Question

I have been looking for a way to make form validation as easy and unobtrusive as possible in Spring MVC 3. I like the way spring can handle Bean Validation by passing @Valid to my model (that has been annotated with validator annotations) and using the result.hasErrors() method.

I am setting up my controller actions like this:

@RequestMapping(value = "/domainofexpertise", method = RequestMethod.PUT)
public String addDomainOfExpertise(@ModelAttribute("domainOfExpertise") 
@Valid DomainOfExpertise domainOfExpertise, final BindingResult result) {

    if (result.hasErrors()) {
        return "/domainofexpertise/add";
    } else {
        domainOfExpertiseService.save(domainOfExpertise);
        return "redirect:/admin/domainofexpertise/list";
    }
}

Which works like a charm. Database exceptions (like trying to save something with a unique constraint on a field) will still get through. Is there any way to incorporate catching those exceptions in the validation process going on behind the scenes? This way of validating is very concise so I want to avoid having to manually catch them in my controller.

Any information on this?

Answer 1

Here is an example I use to convert PersistentExceptions to a friendlier message. It is a method that goes in the Controller. Will this work for you?

/**
 * Shows a friendly message instead of the exception stack trace.
 * @param pe exception.
 * @return the exception message.
 */
@ExceptionHandler(PersistenceException.class)
@ResponseBody
@ResponseStatus(HttpStatus.BAD_REQUEST)
public String handlePersistenceException(final PersistenceException pe) {
    String returnMessage;
    if (pe.getCause()
            instanceof ConstraintViolationException) {
        ConstraintViolationException cve =
                (ConstraintViolationException) pe.getCause();
        ConstraintViolation<?> cv =
                cve.getConstraintViolations().iterator().next();
        returnMessage = cv.getMessage();
    } else {
        returnMessage = pe.getLocalizedMessage();
    }
    if (pe instanceof EntityExistsException) {
        returnMessage = messages.getMessage("user.alreadyexists");
    }
    return returnMessage;
}