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?

Grzegorz Rożniecki · Accepted Answer · 2012-08-01T17:13:14.990

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.

Did you try `RequestContextUtils.getInputFlashMap(request)`? — Grzegorz Rożniecki, Aug 01 '12 at 17:00
I will try with returning `RedirectView` then with `String`. — Rubens Mariuzzo, Aug 01 '12 at 17:22
Thanks, it just worked like a charm by returning a `RedirectView`. — Rubens Mariuzzo, Aug 01 '12 at 17:28

Jaffadog · Answer 2 · 2013-08-02T01:57:52.747

33

Try this:

@Controller
public class FooController
{
    @RequestMapping(value = "/foo")
    public String handleFoo(RedirectAttributes redirectAttrs)
    {
        redirectAttrs.addFlashAttribute("some", "thing");
        return "redirect:/bar";
    }

    @RequestMapping(value = "/bar")
    public void handleBar(@ModelAttribute("some") String some)
    {
        System.out.println("some=" + some);
    }
}

works in Spring MVC 3.2.2

edited Aug 02 '13 at 01:57

answered Aug 01 '13 at 19:50

Jaffadog

664
8
16

2

just note that you cannot check for "is the attribute filled" on custom objects. the `@ModelAttribute` returns not-null even if there is no object with given name in redirect attributes. – Ondrej Skalicka Dec 23 '16 at 09:01

logixplayer · Answer 3 · 2015-06-24T04:26:21.487

For all those like me who were having problems with seeing the POST url in the browser when a validation would fail.

The POST url is a private url that should not be exposed to users but it was automatically rendered when a validation failed. i.e. if a field was below a minimum length. I was using @Valid. I wanted the original GET url of the form to show at all times even when validation bounced back to the form, so I did the following:

        if (validation.hasErrors()) {

        redirectAttributes.addFlashAttribute("org.springframework.validation.BindingResult.story", validation);
        redirectAttributes.addFlashAttribute("story", story);
        return new ModelAndView("redirect:/january/2015");

where story is the form object representation, redirectAttributes are RedirectAttributes you put in the method signature and validation is the BindingResult. /january/2015 is the mapping to the GET controller where the form lives.

After this implementation, in the mapping for /january/2015, story comes in intact as follows:

Story story= (Story) model.asMap().get("story");
//story from the POST method

I had to augment my GET method and check if this was not null. If not null, then send this to the form else I would send a newly initialized Story type to the form as default behaviour before.

In this manner, I am able to return to the form with the bindingresults intact (errors show on form) but have my GET url in place of the post url.

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

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