Spring MVC set attribute to request/model/modelMap

Question

I use Spring MVC. I need to add attribute to request or other object. It should be message that will display on screen. For example, if I use pure Servlets I may just:

request.setAttribute("message", "User deleted");

and than on JSP page

<div id="message">${message}</div>

but when I try to do something like this in method:

@RequestMapping(value = "/delete", method = RequestMethod.GET)
public String deleteUser(@RequestParam("login") String login,
        ModelMap map, HttpServletRequest request)

Model object -

model.addAttribute("message", "User deleted");

Map -

map.put("message", "User deleted");

ModelMap -

map.put("message", "User deleted");

HttpServletRequest -

request.setAttribute("message", "User deleted");

nothing displays. But in my browser I see: http:// localhost : 8081 /project/index?message=User+deleted

How to solve this little problem? Thanks for your answers

Updated:

for clear understanding I try to do this:

 @RequestMapping(value = "/delete", method = RequestMethod.GET)
public String deleteUser(@RequestParam("login") String login,
        Model model) {
    dao.delete(login); // there is NO exeptions
    map.addAttribute("message", "User " + login + " deleted");
    return "redirect:" + "index";
}

in my JSP I also display user login this way:

${user.login}

it takes user from Session and I see it login

it is "redirect:". I think that problem is in this redirection. So how I can redirect and send message? — Oleksandr H
– Oleksandr H, Commented Sep 24, 2013 at 14:29

Sotirios Delimanolis · Accepted Answer · 2013-09-24 14:32:11Z

20

With your new information, the problem is redirect:. When you do a redirect, you send an HTTP response with a 302 (or 301) response code with a Location header pointing to the new url. The browser will make a new HTTP request to that location. As such, your request attributes (and model attributes) are no longer good, they don't exist in the new request.

Consider use flash attributes. The RedirectAttributes class is the way to go. The javadoc has a good example.

A Model attribute is added to the request attributes much later during request processing. You therefore won't see it directly doing this

@RequestMapping(value = "/delete", method = RequestMethod.GET)
public String deleteUser(@RequestParam("login") String login,
        ModelMap map, HttpServletRequest request)
    map.put("message", "User deleted");
    String message = (String) request.getAttribute("message"); // will return null
    ...
}

Just trust that it will eventually be in the request attributes and therefore available in your jsp.

edited Sep 24, 2013 at 14:32

answered Sep 24, 2013 at 14:11

Sotirios Delimanolis

281k62 gold badges718 silver badges744 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Oleksandr H Over a year ago

Yes!! Thats it! i use attr.addFlashAttribute("message", "User deleted") of RedirectAttributes object. Thanks

Oleksandr H Over a year ago

I have a question. How I can do the same in pure Servlets? (without any Spring)

Sotirios Delimanolis Over a year ago

@OleksandrHubachov The underlying implementation uses HttpSession attributes. With pure Servlets you could use a Filter to add and remove from the HttpSession attributes on each request. There's an example here.

Debojit Saikia · Accepted Answer · 2013-09-24 14:46:09Z

8

As you are redirecting to a new URL, browser is actually sending a new request to the redirect URL. And the request attribute map.addAttribute("message", "User " + login + " deleted"); is not present in the new request.

You can use RedirectAttributes to show the message to the user:

@RequestMapping(value = "/delete", method = RequestMethod.GET)
public String deleteUser(@RequestParam("login") String login,
        Model model,RedirectAttributes redirectAttributes) {
    dao.delete(login); // there is NO exeptions
    //map.addAttribute("message", "User " + login + " deleted");
    redirectAttributes.addFlashAttribute("message", "User " + login + " deleted");
    return "redirect:" + "index";
}

redirectAttributes.addAttribute constructs request parameters out of your attributes and redirects to the desired page with the request parameters. And addFlashAttribute stores the attributes in a flashmap (maintained in the users session and removed once the next redirected request gets fulfilled).

edited Sep 24, 2013 at 14:46

answered Sep 24, 2013 at 14:31

Debojit Saikia

10.7k3 gold badges37 silver badges46 bronze badges

6 Comments

Oleksandr H Over a year ago

unfortunately, this does not work... I do not know why. As well as last time, I see in browser http:// localhost : 8081 /project/index?message=User+ololo+deleted

Debojit Saikia Over a year ago

try this : <c:out value="${message}" />

Sotirios Delimanolis Over a year ago

@DebojitSaikia You need to use addFlashAttribute.

Oleksandr H Over a year ago

Thanks for your answer. But in my case I need to call addFlashAttribute method of RedirectAttributes class

Skizo-ozᴉʞS ツ Over a year ago

@DebojitSaikia ya it helped, but what about if I want now to delete this flashAttribute? how do I delete it? I added null on this FlashAttribute... it works but it's kinda nasty

|

Jimmy · Accepted Answer · 2014-09-26 12:05:11Z

0

You are redirecting it in a wrong way. instead of return "redirect:"+"index" use return "redirect:/index". redirect it to your get method. as redirectattributes are post/redirect/get attribute. try this and you will get a flash message on your screen. instead of Model use Redirectattributes.

redirectAttributes.addFlashAttribute("errormsg", "errormessage"); return "redirect:/index.do";

answered Sep 26, 2014 at 12:05

Jimmy

1,8713 gold badges22 silver badges34 bronze badges

Collectives™ on Stack Overflow

Spring MVC set attribute to request/model/modelMap

3 Answers 3

3 Comments

6 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

6 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related