How to bind validation errors to a request using MultiActionController?

Question

I've tried a lot to implement a validation inside a MultiActionController and it seems it's not plain sailing. I need to validate a form and, in case of failure, I want to redirect to the same form, displaying the errors and also being able to load some info from a database. So basically I have this:

@RequestMapping("/addResponse.htm")
public ModelAndView addResponse(@ModelAttribute("responseDTO") ResponseDTO
             respDTO, BindingResult result, HttpServletRequest request) { 

 ResponseFormValidator respValidator = new ResponseFormValidator();
 respValidator.validate(respDTO, result);

 if (result.hasErrors()) {
  return new ModelAndView("redirect:responseForm.htm?id=" + respDTO.getProjID());
 }
}

What I want is for the responseForm handler method to remember the errors resulted from the validation process (the Result Object) Of course, I can copy and paste the logic from that method inside my if statement but I'm thinking it must be a better way than just copy and paste.

Any help will be highly appreciated!

Answer 1

In Spring version prior to 3.1.x, if you want to pass object through a redirect, you have to make your controller "session" aware. http://static.springsource.org/spring/docs/2.5.x/reference/portlet.html#portlet-controller (part 16.9, look for @SessionAttribute)

But after it is your responsibility to clean the object(s) stored in session that you do not want to use anymore.

With Spring 3.1.x, the flashAttribute is a very useful mecanism and Spring does the job for that.

http://static.springsource.org/spring/docs/current/spring-framework-reference/html/mvc.html#mvc-flash-attributes

Hereunder a little code to show the principle:

@RequestMapping(value = "form", method = RequestMethod.GET)
public String showForm(@ModelAttribute("form") FormBean formBean) {

    // Set some properties if needed

    return "tiles-litools-mml";
}

@RequestMapping(value = "form", method = RequestMethod.POST)
public String formAction( @Validated({MyValidator.class})
    @ModelAttribute("form") FormBean formBean,
    BindingResult validatorresult, Model model, Errors errors,
    RedirectAttributes redirectAttributes) {

    //redirect if any error
    if (validatorresult.hasErrors()){

        redirectAttributes.addFlashAttribute("message", "MML session failed");
        redirectAttributes.addFlashAttribute("form", formBean);
        redirectAttributes.addFlashAttribute("validation", validatorresult);
        return "redirect:/app/tools/form"; // redirect to the form GET method

    }

    // TODO continue code for process the form (valid!)


} 

I assume you do not extends MultiActionController.