Hi,

To Add additional validation in the `set_discount` function in Odoo 17 POS, when using `var maxDiscount = this.product.maxDiscount`, it is essential to import the required classes and an Error Popup to facilitate proper validation. Following this, you can modify the code as outlined below:

import { Orderline } from "@point_of_sale/app/store/models";
import { patch } from "@web/core/utils/patch";import { ErrorPopup } from "@point_of_sale/app/errors/popups/error_popup";

patch(Orderline.prototype, {
    async set_discount(discount) {
        var parsed_discount =
            typeof discount === "number" ?
            discount :
            isNaN(parseFloat(discount)) ?
            0 :
            oParseFloat("" + discount);

        var disc = Math.min(Math.max(parsed_discount || 0, 0), 100);
        var maxDiscount = this.product.maxDiscount;
        if (disc > maxDiscount) {
            await this.env.services.popup.add(ErrorPopup, {
                title: _t("Exceed Discount Limit!"),
                body: _t("Sorry, Discount is not allowed. Maximum discount for this Product is %s %", maxDiscount),
            });
            this.discount = 0;
            this.discountStr = "0";
        } else {
            this.discount = disc;
            this.discountStr = "" + disc;
        }
    }

Regards