Hi,

 I want to add some features to POS but I'm not familiar to js. 

So for PaymentScreenWidget I was able to add some new functions and to change others, like this :

function openerp_vi_pos_print_invoice(instance, module){
    var QWeb = instance.web.qweb;
	var _t = instance.web._t;
	console.log('print_');
    console.log(module);
	module.PaymentScreenWidget.include({
        init: function(parent, options) {
            var self = this;
            this._super(parent,options);
			//console.log('Init!!!!');
        },
        show: function(){
            this._super();
            var self = this;
            this.add_action_button({
                    label: _t('Print Inv.'),
					name: 'b_invoice',
                    icon: '/vi_pos/static/src/img/icons/print.png',
                    click: function(){  
                        self.print_invoice_func({invoice_vi: true, invoice:true});
                    },
                });
			this.update_payment_summary();
        },
        print_invoice_func: function(options) {
			var self = this;
            options = options || {};
			var currentOrder = this.pos.get('selectedOrder');
			//console.log(options.invoice_vi && options.invoice);
			if (options.invoice_vi && options.invoice) {
				self.validate_order({invoice: options.invoice, invoice_vi:options.invoice_vi});
			}
        },
		update_payment_summary: function() {
			this._super();
            if(this.pos_widget.action_bar){
                this.pos_widget.action_bar.set_button_disabled('b_invoice', !this.is_paid());
            }
},
 });
}

But when I tried to the same to PosModel:

function openerp_vi_pos_models(instance, module){ //module is instance.point_of_sale
    var QWeb = instance.web.qweb;
	var _t = instance.web._t;
	module.PosModel.include({
      
        new_func: function(order){
            var self = this;
            var invoiced = new $.Deferred(); 
            if(!order.get_client()){
                invoiced.reject('error-no-client');
                return invoiced;
            }
            var order_id = this.db.add_order(order.export_as_JSON());
            ....
             ....
        },
    });
}

I get an error Uncaught TypeError: module.PosModel.include is not a function

So I print the variable module through console.log(module); and I notice that "PaymentScreenWidget" it has defined the include function and the "prototype" is Class and in PosModel we don't have the function include and the prototype is Surrogate.

If I don't have the include function how do I add a function to PosModel?

Thanks