Hibernate : How override an attribute from mapped super class

Question

The generic entity, super class:

@MappedSuperclass
public abstract class GenericEntity {
    private Integer id;
    public Integer getId() {return id;}
    public void setId(Integer id) {this.id = id;}
}

The pojo:

@Entity
@Table(name = "POJO_ONE")
@SequenceGenerator(name = "HB_SEQ_POJO_ONE", sequenceName = "SEQ_POJO_ONE", allocationSize = 1)
public class PojoOne extends GenericEntity {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "HB_SEQ_POJO_ONE")
    @Column(name = "ID")
    @AttributeOverride(name = "id", column = @Column(name = "ID"))
    private Integer id;

    @Override
    public Integer getId() {return id;}
}

I try to use thoses annotations : @AttributeOverride, @Id, ... but It doesn't work. Can you help me? I want to override the attribute "id" to specify another column name and a sequence by pojo/table. What is the best way to do that?

opensource.atlassian.com/projects/hibernate/browse/HHH-4380

axtavt
– axtavt

2011-03-10 10:22:28 +00:00
Commented Mar 10, 2011 at 10:22 — axtavt
– axtavt, Commented Mar 10, 2011 at 10:22

Adeel Ansari · Accepted Answer · 2020-11-02 03:38:02Z

36

Try this, instead

@MappedSuperclass
public abstract class GenericEntity {
    protected Integer id;
    ...

    public Integer getId() {return id;}
    public void setId(Integer id) {this.id = id;}
}


@Entity
@Table(name = "POJO_ONE")
@SequenceGenerator(name = "HB_SEQ_POJO_ONE", sequenceName = "SEQ_POJO_ONE", allocationSize = 1)
@AttributeOverride(name = "id", column = @Column(name = "ID"))
public class PojoOne extends GenericEntity {
    // we should not define id here again
    ...

    @Override
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "HB_SEQ_POJO_ONE")
    public Integer getId() {return id;}
}

edited Nov 2, 2020 at 3:38

answered Mar 10, 2011 at 10:05

Adeel Ansari

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10 Comments

BasicCoder Over a year ago

With this solution, when I try to save, I have this exception : org.hibernate.id.IdentifierGenerationException: ids for this class must be manually assigned before calling save()

Adeel Ansari Over a year ago

@user616564: Then just take the @GeneratedValue annotation to the MappedSuperClass, but then subclasses wouldn't be able to give their own implementation. If that is fine with you.

sfitts Over a year ago

The answer here -- stackoverflow.com/questions/8589928/… provides what I consider to be a slightly better approach since it duplicates less code.

user2360507 Over a year ago

Wouldn't overriding the getter, getId(), not be possible? id is private in the GenericEntity, so the child has no access to the property.

Adeel Ansari Over a year ago

@user2360507: Fixed. Thanks. That's there in the original post, and I copied that here, I think.

|

Thomas · Accepted Answer · 2011-03-10 13:30:49Z

4

Why don't you annotate the id of GenericEntity with @Id? You also should not redefine id but put the @AttributeOverride(name = "id", column = @Column(name = "ID")) on the class rather than a field.

Edit:

We're using this in our base class (package.OurTableGenerator is our own implementation):

@GeneratedValue ( generator = "ourTableGenerator", strategy = GenerationType.TABLE )
@GenericGenerator ( name = "ourTableGenerator", strategy = "package.OurTableGenerator",
  parameters = { @Parameter ( name = OurTableGenerator.TABLE_PARAM, value = "t_sequence" ),
                 @Parameter ( name = OurTableGenerator.SEGMENT_COLUMN_PARAM, value = "c_entity" ),
                 @Parameter ( name = OurTableGenerator.VALUE_COLUMN_PARAM, value = "c_nextHi" ),
                 @Parameter ( name = OurTableGenerator.INCREMENT_SIZE_COLUMN_PARAM, value = "c_blocksize" ) } )
@Id
@Column(name = "c_uid")
private Long uid;

This let's us specify a differenc block size and sequence per entity/table.

For your own table generator you could subclass org.hibernate.id.TableGenerator.

edited Mar 10, 2011 at 13:30

answered Mar 10, 2011 at 10:01

Thomas

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3 Comments

BasicCoder Over a year ago

And how can I specify a sequence by table/entity for the id?

Kiran Kumar Over a year ago

It will be great if you can post the source code of the class OurTableGenerator

Thomas Over a year ago

@KiranKumar the exact code depends on the Hibernate version but basically it's a subclass of org.hibernate.id.enhanced.TableGenerator and a few overridden methods, especially configure(...), generate(...) as well as the methods that provide the SQL strings.

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