[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-3316) If expression support in the criteria API

[Gail Badner (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-3316?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_30289 ] 

Gail Badner commented on HHH-3316:
----------------------------------

This functionality should already be available, although not with special purpose classes or methods.

The expression can be added as a projection using SQLProjection.

It can be added as a constraint using Expression.sql(...) or Restrictions.sqlRestriction(...).

> If expression support in the criteria API
> -----------------------------------------
>
>                 Key: HHH-3316
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3316
>             Project: Hibernate3
>          Issue Type: Improvement
>          Components: query-criteria
>         Environment: Hibernate 3, MySQL 4.1
>            Reporter: Avlesh Singh
>            Priority: Minor
>
> MySQL supports IF() as one of the Control Flow Structures. I am not too sure if other dialects support an equivalent. 
> This is how it works - 
> SELECT IF(1>2,2,3);
>      -> 3
> To the best of my knowledge, there is no implementation in the Restrictions/Expression class for this control structure. Underneath is what I am talking about this implementation in the Expression class
> public static org.hibernate.criterion.Criterion ifExpression(org.hibernate.criterion.Criterion criterion, java.lang.Object trueValue, java.lang.Object falseValue){}
> for which usage would typically look like this-
> Criteria queryCriteria = session.createCriteria(MyBean.class);
> queryCriteria.add(Expression.ifExpression(Expression.isNull("myProperty"), "myProperty", new Date()));
> the bean definition is underneath -
> class MyBean{
>  private Date myProperty;
> }
> I would love to hear from others on this.

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