[java] Spring MVC Controller redirect using URL parameters instead of in response

I am trying to implement RESTful urls in my Spring MVC application. All is well except for handling form submissions. I need to redirect either back to the original form or to a "success" page.

@Controller
@RequestMapping("/form")
public class MyController {

    @RequestMapping(method = RequestMethod.GET)
    public String setupForm() {
        // do my stuff
        return "myform";
    }

    @RequestMapping(method = RequestMethod.POST)
    public String processForm(ModelMap model) {            
        // process form data

        model.addAttribute("notification", "Successfully did it!");
        return "redirect:/form";
    }
}

However as I read in the Spring documentation, if you redirect any parameters will be put into the url. And that doesn't work for me. What would be the most graceful way around this?

This problem is caused (as others have stated) by model attributes being persisted into the query string - this is usually undesirable and is at risk of creating security holes as well as ridiculous query strings. My usual solution is to never use Strings for redirects in Spring MVC, instead use a RedirectView which can be configured not to expose model attributes (see: http://static.springsource.org/spring/docs/3.1.x/javadoc-api/org/springframework/web/servlet/view/RedirectView.html)

RedirectView(String url, boolean contextRelative, boolean http10Compatible, boolean exposeModelAttributes)

So I tend to have a util method which does a 'safe redirect' like:

public static RedirectView safeRedirect(String url) {
    RedirectView rv = new RedirectView(url);
    rv.setExposeModelAttributes(false);
    return rv;
}

The other option is to use bean configuration XML:

<bean id="myBean" class="org.springframework.web.servlet.view.RedirectView">
   <property name="exposeModelAttributes" value="false" />
   <property name="url" value="/myRedirect"/>
</bean>

Again, you could abstract this into its own class to avoid repetition (e.g. SafeRedirectView).

A note about 'clearing the model' - this is not the same as 'not exposing the model' in all circumstances. One site I worked on had a lot of filters which added things to the model, this meant that clearing the model before redirecting would not prevent a long query string. I would also suggest that 'not exposing model attributes' is a more semantic approach than 'clearing the model before redirecting'.

If you don't want the success message in the URL, then one option is to put it in the session (in the processForm method) and then check for it (and remove it) in the setupForm method.

Edited to add: if this is a pain to do manually, then you could write a subclass of RedirectView that adds a "message" attribute and wraps the process of inserting it into the session. Not sure, though, if there's an easy way to wrap getting the message back out of the session...

Honestly, I don't think there's an easy answer -- the nature of an HTTP redirect is that state isn't carried over; if you want to maintain state anyway, you're stuck with the various usual ways to maintain state in web applications: the session, a cookie, a querystring...

Hey you can just do one simple thing instead of using model to send parameter use HttpServletRequest object and do this

HttpServletRequest request;
request.setAttribute("param", "value")

now your parametrs will not be shown in your url header hope it works :)

I had the same problem. solved it like this:

return new ModelAndView("redirect:/user/list?success=true");

And then my controller method look like this:

public ModelMap list(@RequestParam(required=false) boolean success) {
    ModelMap mm = new ModelMap();
    mm.put(SEARCH_MODEL_KEY, campaignService.listAllCampaigns());
    if(success)
        mm.put("successMessageKey", "campaign.form.msg.success");
    return mm;
}

Works perfectly unless you want to send simple data, not collections let's say. Then you'd have to use session I guess.

You can have processForm() return a View object instead, and have it return the concrete type RedirectView which has a parameter for setExposeModelAttributes().

When you return a view name prefixed with "redirect:", Spring MVC transforms this to a RedirectView object anyway, it just does so with setExposeModelAttributes to true (which I think is an odd value to default to).

@RequestMapping(path="/apps/add", method=RequestMethod.POST)
public String addApps(String appUrl, Model model, final RedirectAttributes redirectAttrs) {
    if (!validate(appUrl)) {
       redirectAttrs.addFlashAttribute("error", "Validation failed");
    }
    return "redirect:/apps/add"
} 

@RequestMapping(path="/apps/add", method=RequestMethod.GET)
public String addAppss(Model model) {
    String error = model.asMap().get("error");
}