How to generate JavaScript JSON object with jQuery?

[Joseph Hwang]

First below codes are my spring RESTful Server controller class.

@RestController
@RequestMapping(value="/rest/user")
public class UserRestController {

	@Autowired
	private UserService userService;
	
	@PostMapping("login")
	public ResponseEntity<Boolean> authenticated(@RequestBody User user) {
		
		System.out.println(user.getUsername() + user.getPassword()); //This line returns NULL password value
		
		Boolean blogin = userService.authenticate(user.getUsername(), user.getPassword());
		if(!blogin)
			return new ResponseEntity<Boolean>(blogin, HttpStatus.NOT_ACCEPTABLE);
		
		return new ResponseEntity<Boolean>(blogin, HttpStatus.OK);
	}
}

And the following codes are Ajax Java script with jquery.

function ajax_login_submit() { var user = { username: $("#username").val(), password: $("#password").val() };        console.log(user.username);    console.log(user.password);    console.log(user);    $.ajax({ type: "POST", contentType: "application/json; charset=utf-8", url: "rest/user/login", data: JSON.stringify(user), dataType: 'json', success: function (data) {            var resultJson = JSON.stringify(data);            $('#helloUserDiv').html(resultJson);            console.log("SUCCESS : ", data);            alert(data);        },        error: function (e) {            var resultJson = e.responseText;            $('#helloUserDiv').html(resultJson);            console.log("ERROR : ", e);        } }); }

The console.log(user); in java script prints below value.

{username: "joseph", password: "password"}

But

System.out.println(user.getUsername() + ":" + user.getPassword());

in restcontroller prints the following value.

joseph:null

I am afraid the generated json value of jquery javascript bring some error. But I hava no idea how to make proper json type value.
Any idea will be deeply appreciated. Thansk.

[Bear Bibeault]

JSON.stringify() is not a jQuery API, so if there were an error in generating the JSON (unlikely), the problem would not be with jQuery.

If this were my problem I'd be using the browser tools to see the request that is being sent to make sure that it contains what is expected. If it does not, then the problem would be somewhere on the front end while generating the request. If the request is as expected, the problem is likely on the back-end, perhaps with the REST mappings.