Spring MVC Request method 'POST' not supported -> HTTP 405

Question

Got stuck for ~4 hours wondering where is the mistake in Spring MVC/thymeleaf app.
My local goal is to render admin.html after submitting login/pass form at home page.

Controller:

@Controller
public class HomeController {
        @GetMapping("/")
        public String getHome(Model m) {
            m.addAttribute( "user",new User());
            return "/home";
        }
        @PostMapping("/")
        public String getSubmit(@ModelAttribute User user){

            return "/admin";
        }
}

home.html:

  <form action="#" th:action="@{/admin}" th:object="${user}" method="post">
            <p class="txt">Name: <input type="text" th:field="*{name}"/></p>
            <p class="txt">Password: <input type="text" th:field="*{password}"/></p>
            <p><input class="button" type="submit" value="Submit" />
                <input class="button" type="reset" value="Reset" /></p>
        </form >

User class:

@Data
@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;
    private String name;
    private String password;
    private boolean isAdmin;
    private String address;
}

So I have googled loads of ideas, removed spring security from pom.xml,
tried to use @RequestedMapping with RequestMethod.PUT , - no way , it doesn't work.

Answer 1

Your controller should be like this:

@Controller
public class HomeController {
    @GetMapping("/")
    public String getHome(Model m) {
        m.addAttribute("user", new User());
        return "/home";
    }

    @PostMapping("/admin")
    public String getSubmit(User user) {   
        return "/admin";
    }
}

home.html shoud be like:

<form action="@{/admin}" th:object="${user}" method="post">
    <p class="txt">Name: <input type="text" th:field="*{name}"/></p>
    <p class="txt">Password: <input type="text" th:field="*{password}"/></p>
    <p><input class="button" type="submit" value="Submit" />
    <input class="button" type="reset" value="Reset"/></p>
</form >