Question

I have a spring controller UserController and I have the following methods (business logic not included):

    @RequestMapping(value = "new", method = RequestMethod.GET)
public String getNewUserForm(Model model) {
    model.addAttribute("action", "Create");
    model.addAttribute(new User());
    return "users/edit";
}

@RequestMapping(value = "create", method = RequestMethod.POST)
public String getCreateUser(@ModelAttribute("user") User user, BindingResult result, RedirectAttributes attr) {
    attr.addFlashAttribute("user", user);
    return "redirect:view";
}

@RequestMapping(value = "view", method = RequestMethod.GET)
public String getViewUser(Model model) {
    return "users/view";
}

I end up with three “actions” (new, create, and view). What I want to achieve is the following: app.com/users/new is entered in the browser. The create user form users/edit is displayed. When the form is submitted, it calls users/create (POST). When the user is created successfully, I would like to forward the user to users/view, and display the input data in a non-editable page. I can’t just return view because then the url remains app.com/users/create. I’d like for it to read app.com/users/view.

Right now, I’m using a RedirectAttributes object, combined with returning redirect:view and it works. But it feels like there should be a better way to accomplish this. I tried using redirect:view without RedirectAttributes and the model wasn’t available.

The other alternative is to pass the user id in the url (for example: app.com/users/view/1) and load up the data from the database. But that seems like an unnecessary round trip to the database, considering I already have the latest version of the object. I will be implementing this for “pretty urls”, but I wan’t to have the option to not load the user object if it’s available.

Something like this:

    @RequestMapping(value = "view", method = RequestMethod.GET)
public String getViewUser(Model model, @RequestParam(required = false) String id) {

    if(!model.containsAttribute("user")){
        //get it from the db with the optional request parameter
    }

    return "users/view";
}

Is my approach recommended? Or am I looking at this completely wrong?

Answer 1

The better way is to redirect to app.com/users/view/1.

First because you have the latest changes you did to the model, but not the ones another concurrent user might have done concurrently.

Second because it makes your app stateless, thus more scalable and simpler at the same time.

Third because the view page might need more information about the user than the edit page does. It’s pretty frequent to have a large detail page showing many associations of the user, but have only some modifiable information in the edit page. So saving the model of the edit page to make it available to the view page won’t be sufficient.

Fourth because this way, the logic to show the detail of a user is at a single place, and there is only one possible URL to do that.

Fifth because this way, the user can bookmark the URL, or send it to someone by email, and it will work if he comes back later to this URL. Whereas in your current solution, the URL only works if you’ve edited the user just before.