why Spring mvc redirect not working well? - spring

Question

#PostMapping("/regist")
public String regist(Person person, Model model) {
Person p = new Person("name", "age");
model.addAttribute("person", p); //add person to model
model.addAttribute("hobby", "reading);
return "redirect:/info";
}
#GetMapping("/info")
public String info() {
return "result";
}
Why (person) model.addAttribute("person", p) not appended to url like (hobby) when redirecting?

Answer 1

Model attributes are not used for redirects. Have a look at RedirectAttributes instead.
A specialization of the Model interface that controllers can use to
select attributes for a redirect scenario. Since the intent of adding
redirect attributes is very explicit -- i.e. to be used for a redirect
URL, attribute values may be formatted as Strings and stored that way
to make them eligible to be appended to the query string or expanded
as URI variables in org.springframework.web.servlet.view.RedirectView.
This interface also provides a way to add flash attributes. For a
general overview of flash attributes see FlashMap. You can use
RedirectAttributes to store flash attributes and they will be
automatically propagated to the "output" FlashMap of the current
request.
Example usage in an #Controller:
#RequestMapping(value = "/accounts", method = RequestMethod.POST)
public String handle(Account account, BindingResult result, RedirectAttributes redirectAttrs) {
if (result.hasErrors()) {
return "accounts/new";
}
// Save account ...
redirectAttrs.addAttribute("id", account.getId()).addFlashAttribute("message", "Account created!");
return "redirect:/accounts/{id}";
}
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.
After the redirect, flash attributes are automatically added to the
model of the controller that serves the target URL.