Get variable data in Hbrn Validator to show in error msg

MiLLeN · **Joined:** Thu Jan 15, 2009 6:41 am **Posts:** 9

I am development one Hibernate constraint to validate extension file. The question is I could want show in message error the bad upload file extension.

Now i have constraint look like this.

Enum to valid data.

Code:

    public enum FileType {
        JPG, PNG, GIF, BMP;
    }

Contraint.

Code:

    @Target({METHOD, FIELD, ANNOTATION_TYPE})
    @Retention(RUNTIME)
    @Constraint(validatedBy = CheckFileTypeValidator.class)
    @Documented
    public @interface CheckFileType {
    
        String message() default "{CheckFileType}";
    
        Class<?>[] groups() default {};
    
        Class<? extends Payload>[] payload() default {};
        
        FileType[] types();
        
    }

Validator.

Code:

    public class CheckFileTypeValidator implements ConstraintValidator<CheckFileType, MultipartFile> {
    
        private FileType[] types;
    
        @Override
        public void initialize(CheckFileType checkFileType) {
    
            this.types = checkFileType.types();
        }
    
            @Override
            public boolean isValid(MultipartFile multipartFile, ConstraintValidatorContext constraintValidatorContext) {
        
                for (int x = 0; x < this.types.length; x++) {
        
                    if (multipartFile.getContentType().toLowerCase().contains(this.types[x].toString().toLowerCase())) {
    
                        return true;
                    }
        
                }
        
                return false;
            }
            
        }

To use it.

Code:

    @CheckFileType(types = {FileType.JPG, FileType.PNG})
    private MultipartFile credential;

Now, What do I need to do to implement this feature?

Gunnar · **Joined:** Sat Jan 24, 2009 12:46 pm **Posts:** 388

If you are using Bean Validation 1.1 / Hibernate Validator 5.x, you can refer to the validated value within a Unified EL script expression:

Code:

@CheckFileType(
    types = {FileType.JPG, FileType.PNG},
    message = "Expected type to be one of {types} but was ${validatedValue.getContentType().toLowerCase()}."
)
private MultipartFile credential;

Here, "validatedValue" is the reserved name under which the validated object is made available to EL interpolation (the reference guide has some more details:
http://docs.jboss.org/hibernate/stable/validator/reference/en-US/html_single/#section-interpolation-with-message-expressions).

If you're still on Bean Validation 1.0, you could add a custom violation via the ConstraintValidatorContext like this:

Code:

...
@Override
public boolean isValid(MultipartFile multipartFile, ConstraintValidatorContext constraintValidatorContext) {
    boolean isValid = ...;

    if ( !isValid ) {
        constraintContext.disableDefaultConstraintViolation();
        constraintContext.buildConstraintViolationWithTemplate(
            "Expected type to be one of " + Arrays.toString( types ) +
            " but was " + multipartFile.getContentType().toLowerCase() + "."
        )
        .addConstraintViolation();
    }

    return isValid;
}
...

You can find more details on using ConstraintValidatorContext at http://docs.jboss.org/hibernate/stable/validator/reference/en-US/html_single/#validator-customconstraints-validator.

Hth,

--Gunnar