Spring - Redirect after POST (even with validation errors)

Since Spring 3.1 you can use RedirectAttributes. Add the attributes that you want to have available before doing the redirect. Add both, the BindingResult and the object that you are using to validate, in this case Register.

For BindingResult you will use the name: "org.springframework.validation.BindingResult.[name of your ModelAttribute]".

For the object that you are using to validate you will use the name of ModelAttribute.

To use RedirectAttributes you have to add this in your config file. Among other things you are telling to Spring to use some newer classes:

<mvc:annotation-driven />

Now the errors will be displayed wherever you are redirecting

@RequestMapping(value = "/submit", method = RequestMethod.POST)
public final String submit(@ModelAttribute("register") @Valid final Register register, final BindingResult binding, RedirectAttributes attr, HttpSession session) {

if (binding.hasErrors()) {
    attr.addFlashAttribute("org.springframework.validation.BindingResult.register", binding);
    attr.addFlashAttribute("register", register);
    return "redirect:/register/create";
}

return "redirect:/register/success";
}

In addition to Oscar's nice answer, if you are following that RedirectAttributes approach, do not forget that you are actually passing the modelAttribute to the redirected page. This means if you create a new instance of that modelAttribute for the redirected page (in a controller), you will lose the validation errors. So, if your POST controller method is something like this:

@RequestMapping(value = "/submit", method = RequestMethod.POST)
public final String submit(@ModelAttribute("register") @Valid final Register register, final BindingResult binding, RedirectAttributes attr, HttpSession session) {

if (binding.hasErrors()) {
    attr.addFlashAttribute("org.springframework.validation.BindingResult.register", binding);
    attr.addFlashAttribute("register", register);
    return "redirect:/register/create";
}

return "redirect:/register/success";
}

Then you will probably need to do a modification in your register create page GET controller. From this:

@RequestMapping(value = "/register/create", method = RequestMethod.GET)
public String registerCreatePage(Model model) {
    // some stuff
    model.addAttribute("register", new Register());
    // some more stuff
}

@RequestMapping(value = "/register/create", method = RequestMethod.GET)
public String registerCreatePage(Model model) {
    // some stuff
    if (!model.containsAttribute("register")) {
        model.addAttribute("register", new Register());
    }
    // some more stuff
}

Source: http://gerrydevstory.com/2013/07/11/preserving-validation-error-messages-on-spring-mvc-form-post-redirect-get/

I would question why you need the redirect. Why not just submit to the same URL and have it respond differently to a POST? Nevertheless, if you really want to do this:

@RequestMapping(value = "/submit", method = RequestMethod.POST)
public final String submit(
    @ModelAttribute("register") @Valid final Register register,
    final BindingResult binding,
    HttpSession session) {

    if (binding.hasErrors()) {
        session.setAttribute("register",register);
        session.setAttribute("binding",binding);
        return "redirect:/register/create";
    }

    return "redirect:/register/success";
}

Then in your "create" method:

model.put("register",session.getAttribute("register"));
model.put("org.springframework.validation.BindingResult.register",session.getAttribute("register"));

The problem is you're redirecting to a new controller, rather than rendering the view and returning the processed form page. You need to do something along the lines of:

String FORM_VIEW = wherever_your_form_page_resides

...

if (binding.hasErrors())
    return FORM_VIEW;

I would keep the paths outside of any methods due to code duplication of strings.

Spring - Redirect after POST (even with validation errors)

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