EmbeddedId and GeneratedValue

[nholbrook]

I have a composite key with 2 fields. 1 field is an auto-incrementing field, the other is a foreign key. I've been trying to put @GeneratedValue annotation on the auto-incrementing field, but can't seem to get it to work properly. Is this supported? I assumed thats why it was broken out of the @ID annotation so that it could be used on any field.

This is a major setback to our development if this isn't supported.

----- Customer Class -----
@EmbeddedId
@AttributeOverrides( {
@AttributeOverride(name = "customerId", column = @Column(name = "customer_id", unique = false, nullable = false, insertable = true, updatable = true)),
@AttributeOverride(name = "carrierId", column = @Column(name = "carrier_id", unique = false, nullable = false, insertable = true, updatable = true))})
public CustomerId getId()
{
return this.id;
}

------- CustomerId class ---------------

@GeneratedValue(strategy= GenerationType.AUTO)
@Column(name = "customer_id", unique = true, nullable = false, insertable = true, updatable = true)
public Integer getCustomerId()
{
return this.customerId;
}

@Column(name = "carrier_id", unique = false, nullable = false, insertable = true, updatable = true)
public Integer getCarrierId()
{
return this.carrierId;
}

-------------------------------------------

Thanks

Nic

[bill.burke]

id generation is not supported/required by the specification for composite keys.

I do suggest you log a feature request and bug on www.hibernate.org

feature request: to allow generated values for composite id properties
bug report: to get a clearer error message.

[nholbrook]

Done. Thanks.

http://opensource2.atlassian.com/projects/hibernate/browse/ANN-268

[nholbrook]

Well, I did some digging around and came up with an interim solution that seems to work pretty well. I have multiple databases so I picked my common module to manage autogenerated id's for compount primary keys. The first is the entity object I generated in the database. The second is the IDGenerator class for my composite-id entity objects. The third is the basic logic behind the generator. Anyway, I just thought I'd post this since there isn't a lot of information out there on GenericGenerators. If I have something bad in here, let me know...

Thanks

Nic

------------------------------------- Entity on the table that manages the id's -----------------------------

@Entity
@Table(name="sec_uuid")
public class SecUUID implements java.io.Serializable
{
private String entity;
private Long value;

public SecUUID()
{

}

public SecUUID(String entity, Long value)
{
this.entity = entity;
this.value = value;
}

@Id
@Column(name="entity", unique = true, nullable = false, insertable = true, updatable = true, length = 45)
public String getEntity()
{
return entity;
}
public void setEntity(String entity)
{
this.entity = entity;
}

@Column(name="value", unique = false, nullable = true, insertable = true, updatable = true)
public Long getValue()
{
return value;
}
public void setValue(Long value)
{
this.value = value;
}
}

--------------------------------------- Id generator class -------------------------------------------

/**
*
* The following is an example annotation to be used on the class declaration of the entity.
* Column name(In this case customerId) is the name of the property inside the embedded id that needs to be auto-incremented.
* The column also needs to be of type Long.
* @GenericGenerator(name = "KeyGenerator", strategy = "EmbeddedIDGenerator",
* parameters = {
* @Parameter (name=EmbeddedIDGenerator.COLUMN_NAME, value="customerId")
* }
* )
*
*
* The following is the tag that needs to put on the Id field of the entity. This field must
* be an embedded id and the name must be id.
* @GeneratedValue(generator = "KeyGenerator")
*/
public class EmbeddedIDGenerator
implements IdentifierGenerator, Configurable
{
private static final Log log = LogFactory.getLog(EmbeddedIDGenerator.class);
public static final String COLUMN_NAME = "uuid_column";

private String entityName;
private String columnName;

public Serializable generate(SessionImplementor sessionImplementor, Object arg1)
throws HibernateException
{
log.debug("Generating id for entity " + entityName);

Object entity = arg1;

try
{
log.debug("Working on entity " + entity.getClass().getName());
Serializable key = (Serializable)PropertyUtils.getProperty(entity, "id");
log.debug("I have key for entity " + key.getClass().getName());
log.debug("Looking up the next uuid for key " + key);

// This is where you will make a call or execute sql to get your next id.
Long id = ProxyFactory.getProxy().getNextUUID(entityName);


log.debug("Setting the value " + id + " on property " + columnName);
PropertyUtils.setProperty(key, columnName, id);

return key;
}
catch (IllegalAccessException e)
{
log.error(e);
throw new TessRuntimeException("There was an error generating the id for " + entityName);
}
catch (InvocationTargetException e)
{
log.error(e);
throw new TessRuntimeException("There was an error generating the id for " + entityName + ". Key must have a setter for column " + columnName);
}
catch (NoSuchMethodException e)
{
log.error(e);
throw new TessRuntimeException("There was an error generating the id for " + entityName + ". Entity must have a getId() method.");
}
}

public void configure(Type type, Properties properties, Dialect dialect)
throws MappingException
{
entityName = properties.getProperty(ENTITY_NAME);
columnName = properties.getProperty(COLUMN_NAME);
}
}



---------------------------------------------------------- UUID Generation Logic --------------

public Long getNextUUID(String entityName)
{

String QUERY = "from SecUUID as uuid where uuid.entity = :entityName";
SecUUID uuid;
try
{
log.debug("Looking up entity " + entityName);
uuid = (SecUUID)pm.getEntityManager().createQuery(QUERY).setParameter("entityName", entityName).getSingleResult();
uuid.setValue(uuid.getValue() + 1L);
log.debug("Incrementing the uuid by 1");
log.debug("updating value to " + uuid.getValue());
pm.getEntityManager().flush();
return uuid.getValue();
}
catch (NoResultException e)
{
log.debug("No uuid fond for entity " + entityName);
pm.insert(new SecUUID(entityName, 1L));
log.debug("Inserted entry for " + entityName);
return 1L;
}
}

-------------------------------- Example Entity -------------------------------------

@Entity
@GenericGenerator(name = "KeyGenerator", strategy = "com.bla.util.EmbeddedIDGenerator",
parameters = {
@Parameter (name=EmbeddedIDGenerator.COLUMN_NAME, value="customerId")
})
@Table(name = "customer", catalog = "tescsm", uniqueConstraints = {})
public class Customer
{
@EmbeddedId
@GeneratedValue(generator = "KeyGenerator")
@AttributeOverrides( {
@AttributeOverride(name = "customerId", column = @Column(name = "customer_id", unique = false, nullable = false, insertable = true, updatable = true)),
@AttributeOverride(name = "carrierId", column = @Column(name = "carrier_id", unique = false, nullable = false, insertable = true, updatable = true))})
public CustomerId getId()
{
return this.id;
}
}

-------------------------------------- Embeddable Id ------------------------------

@Embeddable
public class CarrierCustomerId
implements java.io.Serializable
{

// Fields

private Long customerId;
private Integer carrierId;

// Constructors

/** default constructor */
public CarrierCustomerId()
{
}

/** full constructor */
public CarrierCustomerId(Long customerId, Integer carrierId)
{
this.customerId = customerId;
this.carrierId = carrierId;
}

// Property accessors

@Column(name = "customer_id", unique = true, nullable = false, insertable = true, updatable = true)
@GeneratedValue
public Long getCustomerId()
{
return this.customerId;
}

public void setCustomerId(Long customerId)
{
this.customerId = customerId;
}

@Column(name = "carrier_id", unique = false, nullable = false, insertable = true, updatable = true)
public Integer getCarrierId()
{
return this.carrierId;
}

public void setCarrierId(Integer carrierId)
{
this.carrierId = carrierId;
}
}

[squishy]

I think it's surprising that there's so little about composite primary keys with auto generated values yet..

Isn't it also possible that, evertime you add a new entry to the database you do a query like (Role is the entity i tried with)

"SELECT MAX(r.roleId) + 1 FROM Role r"

and take it as the ID?
I don't like it this way, because the code isnt in the entity itself, but i prefer it over creating a whole new table for primary keys, which doesn't appear very clean to me...

Isn't there a proper implementation for @GeneratedValue by the container/hibernate yet??

[epbernard]

your solution can be very inefficient and conceptually does not work. you need to think about concurrent transactions.

[squishy]

i thoguht so. do you have an idea for working solution? i'd be very thankful :)

[epbernard]

the one provided by the spec :-)
TABLE is very efficient, clean and respectful of your Tx concurrency.

[squishy]

uh, there is one? tried several things with @GeneratedValue Annotation, but the only id i got generated was 0 :o

[squishy]

(the class has @IdClass with appropriate PK-class)

@Id @GeneratedValue(strategy=GenerationType.TABLE)
 public int getUserId() {
 return userId;
 }

leads to a
java.sql.BatchUpdateException: failed batch

on the 2nd insert into the database.
1 Entity is wrote to the database, its Id is 0.

is this how it is supposed to be? :o

[epbernard]

check the test suites this definitely works.
If you don't use DDL generation, you'll have to create the increment table yourself before running the app

[squishy]

apparently hibernate does not create an entry in HIBERNATE_SEQUENCES for my Bean with the PK class, but for the same one without pk class..
Uhm.. can you give me a hint on how to find a test suit that tests this.. ? (no clue of them test suits :o)

[squishy]

I tested the same beans with new Jboss 4.0.4CR2 + EJB3CR6, the only thing that's different is that i get no errors, because the row with id 0 is simply overridden by each new entity that is added to the database. (no errors there!)
No HIBERNATE_SEQUENCES table is created either.

Could you be so kind to show me a working example? (or point me to where i find one :)
im totally lost here..

[squishy]

just realized the overiding happens because i used manager.merge instead of manager.persist .
Doesn't solve my problem though..

[squishy]

Entity Class:

package ejbframe.entity;

import javax.persistence.*;

@Entity
@IdClass(UserPK.class)
@Table(name = "users")
public class User {

 private int userId;
 private String name;
 private String password;

 @Id @GeneratedValue(strategy = GenerationType.TABLE)
 public int getUserId() {
 return userId;
 }
 public void setUserId(int userId) {
 this.userId = userId;
 }

 public String getName() {
 return name;
 }
 public void setName(String name) {
 this.name = name;
 }

 public String getPassword() {
 return password;
 }
 public void setPassword(String password) {
 this.password = password;
 }
}

PK class:

package ejbframe.entity;

import java.io.Serializable;

public class UserPK implements Serializable {

 private int userId;

 public UserPK () {}


 public int getUserId() {
 return userId;
 }

 public void setUserId(int userId) {
 this.userId = userId;
 }
}

no ids are generated, no tables for id generation created.
If i comment out the @IdClass it works perfectly.
help please :(