fix: resolved pos return setting to default mode of payment instead of user selection (backport #45377) (#45419)

fix: resolved pos return setting to default mode of payment instead of user selection (#45377)

* fix: resolved pos return setting to default mode of payment instead of user selection

* refactor: removed console log statement

* refactor: moved get_payment_data to sales_and_purchase_return.py

(cherry picked from commit 54d234e05d)

Co-authored-by: Diptanil Saha <diptanil@frappe.io>

erpnext/controllers/sales_and_purchase_return.py

@@ -1150,3 +1150,9 @@ def get_available_serial_nos(serial_nos, warehouse):
 	return frappe.get_all(
 		"Serial No", filters={"warehouse": warehouse, "name": ("in", serial_nos)}, pluck="name"
 	)
+
+
+@frappe.whitelist()
+def get_payment_data(invoice):
+	payment = frappe.db.get_all("Sales Invoice Payment", {"parent": invoice}, ["mode_of_payment", "amount"])
+	return payment

erpnext/public/js/controllers/taxes_and_totals.js

@@ -822,7 +822,7 @@ erpnext.taxes_and_totals = class TaxesAndTotals extends erpnext.payments {
 		}
 	}
 
-	set_total_amount_to_default_mop() {
+	async set_total_amount_to_default_mop() {
 		let grand_total = this.frm.doc.rounded_total || this.frm.doc.grand_total;
 		let base_grand_total = this.frm.doc.base_rounded_total || this.frm.doc.base_grand_total;
 
@@ -844,6 +844,45 @@ erpnext.taxes_and_totals = class TaxesAndTotals extends erpnext.payments {
 			);
 		}
 
+		/*
+		During returns, if an user select mode of payment other than
+		default mode of payment, it should retain the user selection
+		instead resetting it to default mode of payment.
+		*/
+
+		let payment_amount = 0;
+		this.frm.doc.payments.forEach(payment => {
+			payment_amount += payment.amount
+		});
+
+		if (payment_amount == total_amount_to_pay) {
+			return;
+		}
+
+		/*
+		For partial return, if the payment was made using single mode of payment
+		it should set the return to that mode of payment only.
+		*/
+
+		let return_against_mop = await frappe.call({
+			method: 'erpnext.controllers.sales_and_purchase_return.get_payment_data',
+			args: {
+				invoice: this.frm.doc.return_against
+			}
+		});
+
+		if (return_against_mop.message.length === 1) {
+			this.frm.doc.payments.forEach(payment => {
+				if (payment.mode_of_payment == return_against_mop.message[0].mode_of_payment) {
+					payment.amount = total_amount_to_pay;
+				} else {
+					payment.amount = 0;
+				}
+			});
+			this.frm.refresh_fields();
+			return;
+		}
+
 		this.frm.doc.payments.find(payment => {
 			if (payment.default) {
 				payment.amount = total_amount_to_pay;