[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-4787) AuditProperty.isNull() doesn't generate "tab.col is null" SQL clause as expected

[Eric Citaire (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-4787?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=35224#action_35224 ] 

Eric Citaire commented on HHH-4787:
-----------------------------------

I found a workaround :

{noformat}
class IsNullCriterion implements AuditCriterion {
	private String propertyName;

	public IsNullCriterion(String propertyName) {
		this.propertyName = propertyName;
	}
	
	public void addToQuery(AuditConfiguration auditCfg,
			String entityName, QueryBuilder qb,
			Parameters parameters) {
		RelationDescription relatedEntity = CriteriaTools.getRelatedEntity(auditCfg, entityName, propertyName);
		if (relatedEntity == null) {
			parameters.addWhere(propertyName, true, " is ", "null", false);
		} else {
			List<QueryParameterData> parametersData = relatedEntity.getIdMapper().mapToQueryParametersFromId(null);
			for (QueryParameterData parameterData : parametersData) {
				parameters.addWhere(parameterData.getQueryParameterName(), true, " is ", "null", false);
			}
		}
	}
}
{noformat}

you can use it by replacing this :

{noformat}
.add(AuditEntity.property("str1").isNotNull())
{noformat}

by this :

{noformat}
.add(new IsNullCriterion("str1"))
{noformat}


> AuditProperty.isNull() doesn't generate "tab.col is null" SQL clause as expected
> --------------------------------------------------------------------------------
>
>                 Key: HHH-4787
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-4787
>             Project: Hibernate Core
>          Issue Type: Bug
>          Components: envers
>    Affects Versions: 3.3.0.GA
>         Environment: Hibernate 3.3.0.GA, Envers 1.2.2, HSQLDB Database
>            Reporter: Eric Citaire
>            Priority: Critical
>
> AuditProperty.isNull() generate a SQL condition like this :
> "tab.col=?"
> where the bind variable is mapped to a null value.
> This doesn't work : most database engines will return false in every case.
> It should use the "is null" test instead :
> "tab.col is null"
> http://en.wikipedia.org/wiki/SQL#Null_and_Three-Valued_Logic_.283VL.29

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