Submitting a POST object - spring

Question

I spent the whole weekend searching the net on my problem. It seems like I am missing something really silly, but I failed to pick it up.
Here's the problem. I sent an object to a JSP and on the JSP I could see its content. I them I submitted the form. Back in the controller, it shows the object is overwritten/recreated. I can't seem to understand. I checked the logs on my Tomcat but I do not see any error...
On my Controller:
#RequestMapping(value = {"/", "/home"}, method = RequestMethod.GET)
public String homePage(ModelMap model) {
model.addAttribute("user", getPrincipal());
Catalog catalog = catalogService.getCatalogByCategory(Catalog.CatalogCategory.ALL);
model.addAttribute("catalog", catalog);
model.addAttribute("numberOfItemsAdded", "500");
return "welcome";
}`
and in my JSP I have the following:
<form:form method="POST" modelAttribute="catalog">
<form:hidden path="id"/>
<div id="products" class="row list-group">
<c:forEach var="orderItem" items="${catalog.orderItems}">
<div class="item col-xs-4 col-lg-4">
<div class="thumbnail">
<img class="group list-group-image" src="http://placehold.it/400x250/000/fff" alt=""/>
<div class="caption">
<h4 class="group inner list-group-item-heading">
${orderItem.name}</h4>
<p class="group inner list-group-item-text">
${orderItem.description}
</p>
<div class="row">
<div class="col-xs-12 col-md-6">
<p class="lead">
R ${orderItem.price}</p>
</div>
<div class="col-xs-12 col-md-6">
<label for="${orderItem.id}" class="btn btn-primary">Add to Cart <input
type="checkbox" id="${orderItem.id}" name="orderItem.addedToCart"
class="badgebox"><span class="badge">&check;</span></label>
</div>
</div>
</div>
</div>
</div>
</c:forEach>
</div>
<div class="row">
<div class="form-group">
<div class="col-sm-12 pull-right">
</div>
<div class="col-sm-2 pull-right">
<input type="submit"
class="btn btn-default btn-block btn-primary"
value="Next" name="action" formmethod="POST"
formaction="confirmList"/>
</div>
</div>
</div>
</form:form>`
After pressing "Next", which submits the form data to a controller:
#RequestMapping(value = "/confirmList", method = RequestMethod.POST)
public String confirmList(#ModelAttribute Catalog catalog, #ModelAttribute String numberOfItemsAdded) {
System.out.println("\n\n------>catalog = " + catalog);
System.out.println("\n\n------>numberOfItemsAdded = " + numberOfItemsAdded);
List<OrderItem> selectedItems = new ArrayList<OrderItem>();
for (OrderItem orderItem : catalog.getOrderItems()) {
if (orderItem.isAddedToCart()) {
selectedItems.add(orderItem);
}
}
//model.addAttribute("numberOfItemsAdded", selectedItems.size());
return "welcome";
}
`
The System.out.println(...) output the following:
------>catalog = Catalog{id=1, name='null', category='null', orderItems=null}
------>numberOfItemsAdded =
Those are empty outputs.... :'(
I have no idea what I am doing wrong here.....

Answer 1

This was answered in a comment line by George. All I had to do is hide/bind those null fields.
It is very concerning that we use the term 'hidden' to also mean 'ignore' or 'leave as is'. But anyway, the solution above did exactly what I was looking for.
Thanks to the Community