[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-5301) Add support for parametrizing TYPE(e) expressions
[
http://opensource.atlassian.com/projects/hibernate/browse/HHH-5301?page=c...
]
Ted Young commented on HHH-5301:
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For what it is worth, you can at least get access to the discriminator by exposing it as a
private read-only property. I wrote up an example here:
http://tedyoung.me/2011/08/08/jpa-and-hibernate-problems-with-polymorphic...
This was particularly important for me where I had to group by and order by type. It
isn't perfect, though. Note the issues described at the end of the article. But, it
works for now.
Add support for parametrizing TYPE(e) expressions
-------------------------------------------------
Key: HHH-5301
URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5301
Project: Hibernate Core
Issue Type: Bug
Components: query-hql
Affects Versions: 3.5.2
Environment: Hibernate 3.5.2, Java 6.0.20
Reporter: Luis Fernando Planella Gonzalez
Assignee: Gail Badner
Attachments: query-test-type-expression.patch
Support parameters for JPA 2's TYPE(alias) function.
Test classes:
@Entity
@DiscriminatorColumn(name="subclass")
@Table(name="xs")
public abstract class XBase {
@Id
private Integer id;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
}
@Entity
@DiscriminatorValue("x1")
public class X1 extends XBase {
@Basic
private String x1;
public String getX1() {
return x1;
}
public void setX1(String x1) {
this.x1 = x1;
}
}
@Entity
@DiscriminatorValue("x2")
public class X2 extends XBase {
@Basic
private String x2;
public String getX2() {
return x2;
}
public void setX2(String x2) {
this.x2 = x2;
}
}
Running the following query works: "select x from XBase x where type(x) = X1"
However, the following one: "select x from XBase x where type(x) = :t" yelds
Exception in thread "main" java.lang.UnsupportedOperationException: At the
moment this type is not the one actually used to map the discriminator.
at
org.hibernate.persister.entity.DiscriminatorType.nullSafeSet(DiscriminatorType.java:111)
at
org.hibernate.param.NamedParameterSpecification.bind(NamedParameterSpecification.java:67)
at org.hibernate.loader.hql.QueryLoader.bindParameterValues(QueryLoader.java:567)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1612)
at org.hibernate.loader.Loader.doQuery(Loader.java:717)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:270)
at org.hibernate.loader.Loader.doList(Loader.java:2294)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2172)
at org.hibernate.loader.Loader.list(Loader.java:2167)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:448)
at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:363)
at org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1258)
at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102)
at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:241)
at test.Main.main(Main.java:28)
JPA 2's spec explicitly shows querying by type using parameters in section 4.6.17.4.
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