fix: Sales Return cancellation if linked with Payment Entry (#26551)

erpnext/accounts/doctype/purchase_invoice/purchase_invoice.py

@@ -22,7 +22,7 @@ from erpnext.assets.doctype.asset.asset import get_asset_account, is_cwip_accoun
 from frappe.model.mapper import get_mapped_doc
 from six import iteritems
 from erpnext.accounts.doctype.sales_invoice.sales_invoice import validate_inter_company_party, update_linked_doc,\
-	unlink_inter_company_doc
+	unlink_inter_company_doc, check_if_return_invoice_linked_with_payment_entry
 from erpnext.accounts.doctype.tax_withholding_category.tax_withholding_category import get_party_tax_withholding_details
 from erpnext.accounts.deferred_revenue import validate_service_stop_date
 from erpnext.stock.doctype.purchase_receipt.purchase_receipt import get_item_account_wise_additional_cost
@@ -1014,6 +1014,8 @@ class PurchaseInvoice(BuyingController):
 				}, item=self))
 
 	def on_cancel(self):
+		check_if_return_invoice_linked_with_payment_entry(self)
+
 		super(PurchaseInvoice, self).on_cancel()
 
 		self.check_on_hold_or_closed_status()

erpnext/accounts/doctype/sales_invoice/sales_invoice.py

@@ -290,6 +290,8 @@ class SalesInvoice(SellingController):
 		self.update_time_sheet(None)
 
 	def on_cancel(self):
+		check_if_return_invoice_linked_with_payment_entry(self)
+
 		super(SalesInvoice, self).on_cancel()
 
 		self.check_sales_order_on_hold_or_close("sales_order")
@@ -1941,3 +1943,41 @@ def create_dunning(source_name, target_doc=None):
 		}
 	}, target_doc, set_missing_values)
 	return doclist
+
+def check_if_return_invoice_linked_with_payment_entry(self):
+	# If a Return invoice is linked with payment entry along with other invoices,
+	# the cancellation of the Return causes allocated amount to be greater than paid
+
+	if not frappe.db.get_single_value('Accounts Settings', 'unlink_payment_on_cancellation_of_invoice'):
+		return
+
+	payment_entries = []
+	if self.is_return and self.return_against:
+		invoice = self.return_against
+	else:
+		invoice = self.name
+
+	payment_entries = frappe.db.sql_list("""
+		SELECT
+			t1.name
+		FROM
+			`tabPayment Entry` t1, `tabPayment Entry Reference` t2
+		WHERE
+			t1.name = t2.parent
+			and t1.docstatus = 1
+			and t2.reference_name = %s
+			and t2.allocated_amount < 0
+		""", invoice)
+
+	links_to_pe = []
+	if payment_entries:
+		for payment in payment_entries:
+			payment_entry = frappe.get_doc("Payment Entry", payment)
+			if len(payment_entry.references) > 1:
+				links_to_pe.append(payment_entry.name)
+		if links_to_pe:
+			payment_entries_link = [get_link_to_form('Payment Entry', name, label=name) for name in links_to_pe]
+			message = _("Please cancel and amend the Payment Entry")
+			message += " " + ", ".join(payment_entries_link) + " "
+			message += _("to unallocate the amount of this Return Invoice before cancelling it.")
+			frappe.throw(message)