with respect to javax.validation
@NotNull(message = "From can't be null")
@Min(value = 1, message = "From must be greater than zero")
private Long from;
@NotNull(message = "To can't be null")
@Min(value = 1, message = "To must be greater than zero")
private Long to;
I want to also validate that FROM should be less than TO and TO should be greater than FROM ? how we can do this using javax validation's annotation ?
You need a custom cross field validation annotation.
One way is to annotate your custom class with @YourCustomAnnotation.
In YourCustomAnnotationValidator you have access to your value, hence you can implement your logic there:
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Constraint(validatedBy = DateValidator.class)
public @interface RangeCheck {
String message();
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
public class RangeCheckValidtor implements ConstraintValidator<RangeCheck, YourDto> {
@Override
public void initialize(RangeCheck date) {
// Nothing here
}
@Override
public boolean isValid(YourDto dto, ConstraintValidatorContext constraintValidatorContext) {
if (dto.getFrom() == null || dto.getTo() == null) {
return true;
}
return from < to;
}
}
Then mark your YourDto class with @RangeCheck:
@RangeCheck(message = "your messgae")
public class YourDto {
// from
// to
}
Or simply manually validate the relation of two fields.
For anyone who needs a more generic solution, validator can be implemented to compare two given property. Here is what I came up with :
@Target({ TYPE, ANNOTATION_TYPE })
@Retention(RUNTIME)
@Constraint(validatedBy = { CompareFieldsValidator.class })
public @interface CompareFields {
String message() default "{CompareFields.message}";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
String left();
String right();
int[] vals() default {0};
@Target({ TYPE, ANNOTATION_TYPE })
@Retention(RUNTIME)
public @interface List {
CompareFields[] value();
}
}
public class CompareFieldsValidator implements ConstraintValidator<CompareFields, Object> {
private static final Logger log = LoggerFactory.getLogger(FieldsEqualityValidator.class);
private String left;
private String right;
private Set<Integer> vals;
@Override
public void initialize(CompareFields constraintAnnotation) {
left = constraintAnnotation.left();
right = constraintAnnotation.right();
vals = Arrays.stream(constraintAnnotation.vals()).boxed().collect(Collectors.toSet());
}
@Override
public boolean isValid(Object value, ConstraintValidatorContext context) {
if (value == null)
return true;
try {
Class<?> clazz = value.getClass();
//get left operand as comparable
Field leftField = ReflectionUtils.findField(clazz, left);
leftField.setAccessible(true);
Object leftObj = leftField.get(value);
Comparable<Object> leftComparable = (Comparable<Object>)leftObj;
//get right operand
Field rightField = ReflectionUtils.findField(clazz, right);
rightField.setAccessible(true);
Object rightObj = rightField.get(value);
//null check : return true if both null
if(leftComparable == null) {
if(rightObj == null) {
return true;
} else {
context.buildConstraintViolationWithTemplate(context.getDefaultConstraintMessageTemplate())
.addPropertyNode(left).addPropertyNode(right);
return false;
}
}
//return true if compareTo result in vals array
if(vals.contains(leftComparable.compareTo(rightObj))) {
return true;
}else {
context.buildConstraintViolationWithTemplate(context.getDefaultConstraintMessageTemplate())
.addPropertyNode(left).addConstraintViolation();
return false;
}
} catch (Exception e) {
log.error("Cannot validate one of two field in '" + value + "'!", e);
return false;
}
}
}
//Usage: selling price must be smallar than or equal to list price
@CompareFields(left = "sellingPrice", right = "listPrice", vals = {-1,0})
public class InventoryDto{
...
}
//Usage: start time must be before finish time
@CompareFields(left = "startTime", right = "finishTime", vals = {-1})
public class GateLogDto{
...
}
