Spring-MVC 3.1: Forwarding A Request From One Controller Function To Another - spring-mvc

Question

I'm using Spring 3.1. I have a controller function that takes in a command object ( a data holder ) submitted via a FORM and does some processing :
#RequestMapping(value = "/results", method = RequestMethod.POST)
public String toResultsScreen(#ModelAttribute("ssdh") SearchScreenDataHolder ssdh,
BindingResult bindingResult,
ModelMap model,
HttpSession session) {
if (bindingResult.hasErrors()) {
logger.debug("Error returning to /search screen");
return "search";
}
netView = "results";
// do stuff
return nextView;
} // end function
Some user would like to programmatically make GET links to obtain information from our site and I would like to set up another handler that would handle that request. It would create a new installation of that the command object ( ssdh ) and populate it with the parameters sent via the GET request. Then it would pass it on to the handler above. Something like this:
#RequestMapping(value = "/pubresult")
public String toPublicResultsScreen(ModelMap model,
HttpSession session,
#RequestParam (required=true) String LNAME,
#RequestParam (required=false)String FNAME){
Search search = new Search(usertype);
// Capture the search parameters sent by HTTP
ssdh.setLast_name(LNAME);
ssdh.setFirst_name(FNAME);
// To Do: "forward this data holder, ssdh to the controller function quoted first
return nextView;
} // end function
My question is how can I forward my command/data holder object to the first controller function such that I don't have to alter the code to the first controller function in any way?

Answer 1

You can use RedirectAttributes object which was introduced in Spring MVC 3.1 and populate it with data you want to keep for redirection. It called PRG (POST/Redirect/GET) pattern.
#RequestMapping(value="/saveUserDetails.action", method=RequestMethod.POST)
public String greetingsAction(#Validated User user,RedirectAttributes redirectAttributes){
//setting attributes
redirectAttributes.addFlashAttribute("firstName", user.getFirstName());
redirectAttributes.addFlashAttribute("lastName", user.getLastName())
return "redirect:success.html";
}
I wrote some technical article regarding how to use it. I believe it will give you more details:
http://www.tikalk.com/java/redirectattributes-new-feature-spring-mvc-31

Answer 2

You should be able to set the ssdh in a ModelAttribute and simply forward it back, this way, the RequestDispatcher should be able to map it back to the /results handler:
#RequestMapping(value = "/pubresult")
public String toPublicResultsScreen(ModelMap model,
HttpSession session,
#RequestParam (required=true) String LNAME,
#RequestParam (required=false)String FNAME, Model model){
Search search = new Search(usertype);
// Capture the search parameters sent by HTTP
ssdh.setLast_name(LNAME);
ssdh.setFirst_name(FNAME);
model.addAttribute("ssdh", ssdh);
return "forward:/results";
}

Answer 3

Use
org.springframework.web.servlet.view.RedirectView
class from spring package to redirect to different page in spring MVC controller. The Baeldung blog page has more details
Sample code:
#RequestMapping(value = "/", method = RequestMethod.GET)
public RedirectView mainMethod() {
return new RedirectView("/login");
}
#RequestMapping(value = "/login", method = RequestMethod.GET)
public ModelAndView mainLogin() {
ModelAndView model = new ModelAndView("login");
return model;
}