RequestParam in Spring MVC handling optional parameters

Question

Is it possible for a Spring controller to handle both kind of requests    1  http   localhost 8080 submit id ID123432 logout true  2  http   localhost 8080 submit id ID123432 name sam amp password 543432  If I define a single controller of the kind     RequestMapping  value     submit id  id    method   RequestMethod GET      produces  text xml   public String showLoginWindow  PathVariable  id   String id                                 RequestParam value    logout   required   false  String logout                                 RequestParam  name   String username                                 RequestParam  password   String password                                 ModelAttribute  submitModel   SubmitModel model                                BindingResult errors  throws LoginException         the HTTP request with  logout  is not accepted   If I define two controllers to handle each request separately  Spring complains with the exception  There is already  Controller  bean method     mapped

User · Answer

As part of Spring 4 1 1 onwards you now have full support of Java 8 Optional  original ticket  therefore in your example both requests will go via your single mapping endpoint as long as you replace required false with Optional for your 3 params logout  name  password    RequestMapping  value     submit id  id    method   RequestMethod GET      produces  text xml   public String showLoginWindow  PathVariable  id   String id                                 RequestParam value    logout   Optional lt String gt  logout                                 RequestParam  name   Optional lt String gt  username                                 RequestParam  password   Optional lt String gt  password                                 ModelAttribute  submitModel   SubmitModel model                                BindingResult errors  throws LoginException

User · Answer

Create 2 methods which handle the cases  You can instruct the  RequestMapping annotation to take into account certain parameters whilst mapping the request  That way you can nicely split this into 2 methods     RequestMapping  value   submit id  id    method RequestMethod GET                    produces  text xml   params   logout    public String handleLogout  PathVariable  id   String id            RequestParam  logout   String logout            RequestMapping  value   submit id  id    method RequestMethod GET                    produces  text xml   params   name    password    public String handleLogin  PathVariable  id   String id   RequestParam  name            String username   RequestParam  password   String password            ModelAttribute  submitModel   SubmitModel model  BindingResult errors           throws LoginException

User · Answer

You need to give required   false for name and password request parameters as well  That s because  when you provide just the logout parameter  it actually expects for name and password as well as they are still mandatory   It worked when you just gave name and password because logout wasn t a mandatory parameter thanks to required   false already given for logout

[java] @RequestParam in Spring MVC handling optional parameters

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