Reference Data is lost from Form when Validation Fails (Spring 3 MVC) - spring

Question

I am new to Spring
I am having a page addContact,in that I am getting dropDown Data from Database in the following way
#RequestMapping("/addContact")
public ModelAndView registerContact(#ModelAttribute Contact contact) {
List<ContactType> contactTypeList = contactdao.getContactTypeList();
Map<Integer,String> contactTypeSelect = new LinkedHashMap<Integer,String>();
Iterator<ContactType> iterator = contactTypeList.iterator();
while (iterator.hasNext()) {
ContactType ct = iterator.next();
contactTypeSelect.put(ct.getContactTypeId(),ct.getContactTypeName());
}
Map<String, Object> map = new HashMap<String, Object>();
map.put("contactTypeSelect", contactTypeSelect);
return new ModelAndView("addContact", "map", map);
}
Now to Insert the Data into Database, I am having following method,
#RequestMapping("/insert")
public String insertData(#Valid Contact contact, BindingResult result, HttpServletRequest request ) {
if (result.hasErrors()) {
return "addContact";
}
else {
HttpSession session = request.getSession();
session.setAttribute("path", request.getSession().getServletContext().getRealPath("/WEB-INF"));
if (contact != null){
contactService.insertData(contact,request);
}
return "redirect:/getList";
}
}
When the validation fails, the drop down data is lost (which is obvious), what is the correct way of achieving the validation.

Answer 1

Create a method annotated with #ModelAttribute which loads the reference data. This method will be called before each #RequestMapping method.
#ModelAttribute("contactTypeSelect")
public List<ContactType> registerContact() {
return contactdao.getContactTypeList();
}
In your form you can use the <form:select ../> tag to render the itemValue and itemLabel.
<form:select items="${contactTypeSelect}" itemLabel="contactTypeName" itemValue="contactTypeId" />
With this you can refactor your addContact method to the following
#RequestMapping("/addContact")
public String registerContact(#ModelAttribute Contact contact) {
return "addContact";
}

Answer 2

You lose the drop down data because you're not adding in the contact map in the insertData method. Pull out the code where you grab the contact data into a separate (private) method and use it in the result.hasErrors() if block as such:
if (result.hasErrors()) {
return new ModelAndView("addContact", "map", map);
}
Also, I strongly suggest adding a method to the #RequestMapping annotation as such:
#RequestMapping("/insert", method=RequestMethod.POST)
This keeps people from making GET calls to this method.