[hibernate-issues] [Hibernate-JIRA] Commented: (HV-230) Database Connective or @Unique

[Ken Egervari (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HV-230?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=34048#action_34048 ] 

Ken Egervari commented on HV-230:
---------------------------------

Cool!

Here's an updated version I'm using for 4.0.0rc1:

{code}

public class QueryConstraintValidator implements ConstraintValidator<QueryConstraint,DomainObject> {

	/* Fields */
	private static Logger logger =
		LoggerFactory.getLogger( QueryConstraintValidator.class );

	private String hql;
	private boolean enabled;

	/* Services */
	public void initialize( QueryConstraint queryConstraint ) {
		this.hql = queryConstraint.hql();
		this.enabled = queryConstraint.enabled();
	}

	public boolean isValid( DomainObject domainObject ) {
		return isValid( domainObject, null );
	}

	public boolean isValid( DomainObject domainObject, ConstraintValidatorContext context ) {
		BeanWrapper beanWrapper = new BeanWrapperImpl( domainObject );

		SessionFactory sessionFactory =
			( SessionFactory ) ApplicationContextProvider.getBean( "sessionFactory" );

		if( enabled && sessionFactory != null ) {
			logger.debug( "Enabled - Validating constraint with: " );
			logger.debug( hql );

			Session session = sessionFactory.openSession();
			Transaction tx = session.beginTransaction();
			Query query = session.createQuery(
				HqlParser.removePeriodsFromParameterNames( hql )
			);

			for( String parameterName : HqlParser.getParameterNames( hql ) ) {
				query.setParameter(
					HqlParser.removePeriodsFromParameterName( parameterName ),
					beanWrapper.getPropertyValue( parameterName )
				);
			}

			boolean result = (Long) query.uniqueResult() == 0;

			logger.debug( "isValid is returning: " + result );

			tx.commit();
			session.close();

			return result;
		}

		return true;
	}
}

{code}

And here's the annotation:

{code}

@Constraint( validatedBy = QueryConstraintValidator.class )
@Target( ElementType.TYPE )
@Retention( RetentionPolicy.RUNTIME )
@Documented
public @interface QueryConstraint {

	String hql() default "";

	String message() default "{validator.query}";

	boolean enabled() default true;

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

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

}

{code}

Of course all of this is spring-aware, but I'm sure my suggestions about extending base classes or implementing an interface and what not would replace that ;)

Thanks Hardy!

> Database Connective or @Unique
> ------------------------------
>
>                 Key: HV-230
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HV-230
>             Project: Hibernate Validator
>          Issue Type: New Feature
>          Components: validators
>    Affects Versions: 3.1.0.GA
>            Reporter: Ken Egervari
>            Priority: Critical
>             Fix For: 4.1.0
>
>
> I find a common validation use case is checking to see if a field is unique to all those in the table, such as emails, isbns, usernames, keywords, etc. these fields may not be the primary key, but still need to be unique.
> It would be fantastic if hibernate validator implemented this.
> This is a common problem though because the domain class will need to have access the database. I dunno if there's an easy way to wire in a copy of sessionFactory to make this easy to write.
> Perhaps something like this:
> @Query( "select user from User user where user.emailAddress = :this.emailAddress and user.id != :this.id", message = "That Email is already being used by another user in the system" )
> private String emailAddress;
> Basically the idea is that if @Query returns no results, then the validation constraint is good, and if returns more than 1 result, then it fails. Kind of like simpleJdbcTemplate.queryForMap() does within the Spring testing framework. That method causes the test to fail if no row is returned, because it expects 1 result.
> If it were possible to just say
> @Unique
> private String emailAddress;
> That would be extremely concise and would save people a ton of time. 
> Of course, this requires some interoperability with Hibernate... but I think that's a good thing, no?
> Thanks for taking this into consideration. I'd appreciate an email letting me know how to do this in a clean way in 3.1.0 GA as it is as well if you would. Thank you.

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