Question

I want to validate a string against a set of values using annotations.

What I want is basically this:

@ValidateString(enumClass=com.co.enum)
String dataType;

int maxValue;
int minValue;
int precision;

or

@ValidateString(values={"String","Boolean", "Integer"})
String dataType;

int maxValue;
int minValue;
int precision;

I also want to do some validation on other variables depending upon the value set in dataType:

if (dataType = "String") {
    // maxValue, minValue, precision all should be null or zero
}

I can’t think of a way to achieve this by custom annotations.
Somebody please help me.

Answer 1

This is what I did.

Annotation

public @interface ValidateString {

    String[] acceptedValues();

    String message() default "{uk.dds.ideskos.validator.ValidateString.message}";

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

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

Validation Class

public class StringValidator implements ConstraintValidator<ValidateString, String>{

    private List<String> valueList;

    @Override
    public void initialize(ValidateString constraintAnnotation) {
        valueList = new ArrayList<String>();
        for(String val : constraintAnnotation.acceptedValues()) {
            valueList.add(val.toUpperCase());
        }
    }

    @Override
    public boolean isValid(String value, ConstraintValidatorContext context) {
        return valueList.contains(value.toUpperCase());
    }

}

And i used it like

@ValidateString(acceptedValues={"Integer", "String"}, message="Invalid dataType")
String dataType;

Long maxValue;
Long minValue;

Now I need to figure out how to implement conditional check
ie. if String then maxValue and minValue should be null or Zero..

Any ideas?