Generating a error code per property in Hibernate Validator

Question

I am looking at using Hibernate Validator for a requirement of mine. I want to validate a JavaBean where properties may have multiple validation checks. For example:

class MyValidationBean
{
   @NotNull
   @Length( min = 5, max = 10 )
   private String myProperty;
}

But if this property fails validation I want a specific error code to be associated with the ConstraintViolation, regardless of whether it failed because of @Required or @Length, although I would like to preserve the error message.

class MyValidationBean
{
   @NotNull
   @Length( min = 5, max = 10 )
   @ErrorCode( "1234" )
   private String myProperty;
}

Something like the above would be good but it doesn't have to be structured exactly like that. I can't see a way to do this with Hibernate Validator. Is it possible?

Answer 1

From the section 4.2. ConstraintViolation of the specification:

The getMessageTemplate method returns the non-interpolated error message (usually the message attribute on the constraint declaration). Frameworks can use this as an error code key.

I think this is your best option.

Answer 2

What I would try to do is isolate this behavior on the DAO Layer of the application.

Using your example we would have:

public class MyValidationBeanDAO {
    public void persist(MyValidationBean element) throws DAOException{
        Set<ConstraintViolation> constraintViolations = validator.validate(element);
        if(!constraintViolations.isEmpty()){
            throw new DAOException("1234", contraintViolations);
        }
        // it's ok, just persist it
        session.saveOrUpdate(element);
    }
}

And the following exception class:

public class DAOException extends Exception {
private final String errorCode;
private final Set<ConstraintViolation> constraintViolations;

public DAOException(String errorCode, Set<ConstraintViolation> constraintViolations){
    super(String.format("Errorcode %s", errorCode));
    this.errorCode = errorCode;
    this.constraintViolations = constraintViolations;
}
// getters for properties here
}

You could add some annotation information based on what property has not validated from here, but always doing this on the DAO method.

I hope this helped.

Answer 3

You could create a custom annotation to get the behaviour you are looking for and then on validating and using refelection you could extract the value of the annotation. Something like the following:

@Target({ElementType.FIELD})
@Retention(RetentionPolicy.RUNTIME)
public @interface ErrorCode {
    String value();
}

In your bean:

@NotNull
@Length( min = 5, max = 10 )
@ErrorCode("1234")
public String myProperty;

On validating your bean:

Set<ConstraintViolation<MyValidationBean>> constraintViolations = validator.validate(myValidationBean);    
for (ConstraintViolation<MyValidationBean>cv: constraintViolations) {
    ErrorCode errorCode = cv.getRootBeanClass().getField(cv.getPropertyPath().toString()).getAnnotation(ErrorCode.class);
    System.out.println("ErrorCode:" + errorCode.value());
}

Having said that I probably would question the requirements for wanting error codes for these types of messages.