Spring MVC Controller redirect using URL parameters instead of in response.

Question

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?

Answer 1

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).

Answer 2

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...

Answer 3

http://jira.springframework.org/browse/SPR-6464 provided me with what I needed to get things working until Spring MVC offers the functionality (potentially in the 3.0.2 release). Although I simply implemented the classes they have temporarily and added the filter to my web application context. Works great!