SpringBoot DTO Validation

Question

I am new to spring-boot I'm trying to add validation to my DTO class like below.

import javax.validation.constraints.NotBlank;

@Getter
@Setter
public class EmployeeDto {
    private Long id;

    @NotBlank(message = "Employee first name is required")
    private String firstName;

    private String lastName;

    @NotBlank(message = "EmployeeNUM  is required")
    private String employeeNum;

}

Below is my REST endpoint to save employee.

import javax.validation.Valid;
 @PostMapping("/employee")
    public ResponseEntity<?> addEmployee(@Valid @RequestBody EmployeeDto employeeDto) throws ClassNotFoundException {
        return   ResponseEntity.ok(employeeService.saveEmployee(deptId,employeeDto));

    }

I create a Validation class like below to validate the DTO fields.

@ControllerAdvice
@RestController
public class Validation {

    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public Map<String, String> handleValidationExceptions(
            MethodArgumentNotValidException ex) {
        Map<String, String> errors = new HashMap<>();
        ex.getBindingResult().getAllErrors().forEach((error) -> {
            String fieldName = ((FieldError) error).getField();
            String errorMessage = error.getDefaultMessage();
            errors.put(fieldName, errorMessage);
        });
        return errors;

    }
}

expected output is

{ "firstName":"Employee first name is required", "employeeNum":"EmployeeNUM is required" }

But I'm getting only the 400 bad request when hit the endpoint through postman. What is the issue with my code? How to fix and get the expected output as mentioned above?

@SupunWijerathne Yes. I'm getting the status correctly but not the response body. — Dasitha Sandaruwan
– Dasitha Sandaruwan, Commented May 17, 2020 at 5:50
@SupunWijerathne still not working. I just followed the below document, doing the same thing for the entity class that class is annotated with the entity and its working I think the issue is DTO is not having entity annotation. we cannot add entity on DTO classes so is there another way to handle validations on DTO classes? baeldung.com/spring-boot-bean-validation — Dasitha Sandaruwan
– Dasitha Sandaruwan, Commented May 17, 2020 at 6:08

Ehab Qadah · Accepted Answer · 2020-05-17 18:02:01Z

Try to extend the ResponseEntityExceptionHandler class like this:


import org.apache.commons.collections4.CollectionUtils;
import org.apache.commons.lang3.StringUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;

import javax.validation.ConstraintViolationException;
import java.time.Instant;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;


/**
 * * Handle all exceptions and java bean validation errors for all endpoints income data that use the @Valid annotation
 *
 * @author Ehab Qadah
 */
@ControllerAdvice
public class GeneralExceptionHandler extends ResponseEntityExceptionHandler {


    @Override
    protected ResponseEntity<Object> handleMethodArgumentNotValid(MethodArgumentNotValidException exception, HttpHeaders headers,
                                                                  HttpStatus status, WebRequest request) {
        List<String> validationErrors = exception.getBindingResult()
                .getFieldErrors()
                .stream()
                .map(error -> error.getField() + ": " + error.getDefaultMessage())
                .collect(Collectors.toList());
        return getExceptionResponseEntity(HttpStatus.BAD_REQUEST, request, validationErrors);
    }


    @ExceptionHandler({ConstraintViolationException.class})
    public ResponseEntity<Object> handleConstraintViolation(
            ConstraintViolationException exception, WebRequest request) {
        List<String> validationErrors = exception.getConstraintViolations().stream().
                map(violation -> violation.getPropertyPath() + ": " + violation.getMessage())
                .collect(Collectors.toList());
        return getExceptionResponseEntity(HttpStatus.BAD_REQUEST, request, validationErrors);
    }

    private ResponseEntity<Object> getExceptionResponseEntity(final HttpStatus status, WebRequest request, List<String> errors) {
        final Map<String, Object> body = new LinkedHashMap<>();
        final String errorsMessage = CollectionUtils.isNotEmpty(errors) ? errors.stream().filter(StringUtils::isNotEmpty).collect(Collectors.joining(",")):status.getReasonPhrase();
        final String path = request.getDescription(false);
        body.put("TIMESTAMP", Instant.now());
        body.put("STATUS", status.value());
        body.put("ERRORS", errorsMessage);
        body.put("PATH", path);
        body.put("MESSAGE", status.getReasonPhrase());
        return new ResponseEntity<>(body, status);
    }
}

Satish Patro · Accepted Answer · 2022-02-01 12:15:09Z

I have copied the answer of @Ehab Qadah. Only one modification is giving error fields with reason in a map of string, instead of a string (fieldErrors variable)

    @ExceptionHandler({ConstraintViolationException.class})
public ResponseEntity<Object> handleConstraintViolation(
        ConstraintViolationException exception, WebRequest request) {
        
    Map<String, String> fieldErrors = ex.getConstraintViolations().stream()
            .collect(Collectors.toMap(cv -> cv.getPropertyPath().toString(), ConstraintViolation::getMessage));
        
    return getExceptionResponseEntity(HttpStatus.BAD_REQUEST, request, fieldErrors);
}

private ResponseEntity<Object> getExceptionResponseEntity(final HttpStatus status, WebRequest request, List<String> errors) {
    final Map<String, Object> body = new LinkedHashMap<>();
    final String errorsMessage = CollectionUtils.isNotEmpty(errors) ? errors.stream().filter(StringUtils::isNotEmpty).collect(Collectors.joining(",")):status.getReasonPhrase();
    final String path = request.getDescription(false);
    body.put("TIMESTAMP", Instant.now());
    body.put("STATUS", status.value());
    body.put("ERRORS", errorsMessage);
    body.put("PATH", path);
    body.put("MESSAGE", status.getReasonPhrase());
    return new ResponseEntity<>(body, status);
}

Dasitha Sandaruwan · Accepted Answer · 2020-05-17 07:34:39Z

-1

I used the below class and now it's working correctly.

@Service
public class MapValidationErrorService {
    public ResponseEntity<?> MapValidationService(BindingResult result){

        if(result.hasErrors()){
            Map<String, String> errorMap = new HashMap<>();

            for(FieldError error: result.getFieldErrors()){
                errorMap.put(error.getField(), error.getDefaultMessage());
            }
            return new ResponseEntity<Map<String, String>>(errorMap, HttpStatus.BAD_REQUEST);
        }

        return null;

    }

}

In COntroller

 @Autowired
    private MapValidationErrorService mapValidationErrorService;

    @PostMapping("/employee/{deptId}")
    public ResponseEntity<?> addEmployee(@PathVariable(name = "deptId") String deptId,@Valid @RequestBody EmployeeDto employeeDto, BindingResult result) throws ClassNotFoundException {
        ResponseEntity<?> errorMap = mapValidationErrorService.MapValidationService(result);
        if(errorMap != null)return errorMap;
        return   ResponseEntity.ok(employeeService.saveEmployee(deptId,employeeDto));

    }

answered May 17, 2020 at 7:34

Dasitha Sandaruwan

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2 Comments

Supun Wijerathne Over a year ago

This is pretty much unnecessary manual work. I'm sure your actual problem is something else.

M-Razavi Over a year ago

You don't need to validate manually, Sprint Boot validates the request body when you mention @valid. Don't forget to include spring-boot-starter-validation in dependencies.

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