Conditional validation in spring mvc - spring

Question

Now I have following controller method signature:
#ResponseBody
#RequestMapping(value = "/member/createCompany/addParams", method = RequestMethod.POST)
public ResponseEntity setCompanyParams(
#RequestParam("companyName") String companyName,
#RequestParam("email") String email,
HttpSession session, Principal principal) throws Exception {...}
I need to add validation for input parameters.
Now I am going to create object like this:
class MyDto{
#NotEmpty
String companyName;
#Email // should be checked only if principal == null
String email;
}
and I am going to write something like this:
#ResponseBody
#RequestMapping(value = "/member/createCompany/addParams", method = RequestMethod.POST)
public ResponseEntity setCompanyParams( MyDto myDto, Principal principal) {
if(principal == null){
validateOnlyCompanyName();
}else{
validateAllFields();
}
//add data to model
//return view with validation errors if exists.
}
can you help to achieve my expectations?

Answer 1

That's not the way Spring MVC validations work. The validator will validate all the fields and will put its results in a BindingResult object.
But then, it's up to you to do a special processing when principal is null and in that case look as the validation of field companyName :
#ResponseBody
#RequestMapping(value = "/member/createCompany/addParams", method = RequestMethod.POST)
public ResponseEntity setCompanyParams(#ModelAttribute MyDto myDto, BindingResult result,
Principal principal) {
if(principal == null){
if (result.hasFieldErrors("companyName")) {
// ... process errors on companyName Fields
}
}else{
if (result.hasErrors()) { // test any error
// ... process any field error
}
}
//add data to model
//return view with validation errors if exists.
}