spring mvc checking checkbox does not set object - spring

Question

Hi I am new to spring MVC and am trying to implement a form:checkboxes tag and have run into a few issues. All the examples I have googled work with Strings and i want to work with objects so am hoping someone can advise.
I have a List of objects set in my DTO as follows:
TestDTO
private List<Barrier> barriers;
public List<Barrier> getBarriers() {
return barriers;
}
public void setBarriers(List<Barrier> barriers) {
this.barriers = barriers;
}
in my controller class I fetch the barrier objects from the database and add them to my DTO which will be passed to the jsp
savedRecord.setBarriers(dataService.getBarriers());
mav.addObject("testDto", savedRecord);
in my JSP I use the form:checkboxes tag as follows:
<form:checkboxes path="barriers" items="${testDto.barriers}" element="label class='block-label'"
itemLabel="barrier"/>
I also tried with adding
itemValue="id"
but that did not work either
this is wraped in a from element
<form:form method="post" accept-charset="UTF-8" action="${action}"
onsubmit="return checkAndSend()" id="create"
novalidate="" modelAttribute="testDto">
So the issues I am having are as follows:
The checkboxes when displayed all seem to be checked. I have implemented a hashcode and equals method on the barrier object but they still all seem to be checked when I want them unchecked.
Barrier.java
#Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((barrier == null) ? 0 : barrier.hashCode());
result = prime * result + ((display == null) ? 0 : display.hashCode());
result = prime * result + id;
return result;
}
#Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Barrier other = (Barrier) obj;
if (barrier == null) {
if (other.barrier != null)
return false;
} else if (!barrier.equals(other.barrier))
return false;
if (display == null) {
if (other.display != null)
return false;
} else if (!display.equals(other.display))
return false;
if (id != other.id)
return false;
return true;
}
When I click submit and i look at the testDto my barriers object list is null. How do I get the checked boxes that represent objects to be set on my testDto.
Any pointers and advice is appreciated
Thanks
UPDATE:
Thanks for the pointers. I went with the following. your suggestion helped.
I created the folloiwng in my controller
#InitBinder
public void initBinder(WebDataBinder binder)
{
binder.registerCustomEditor(Barrier.class, new BarrierPropertyEditor(barrierService));
}
and then added a class to do the conversion
public class BarrierPropertyEditor extends PropertyEditorSupport {
private BarrierService barrierService;
public BarrierPropertyEditor(BarrierService barrierService) {
this.barrierService = barrierService;
}
#Override
public void setAsText(String text) {
Barrier b = barrierService.findById(Integer.valueOf(text));
setValue(b);
}
}
This sets the barrier objects on my DTO.
(Sorry for the caps) IT DOES NOT SOLVE WHY THE CHECKBOXES ARE CHECKED ON INITIAL LOAD.
Any ideas how to set the checkboxes unchecked on intitial load?

Answer 1

You can use #ModelAttribute in your Controller to provide the list of values in checkboxes.
#ModelAttribute("barrierList")
public List<Barrier> populateBarrierList() {
List<Barrier> barrierList = dataService.getBarriers();
for(Barrier barrier: barrierList )
{
barrierList.add(barrier);
}
return barrierList ;
}
In JSP, use following :
<form:checkboxes path="barriers" items="${barrierList}" element="label class='block-label'" itemLabel="barrier"/>