How to read flash attributes after redirection in Spring MVC 3.1?

Question

I would like to know how to read a flash attributes after redirection in Spring MVC 3.1.

I have the following code:

@Controller @RequestMapping("/foo") public class FooController {    @RequestMapping(value = "/bar", method = RequestMethod.GET)   public ModelAndView handleGet(...) {     // I want to see my flash attributes here!   }    @RequestMapping(value = "/bar", method = RequestMethod.POST)   public ModelAndView handlePost(RedirectAttributes redirectAttrs) {     redirectAttrs.addFlashAttributes("some", "thing");     return new ModelAndView().setViewName("redirect:/foo/bar");   }  } 

What I am missing?

Answer 1

Use Model, it should have flash attributes prepopulated:

@RequestMapping(value = "/bar", method = RequestMethod.GET) public ModelAndView handleGet(Model model) {   String some = (String) model.asMap().get("some");   // do the job } 

or, alternatively, you can use RequestContextUtils#getInputFlashMap:

@RequestMapping(value = "/bar", method = RequestMethod.GET) public ModelAndView handleGet(HttpServletRequest request) {   Map<String, ?> inputFlashMap = RequestContextUtils.getInputFlashMap(request);   if (inputFlashMap != null) {     String some = (String) inputFlashMap.get("some");     // do the job   } } 

P.S. You can do return return new ModelAndView("redirect:/foo/bar"); in handlePost.

EDIT:

JavaDoc says:

A RedirectAttributes model is empty when the method is called and is never used unless the method returns a redirect view name or a RedirectView.

It doesn't mention ModelAndView, so maybe change handlePost to return "redirect:/foo/bar" string or RedirectView:

@RequestMapping(value = "/bar", method = RequestMethod.POST) public RedirectView handlePost(RedirectAttributes redirectAttrs) {   redirectAttrs.addFlashAttributes("some", "thing");   return new RedirectView("/foo/bar", true); } 

I use RedirectAttributes in my code with RedirectView and model.asMap() method and it works OK.