Hello all

I reverse engineered my database to produce entity classes for me. For one particular entity, i have a coloumn as follows
@Entity
Person
@javax.persistence.Id @javax.persistence.Column(name = "PID", unique = true, nullable = false, insertable = true, updatable = true) public int getPID(){
..
}

In the database the column is an Identity column

When I try to instantiate an object of type Person, it already seems to have a value of 0 for PID. And when I try to insert the Person object into the database, i get this

Cannot insert explicit value for identity column in table "Person" when IDENTITY_INSERT is set to OFF

Which I can understand because a value of 0 is being given to a column which is meant to be auto generated. My question is how was the value for 0 assigned to PID column.

Any ideas what am I missing?

Thanks
K

Hi,

1.) Since your pid is an int-Property it must have some value, since primitive ints can't be null (only Integers could be).
2.) As pid is an identity-column the value is generated by the database. This should be told to your JPA-Provider by adding an @GeneratedValue-annotation.

Only adding the @GeneratedValue should be sufficient to solve your problem because then hibernate should ignore any value that pid is set to.

Thanks for your reply. I added @GeneratedValue annotation and that seemed to have solved the issue. But I was wondering why wasnt that annotation put in when I reverse engineered that particular entity.

My assumption was hibernate would have enough knowledge to know that a particular column in a table is system generated and it should put the appropriate annotations for it

Thanks again
K

I have tried the same but am getting this error, this is a sample test with the table Sample have id(identity) and value(varchar) columns

Exception in thread "main" org.hibernate.exception.GenericJDBCException: could not insert: [com.refdata.util.Sample]
at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:103)
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:91)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:40)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2158)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2638)
at org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:48)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:250)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:298)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:181)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:107)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:187)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:172)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:535)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:523)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:519)
at com.refdata.util.Test.main(Test.java:30)
Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: A result set was generated for update.
at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(SQLServerException.java:190)
at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement.doExecutePreparedStatement(SQLServerPreparedStatement.java:417)
at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement$PrepStmtExecCmd.doExecute(SQLServerPreparedStatement.java:350)
at com.microsoft.sqlserver.jdbc.TDSCommand.execute(IOBuffer.java:5696)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(SQLServerConnection.java:1715)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeCommand(SQLServerStatement.java:180)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeStatement(SQLServerStatement.java:155)
at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement.executeUpdate(SQLServerPreparedStatement.java:314)
at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:73)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:33)
... 16 more
Java Result: 1

This is my hibernate config file.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.microsoft.sqlserver.jdbc.SQLServerDriver</property>
<property name="hibernate.connection.url">jdbc:sqlserver://localhost;databaseName=test</property>
<property name="hibernate.connection.username">test</property>
<property name="hibernate.connection.password">111</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="show_sql">true</property>
<property name="hibernate.current_session_context_class">thread</property>
<property name="hibernate.connection.pool_size">100</property>
<property name="hibernate.query.factory_class">org.hibernate.hql.classic.ClassicQueryTranslatorFactory</property>
<mapping class="com.refdata.util.ReferenceGroup"></mapping>
<mapping class="com.refdata.util.Sample"></mapping>
</session-factory>
</hibernate-configuration>

Am using sqljdbc4.jar for the driver