I have trouble adding an index to a column of a table which is part of a many-to-many property mapping. The following example causes a NullPointerException when generating the DDL (the exception can be seen at the end of my post):
Code:
@Entity @Table(name="usr")
public class User implements Serializable
{
@Id @GeneratedValue(strategy=GenerationType.AUTO)
public Integer id;
@ManyToMany(targetEntity=Target.class, cascade={})
@Index(name="fkey_usr_target", columnNames="usr_id")
@JoinTable(name="usr_target",
joinColumns=@JoinColumn(name="usr_id"),
inverseJoinColumns=@JoinColumn(name="target_id"))
public Collection<Target> targets;
}
@Entity @Table(name="target")
public class Target implements Serializable
{
@Id @GeneratedValue(strategy=GenerationType.AUTO)
public Integer id;
@Basic
public String myValue;
}
It is quite possible that I use the wrong annotation for the index, but I cannot seem to find sample code or postings that illustrates how to do it, so this is my best guess. Is it the correct way to add an index?
NullPointerException thrown when an @Index annotation is used with a @ManyToMany:
Code:
java.lang.NullPointerException
at org.hibernate.cfg.AnnotationBinder.processElementAnnotations(AnnotationBinder.java:1594)
at org.hibernate.cfg.AnnotationBinder.bindClass(AnnotationBinder.java:733)
at org.hibernate.cfg.AnnotationConfiguration.processArtifactsOfType(AnnotationConfiguration.java:498)
at org.hibernate.cfg.AnnotationConfiguration.secondPassCompile(AnnotationConfiguration.java:277)
at org.hibernate.cfg.Configuration.buildMappings(Configuration.java:1115)
at org.hibernate.tool.ant.ConfigurationTask.getConfiguration(ConfigurationTask.java:56)
at org.hibernate.tool.ant.HibernateToolTask.getConfiguration(HibernateToolTask.java:299)
at org.hibernate.tool.ant.Hbm2DDLExporterTask.execute(Hbm2DDLExporterTask.java:45)
at org.hibernate.tool.ant.HibernateToolTask.execute(HibernateToolTask.java:183)
at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:288)
at sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:105)
at org.apache.tools.ant.Task.perform(Task.java:348)
at org.apache.tools.ant.Target.execute(Target.java:357)
at org.apache.tools.ant.Target.performTasks(Target.java:385)
at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1329)
at org.apache.tools.ant.Project.executeTarget(Project.java:1298)
at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
at org.apache.tools.ant.Project.executeTargets(Project.java:1181)
at org.apache.tools.ant.Main.runBuild(Main.java:698)
at org.apache.tools.ant.Main.startAnt(Main.java:199)
at org.apache.tools.ant.launch.Launcher.run(Launcher.java:257)
at org.apache.tools.ant.launch.Launcher.main(Launcher.java:104)
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