JSR 303 Bean Validation: @ValidateDateRange - A reusable constraint annotation to validate date ranges

In a previous blog-post, I have described my experience on JSR 303 Bean Validation, and in the process, this @ValidateDateRange constraint annotation came upon into my mind. I thought that it would be useful so it inspired me to create its implementation and eventually made this blog-post.

The @ValidateDateRange is a class-level constraint annotation that will validate a date range represented by two java.util.Date properties of an object. This can be reused in any class.

@ValidateDateRange(start="startDate", end="endDate")
public class MyEntity {
   private Date startDate;
   private Date endDate;
   ...
}

The annotation definition are as follows:

package blogspot.soadev.validator;

import static java.lang.annotation.ElementType.*;
import static java.lang.annotation.RetentionPolicy.*;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import java.util.Date;

import javax.validation.Constraint;
import javax.validation.ConstraintPayload;

@Target( { TYPE, ANNOTATION_TYPE })
@Retention(RUNTIME)
@Constraint(validatedBy = {DateRangeValidator.class} )
@Documented

public @interface ValidateDateRange {
    String message() default "{end} should be later than {start}";
    String start();
    String end();
    Class[] groups() default {};
    Class[] payload() default {};       
}

And the implementing DateRangeValidator are as follows:

package blogspot.soadev.validator;

import java.lang.reflect.Field;
import java.util.Date;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;

public class DateRangeValidator implements ConstraintValidator{
    private String start;
    private String end;
    
    public void initialize(ValidateDateRange validateDateRange) {
        start = validateDateRange.start();
        end =  validateDateRange.end();
    }

    public boolean isValid(Object object,
                           ConstraintValidatorContext constraintValidatorContext) {
        try {
            Class clazz = object.getClass();
            Date startDate = null;
            Method startGetter = clazz.getMethod(getAccessorMethodName(start), new Class[0]);
            Object startGetterResult = startGetter.invoke(object, null);
            if (startGetterResult != null && startGetterResult instanceof Date){
                startDate = (Date) startGetterResult;
            }else{
                return false;
            }
            Date endDate = null;
            Method endGetter = clazz.getMethod(getAccessorMethodName(end), new Class[0]);
            Object endGetterResult = endGetter.invoke(object, null);
            if (endGetterResult == null){
                return true;
            }
            if (endGetterResult instanceof Date){
                endDate = (Date) endGetterResult;
            }
            return (startDate.before(endDate));           
        } catch (Throwable e) {
            System.err.println(e);
        }

        return false;
    }
    private String getAccessorMethodName(String property){
        StringBuilder builder = new StringBuilder("get");
        builder.append(Character.toUpperCase(property.charAt(0))); 
        builder.append(property.substring(1));
        return builder.toString();
    }
}

Related Posts

• JSR 303 Bean Validation: @AssertMethodAsTrue - A reusable constraint annotation that spans multiple properties.
• JSR 303 Bean Validation: Error "java.lang.NoSuchMethodError: javax.persistence.Persistence.getPersistenceUtil()Ljavax/persistence/PersistenceUtil;"
• Integrating JSR 303 Bean Validation with Oracle ADF 11g

Cheers!