Update shopping cart when change spinner value - ajax

Question

I have a shopping cart, in my application is a Datatable. I have a spinner to show the number of that product, and I want that when spinner value changes, refresh my shopping cart, this is my code:
<p:dataTable var="carro" value="#{productoBean.productos}">
<f:facet name="header">
<h:outputText value="Carrito de la Compra" />
</f:facet>
<p:column headerText="Producto">
<h:outputText value="#{carro.producto.nombre}" />
</p:column>
<p:column headerText="Cantidad">
<p:spinner value="#{carro.cantidad}">
<p:ajax listener="#{productoBean.refreshCantidad}" update="#this" />
</p:spinner>
</p:column>
<p:column headerText="Precio/Unidad">
<h:outputText value="#{carro.producto.precioUnidad} €" />
</p:column>
<p:column headerText="Valor">
<h:outputText value="#{carro.valor} €" />
</p:column>
</p:dataTable>
I don't know how get the item which spinner change and update its values.
Please I need help, Thanks in advance.
Greetings.

Answer 1

Finally I did:
<p:column headerText="Cantidad">
<p:spinner value="#{carro.cantidad}" valueChangeListener="#{productoBean.updateCantidad}">
<p:ajax event="change" listener="#{productoBean.refreshCantidad(carro)}" update=":formCarrito" />
</p:spinner>
</p:column>
In productoBean.updateCantidad I have:
public void updateCantidad(ValueChangeEvent event) {
cantidad = (Integer) event.getNewValue();
}
And in productoBean.refreshCantidad(carro) as can be seen, carro is the param of the method:
public void refreshCantidad(Compra compra) {
carritoBean.addProduct(compra.getProducto(), cantidad);
}
This way I know what's the last value of the spinner and I can update my shopping cart.
Greetings.