[FIXED] How do I customize default error message from spring @Valid validation?

Issue

DTO:

public class User {

    @NotNull
    private String name;

    @NotNull
    private String password;

    //..
}

Controller:

@RequestMapping(value = "/user", method = RequestMethod.POST)
public ResponseEntity<String> saveUser(@Valid @RequestBody User user) {
    //..
    return new ResponseEntity<>(HttpStatus.OK);
}

Default json error:

{"timestamp":1417379464584,"status":400,"error":"Bad Request","exception":"org.springframework.web.bind.MethodArgumentNotValidException","message":"Validation failed for argument at index 0 in method: public org.springframework.http.ResponseEntity<demo.User> demo.UserController.saveUser(demo.User), with 2 error(s): [Field error in object 'user' on field 'name': rejected value [null]; codes [NotNull.user.name,NotNull.name,NotNull.java.lang.String,NotNull]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [user.name,name]; arguments []; default message [name]]; default message [may not be null]],"path":"/user"}

I would like to have my custom json for each error occured. How do I accomplish that?

Solution

You can perform validation with Errors/BindingResult object. Add Errors argument to your controller method and customize the error message when errors found.

Below is the sample example, errors.hasErrors() returns true when validation is failed.

@RequestMapping(value = "/user", method = RequestMethod.POST)
@ResponseBody
public ResponseEntity<String> saveUser(@Valid @RequestBody User user, Errors errors) {
    if (errors.hasErrors()) {
        return new ResponseEntity(new ApiErrors(errors), HttpStatus.BAD_REQUEST);
    }
    return new ResponseEntity<>(HttpStatus.OK);
}

Answered By - kswaughs
Answer Checked By - Gilberto Lyons (JavaFixing Admin)