User user = new User(username, password, email);

    model.addAttribute("user", user);


    if (username == null || password == null || email == null) {

        // Paramenters are required.

        return "newuser";

    }

    else if (username.equals(daoUser.findByUsername(username).getUsername())) {

        // Username already taken.

        return "newuser";
    }

    else {

        // User saved in database.

        daoUser.save(user);

        return "homepage";

    }

}