_factor") or 1.0
 	child_item.uom = item.stock_uom
+	set_child_tax_template_and_map(item, child_item, p_doc)
 	child_item.warehouse = get_item_warehouse(item, p_doc, overwrite_warehouse=True)
 	if not child_item.warehouse:
 		frappe.throw(_("Cannot find {} for item {}. Please set the same in Item Master or Stock Settings.")
@@ -1162,6 +1175,7 @@ def set_purchase_order_defaults(parent_doctype, parent_doctype_name, child_docna
 	child_item.uom = item.stock_uom
 	child_item.base_rate = 1 # Initiallize value will update in parent validation
 	child_item.base_amount = 1 # Initiallize value will update in parent validation
+	set_child_tax_template_and_map(item, child_item, p_doc)
 	return child_item
 
 def validate_and_delete_children(parent, data):