Issues with inheritance
I have encountered issues with entity enheritance. Here is my case:
I basically followed the instructions in the tutorial when i coded.
First I have a base entity class called Message like this:
package ejb3.language.system;
import java.io.Serializable;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.DiscriminatorType;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE, discriminatorType = DiscriminatorType.STRING)
@DiscriminatorColumn(name = "TYPE", columnDefinition="VARCHAR(255)", nullable = true)
public class Message implements Serializable
{
private static final long serialVersionUID = 1L;
private MessagePK pk;
private String value;
@EmbeddedId
public MessagePK getPk() {
return pk;
}
public void setPk(MessagePK pk) {
this.pk = pk;
}
@Column(columnDefinition="text")
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
}
This entity bean has a composite primary key class like this:
package ejb3.language.system;
import java.io.Serializable;
import javax.persistence.AccessType;
import javax.persistence.Embeddable;
@Embeddable(access = AccessType.PROPERTY)
public class MessagePK implements Serializable
{
private static final long serialVersionUID = 1L;
private String object_member;
private int object_id;
private String url;
public int getObject_id() {
return object_id;
}
public void setObject_id(int object_id) {
this.object_id = object_id;
}
public String getObject_member() {
return object_member;
}
public void setObject_member(String object_member) {
this.object_member = object_member;
}
public String getUrl() {
return url;
}
public void setUrl(String url) {
this.url = url;
}
}
I then have some classes that inherits from the base class in order to achieve different "types" to be stored within the same table. Like this one:
package ejb3.language.system;
import java.io.Serializable;
import javax.persistence.Entity;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
import com.lightminds.ppdb.ejb3.country.Country;
@Table(name="Message")
@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE, discriminatorType = DiscriminatorType.STRING, discriminatorValue = "Country")
public class Message_CountryView extends Message implements Serializable
{
private static final long serialVersionUID = 1L;
private Country country;
@ManyToOne
@JoinColumn(name = "object_id", insertable=false, updatable=false)
public Country getCountry()
{
return country;
}
public void setCountry(Country country)
{
this.country = country;
}
}
All fine. And all deployes well on latest RC2 release of EJB3. I can successfully add both Messages and Country and other into the table with the normal persist stuff. However when I try to fetch a specific row in the database represented by one of the inherited clasess I get errors.
First If I try something like this:
MessagePK pk = new MessagePK();
pk.setObject_id(1);
pk.setObject_member("test2");
pk.setUrl("www.mysite.org");
Message_CountryView message = MyEntityManager.find(Message_CountryView.class, pk);
I get the following error:
org.hibernate.exception.GenericJDBCException: could not load an entity: [ejb3.language.system.Message_CountryView#component[url,object_id,object_member]{object_id=1, url=www.mysite.org, object_member=test2}]
.......
Caused by: java.sql.SQLException: Invalid value for getInt() - 'test2' in column 3
and if I manually create a query like this:
Message_CountryView message = (Message_CountryView)MyEntityManager.createQuery("SELECT mcv FROM Message_CountryView mcv WHERE mcv.pk = :key").setParameter("key", pk).getSingleResult();
I get a similar error:
org.hibernate.exception.DataException: could not execute query
.........
Caused by: java.sql.SQLException: Operand should contain 3 column(s)
Also note that if I create an entry with the type of the base class. I.e Message - both the above "finds" works if the row returned is of the base class type, but If I query for an entry that is represented by one of the inherited classes I get the above errors even if I query for the base class (Message message = MyEntityManager.find(Message.class, pk);)
Thanks in advance
