是否有机会验证请求正文中 DTO Object 的所有值是 null

Question

@Controller......

@PutMapping(value = "/{id}")
    public ResponseEntity<JsonNode> editStudent( @PathVariable @Positive(message = "Student id must be Positive Value") Long id, @Valid @ValidRequestBody(DTOClass = StudentDTO.class) @Validated(value = Update.class) @RequestBody(required = true) StudentDTO studentDTO, BindingResult bindingResult ) {.....

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@Documented
@Retention(RUNTIME)
@Target({ TYPE, ElementType.METHOD, ElementType.PARAMETER, ElementType.ANNOTATION_TYPE, ElementType.CONSTRUCTOR, ElementType.FIELD, ElementType.LOCAL_VARIABLE, ElementType.MODULE, ElementType.PACKAGE, ElementType.TYPE_PARAMETER, ElementType.TYPE_USE })
@Constraint(validatedBy = RequestBodyValidator.class)
public @interface ValidRequestBody {

    String message()

    default "Required parameter is missing";

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};

    Class<?> DTOClass();
}

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public class RequestBodyValidator implements ConstraintValidator<ValidRequestBody, Map<String, Object>> {

    Class<?> dtoClass = null;

    @Override
    public void initialize( ValidRequestBody constraintAnnotation ) {

        this.dtoClass = constraintAnnotation.DTOClass();
    }

    @Override
    public boolean isValid( Map<String, Object> objectNode, ConstraintValidatorContext context ) {

        Collection<Object> objectValues = objectNode.values();

        return !objectValues.stream().allMatch( null );
    }
}

Answer 1

You could use @NotNull over all fields https://www.baeldung.com/java-bean-validation-not-null-empty-blank

Answer 2

You can use @Valid or @NonNull annotation on all fields in your DTO. So, if a field is received as null or empty, exception would be thrown.