How to send JSON response from controller? - spring

Question

I want to pass a boolean value from my controller to javascript using json but couldnot find a way as I am new to spring mvc.
While using servlet we wrote:
response.getWriter().println(somevalue)
and the somevalue can be received using ajax.
Here my controller method is:
#RequestMapping(value = REGISTERACTION , method = RequestMethod.POST)
#ResponseBody
public boolean RegisterUser(#ModelAttribute("register") Register register,HttpServletRequest request, HttpServletResponse response)
{
boolean Registrationsuccess = userService.RegisterUser(register);
return Registrationsuccess;
}
So, here the boolean variable is Registrationsuccess which I want to send to js file and receive it using ajax.
And in my javascipt function which is called using onsubmit event-->
function AccountExists()
{
$.ajax({
type: 'POST',
url: 'registerProcess',
success: function(data){
let detail = JSON.parse(data);
if( data == true)
alert("Success");
else
alert("Not ");
}
});
}
Getting error --
The target resource does not have a current representation that would be acceptable to the user agent, according to the proactive negotiation header fields received in the request, and the server is unwilling to supply a default representation.

Answer 1

You need to use ResponseEntity and #RestController for JSON Response.
Note : #RestController includes both annotations #Controller and #ResponseBody.
Try with this :
#RestController
#RequestMapping("controller")
public class Controller {
#PostMapping("REGISTERACTION")
public ResponseEntity<Boolean> RegisterUser(#ModelAttribute("register") Register register)
{
Boolean registrationSuccess = userService.RegisterUser(register);
return new ResponseEntity<Boolean>(registrationSuccess , HttpStatus.OK);
}
}

Answer 2

Try to use #ResponseBody annotation in your controller's method. And change the return type of the method to Boolean, then return Registrationsuccess instead of ModelAndView.

Answer 3

You can achieve this using 2 approach
Approach 1: Set model attribute and using expression language you can find on jsp
model.addAttribute("test",true);
in Jsp page
${test}
Approach 2: If you are sending ajax request instead of ModelAndView create a object
set any attribute boolean and return object from method #ResponseBody annotation you will get json in Ajax Response
#RequestMapping(value = REGISTERACTION , method = RequestMethod.POST)
public #ResponseBody MyCustomObject RegisterUser(#ModelAttribute("register") Register register,HttpServletRequest request, HttpServletResponse response)
{
boolean Registrationsuccess = userService.RegisterUser(register);
MyCustomObject cusobj=new MyCustomObject();
cusobj.setStatus(true);
return cusobj;
}
Whatever code you have written it will not return json(It is basically form submission approach) so you have to go with first approach.