做“model.addAttribute()”和“session.setAttribute()”的区别

Question

Can someone give me a clear difference in using "model.addAttribute()" and "session.setAttribute()"?

'''

@PostMapping("/auth")
    public String loginPost(@RequestParam String username,@RequestParam String password,Model model,HttpSession session) {
        SignupDTO signupDTO = signupService.authUser(username, password);
        if (signupDTO != null) {

            model.addAttribute("email", signupDTO.getEmail());
            model.addAttribute("name", signupDTO.getName());
            model.addAttribute("salutation", signupDTO.getSalutation());



            session.setAttribute("role", signupDTO.getRole());
            session.setAttribute("name", signupDTO.getName());
            session.setAttribute("email", signupDTO.getEmail());
            session.setAttribute("salutation", signupDTO.getSalutation());
            return "success";
        } else {
            model.addAttribute("message", "Sorry username and password are not correct!");
            return "login";
        }
    }

'''

Answer 1

The main difference is that model is per request while the session is per Http Session. That means every request will have a new model. A model will be destroyed after processing an request and a brand new model will be created for the next request.

So if you want the subsequent requests can access the value that you set in the previous requests in the same session, you have to add it to the session but not the model.