Hibernate JPA Sequence (non-Id)

Looking for answers to this problem, I stumbled upon this link

It seems that Hibernate/JPA isn't able to automatically create a value for your non-id-properties. The @GeneratedValue annotation is only used in conjunction with @Id to create auto-numbers.

The @GeneratedValue annotation just tells Hibernate that the database is generating this value itself.

The solution (or work-around) suggested in that forum is to create a separate entity with a generated Id, something like this:

@Entity
public class GeneralSequenceNumber {
  @Id
  @GeneratedValue(...)
  private Long number;
}

@Entity 
public class MyEntity {
  @Id ..
  private Long id;

  @OneToOne(...)
  private GeneralSequnceNumber myVal;
}

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I found that @Column(columnDefinition="serial") works perfect but only for PostgreSQL. For me this was perfect solution, because second entity is "ugly" option.

A call to saveAndFlush on the entity is also necessary, and save won't be enough to populate the value from the DB.

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I know this is a very old question, but it's showed firstly upon the results and jpa has changed a lot since the question.

The right way to do it now is with the @Generated annotation. You can define the sequence, set the default in the column to that sequence and then map the column as:

@Generated(GenerationTime.INSERT)
@Column(name = "column_name", insertable = false)

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Hibernate definitely supports this. From the docs:

"Generated properties are properties which have their values generated by the database. Typically, Hibernate applications needed to refresh objects which contain any properties for which the database was generating values. Marking properties as generated, however, lets the application delegate this responsibility to Hibernate. Essentially, whenever Hibernate issues an SQL INSERT or UPDATE for an entity which has defined generated properties, it immediately issues a select afterwards to retrieve the generated values."

For properties generated on insert only, your property mapping (.hbm.xml) would look like:

<property name="foo" generated="insert"/>

For properties generated on insert and update your property mapping (.hbm.xml) would look like:

<property name="foo" generated="always"/>

Unfortunately, I don't know JPA, so I don't know if this feature is exposed via JPA (I suspect possibly not)

Alternatively, you should be able to exclude the property from inserts and updates, and then "manually" call session.refresh( obj ); after you have inserted/updated it to load the generated value from the database.

This is how you would exclude the property from being used in insert and update statements:

<property name="foo" update="false" insert="false"/>

Again, I don't know if JPA exposes these Hibernate features, but Hibernate does support them.

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I fixed the generation of UUID (or sequences) with Hibernate using @PrePersist annotation:

@PrePersist
public void initializeUUID() {
    if (uuid == null) {
        uuid = UUID.randomUUID().toString();
    }
}

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As a followup here's how I got it to work:

@Override public Long getNextExternalId() {
    BigDecimal seq =
        (BigDecimal)((List)em.createNativeQuery("select col_msd_external_id_seq.nextval from dual").getResultList()).get(0);
    return seq.longValue();
}

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Looks like thread is old, I just wanted to add my solution here(Using AspectJ - AOP in spring).

Solution is to create a custom annotation @InjectSequenceValue as follows.

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface InjectSequenceValue {
    String sequencename();
}

Now you can annotate any field in entity, so that the underlying field (Long/Integer) value will be injected at runtime using the nextvalue of the sequence.

Annotate like this.

//serialNumber will be injected dynamically, with the next value of the serialnum_sequence.
 @InjectSequenceValue(sequencename = "serialnum_sequence") 
  Long serialNumber;

So far we have marked the field we need to inject the sequence value.So we will look how to inject the sequence value to the marked fields, this is done by creating the point cut in AspectJ.

We will trigger the injection just before the save/persist method is being executed.This is done in the below class.

@Aspect
@Configuration
public class AspectDefinition {

    @Autowired
    JdbcTemplate jdbcTemplate;


    //@Before("execution(* org.hibernate.session.save(..))") Use this for Hibernate.(also include session.save())
    @Before("execution(* org.springframework.data.repository.CrudRepository.save(..))") //This is for JPA.
    public void generateSequence(JoinPoint joinPoint){

        Object [] aragumentList=joinPoint.getArgs(); //Getting all arguments of the save
        for (Object arg :aragumentList ) {
            if (arg.getClass().isAnnotationPresent(Entity.class)){ // getting the Entity class

                Field[] fields = arg.getClass().getDeclaredFields();
                for (Field field : fields) {
                    if (field.isAnnotationPresent(InjectSequenceValue.class)) { //getting annotated fields

                        field.setAccessible(true); 
                        try {
                            if (field.get(arg) == null){ // Setting the next value
                                String sequenceName=field.getAnnotation(InjectSequenceValue.class).sequencename();
                                long nextval=getNextValue(sequenceName);
                                System.out.println("Next value :"+nextval); //TODO remove sout.
                                field.set(arg, nextval);
                            }

                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                }
            }

        }
    }

    /**
     * This method fetches the next value from sequence
     * @param sequence
     * @return
     */

    public long getNextValue(String sequence){
        long sequenceNextVal=0L;

        SqlRowSet sqlRowSet= jdbcTemplate.queryForRowSet("SELECT "+sequence+".NEXTVAL as value FROM DUAL");
        while (sqlRowSet.next()){
            sequenceNextVal=sqlRowSet.getLong("value");

        }
        return  sequenceNextVal;
    }
}

Now you can annotate any Entity as below.

@Entity
@Table(name = "T_USER")
public class UserEntity {

    @Id
    @SequenceGenerator(sequenceName = "userid_sequence",name = "this_seq")
    @GeneratedValue(strategy = GenerationType.SEQUENCE,generator = "this_seq")
    Long id;
    String userName;
    String password;

    @InjectSequenceValue(sequencename = "serialnum_sequence") // this will be injected at the time of saving.
    Long serialNumber;

    String name;
}

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If you are using postgresql And i'm using in spring boot 1.5.6

@Column(columnDefinition = "serial")
@Generated(GenerationTime.INSERT)
private Integer orderID;

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Although this is an old thread I want to share my solution and hopefully get some feedback on this. Be warned that I only tested this solution with my local database in some JUnit testcase. So this is not a productive feature so far.

I solved that issue for my by introducing a custom annotation called Sequence with no property. It's just a marker for fields that should be assigned a value from an incremented sequence.

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.FIELD)
public @interface Sequence
{
}

Using this annotation i marked my entities.

public class Area extends BaseEntity implements ClientAware, IssuerAware
{
    @Column(name = "areaNumber", updatable = false)
    @Sequence
    private Integer areaNumber;
....
}

To keep things database independent I introduced an entity called SequenceNumber which holds the sequence current value and the increment size. I chose the className as unique key so each entity class wil get its own sequence.

@Entity
@Table(name = "SequenceNumber", uniqueConstraints = { @UniqueConstraint(columnNames = { "className" }) })
public class SequenceNumber
{
    @Id
    @Column(name = "className", updatable = false)
    private String className;

    @Column(name = "nextValue")
    private Integer nextValue = 1;

    @Column(name = "incrementValue")
    private Integer incrementValue = 10;

    ... some getters and setters ....
}

The last step and the most difficult is a PreInsertListener that handles the sequence number assignment. Note that I used spring as bean container.

@Component
public class SequenceListener implements PreInsertEventListener
{
    private static final long serialVersionUID = 7946581162328559098L;
    private final static Logger log = Logger.getLogger(SequenceListener.class);

    @Autowired
    private SessionFactoryImplementor sessionFactoryImpl;

    private final Map<String, CacheEntry> cache = new HashMap<>();

    @PostConstruct
    public void selfRegister()
    {
        // As you might expect, an EventListenerRegistry is the place with which event listeners are registered
        // It is a service so we look it up using the service registry
        final EventListenerRegistry eventListenerRegistry = sessionFactoryImpl.getServiceRegistry().getService(EventListenerRegistry.class);

        // add the listener to the end of the listener chain
        eventListenerRegistry.appendListeners(EventType.PRE_INSERT, this);
    }

    @Override
    public boolean onPreInsert(PreInsertEvent p_event)
    {
        updateSequenceValue(p_event.getEntity(), p_event.getState(), p_event.getPersister().getPropertyNames());

        return false;
    }

    private void updateSequenceValue(Object p_entity, Object[] p_state, String[] p_propertyNames)
    {
        try
        {
            List<Field> fields = ReflectUtil.getFields(p_entity.getClass(), null, Sequence.class);

            if (!fields.isEmpty())
            {
                if (log.isDebugEnabled())
                {
                    log.debug("Intercepted custom sequence entity.");
                }

                for (Field field : fields)
                {
                    Integer value = getSequenceNumber(p_entity.getClass().getName());

                    field.setAccessible(true);
                    field.set(p_entity, value);
                    setPropertyState(p_state, p_propertyNames, field.getName(), value);

                    if (log.isDebugEnabled())
                    {
                        LogMF.debug(log, "Set {0} property to {1}.", new Object[] { field, value });
                    }
                }
            }
        }
        catch (Exception e)
        {
            log.error("Failed to set sequence property.", e);
        }
    }

    private Integer getSequenceNumber(String p_className)
    {
        synchronized (cache)
        {
            CacheEntry current = cache.get(p_className);

            // not in cache yet => load from database
            if ((current == null) || current.isEmpty())
            {
                boolean insert = false;
                StatelessSession session = sessionFactoryImpl.openStatelessSession();
                session.beginTransaction();

                SequenceNumber sequenceNumber = (SequenceNumber) session.get(SequenceNumber.class, p_className);

                // not in database yet => create new sequence
                if (sequenceNumber == null)
                {
                    sequenceNumber = new SequenceNumber();
                    sequenceNumber.setClassName(p_className);
                    insert = true;
                }

                current = new CacheEntry(sequenceNumber.getNextValue() + sequenceNumber.getIncrementValue(), sequenceNumber.getNextValue());
                cache.put(p_className, current);
                sequenceNumber.setNextValue(sequenceNumber.getNextValue() + sequenceNumber.getIncrementValue());

                if (insert)
                {
                    session.insert(sequenceNumber);
                }
                else
                {
                    session.update(sequenceNumber);
                }
                session.getTransaction().commit();
                session.close();
            }

            return current.next();
        }
    }

    private void setPropertyState(Object[] propertyStates, String[] propertyNames, String propertyName, Object propertyState)
    {
        for (int i = 0; i < propertyNames.length; i++)
        {
            if (propertyName.equals(propertyNames[i]))
            {
                propertyStates[i] = propertyState;
                return;
            }
        }
    }

    private static class CacheEntry
    {
        private int current;
        private final int limit;

        public CacheEntry(final int p_limit, final int p_current)
        {
            current = p_current;
            limit = p_limit;
        }

        public Integer next()
        {
            return current++;
        }

        public boolean isEmpty()
        {
            return current >= limit;
        }
    }
}

As you can see from the above code the listener used one SequenceNumber instance per entity class and reserves a couple of sequence numbers defined by the incrementValue of the SequenceNumber entity. If it runs out of sequence numbers it loads the SequenceNumber entity for the target class and reserves incrementValue values for the next calls. This way I do not need to query the database each time a sequence value is needed. Note the StatelessSession that is being opened for reserving the next set of sequence numbers. You cannot use the same session the target entity is currently persisted since this would lead to a ConcurrentModificationException in the EntityPersister.

Hope this helps someone.

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I run in the same situation like you and I also didn't find any serious answers if it is basically possible to generate non-id propertys with JPA or not.

My solution is to call the sequence with a native JPA query to set the property by hand before persisiting it.

This is not satisfying but it works as a workaround for the moment.

Mario

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I've found this specific note in session 9.1.9 GeneratedValue Annotation from JPA specification: "[43] Portable applications should not use the GeneratedValue annotation on other persistent fields or properties." So, I presume that it is not possible to auto generate value for non primary key values at least using simply JPA.

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You can do exactly what you are asking.

I've found it is possible to adapt Hibernate's IdentifierGenerator implementations by registering them with an Integrator. With this you should be able to use any id sequence generator provided by Hibernate to generate sequences for non-id fields (presumably the non-sequential id generators would work as well).

There are quite a few options for generating ids this way. Check out some of the implementations of IdentifierGenerator, specifically SequenceStyleGenerator and TableGenerator. If you have configured generators using the @GenericGenerator annotation, then the parameters for these classes may be familiar to you. This would also have the advantage of using Hibernate to generate the SQL.

Here is how I got it working:

import org.hibernate.Session;
import org.hibernate.boot.Metadata;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.id.IdentifierGenerator;
import org.hibernate.id.enhanced.TableGenerator;
import org.hibernate.integrator.spi.Integrator;
import org.hibernate.internal.SessionImpl;
import org.hibernate.service.spi.SessionFactoryServiceRegistry;
import org.hibernate.tuple.ValueGenerator;
import org.hibernate.type.LongType;
import java.util.Properties;

public class SequenceIntegrator implements Integrator, ValueGenerator<Long> {
    public static final String TABLE_NAME = "SEQUENCE_TABLE";
    public static final String VALUE_COLUMN_NAME = "NEXT_VAL";
    public static final String SEGMENT_COLUMN_NAME = "SEQUENCE_NAME";
    private static SessionFactoryServiceRegistry serviceRegistry;
    private static Metadata metadata;
    private static IdentifierGenerator defaultGenerator;

    @Override
    public void integrate(Metadata metadata, SessionFactoryImplementor sessionFactoryImplementor, SessionFactoryServiceRegistry sessionFactoryServiceRegistry) {
        //assigning metadata and registry to fields for use in a below example
        SequenceIntegrator.metadata = metadata;
        SequenceIntegrator.serviceRegistry = sessionFactoryServiceRegistry;
        SequenceIntegrator.defaultGenerator = getTableGenerator(metadata, sessionFactoryServiceRegistry, "DEFAULT");
    }

    private TableGenerator getTableGenerator(Metadata metadata, SessionFactoryServiceRegistry sessionFactoryServiceRegistry, String segmentValue) {
        TableGenerator generator = new TableGenerator();
        Properties properties = new Properties();
        properties.setProperty("table_name", TABLE_NAME);
        properties.setProperty("value_column_name", VALUE_COLUMN_NAME);
        properties.setProperty("segment_column_name", SEGMENT_COLUMN_NAME);
        properties.setProperty("segment_value", segmentValue);

        //any type should work if the generator supports it
        generator.configure(LongType.INSTANCE, properties, sessionFactoryServiceRegistry);

        //this should create the table if ddl auto update is enabled and if this function is called inside of the integrate method
        generator.registerExportables(metadata.getDatabase());
        return generator;
    }

    @Override
    public Long generateValue(Session session, Object o) {
        // registering additional generators with getTableGenerator will work here. inserting new sequences can be done dynamically
        // example:
        // TableGenerator classSpecificGenerator = getTableGenerator(metadata, serviceRegistry, o.getClass().getName());
        // return (Long) classSpecificGenerator.generate((SessionImpl)session, o);
        return (Long) defaultGenerator.generate((SessionImpl)session, o);
    }

    @Override
    public void disintegrate(SessionFactoryImplementor sessionFactoryImplementor, SessionFactoryServiceRegistry sessionFactoryServiceRegistry) {

    }
}

You would need to register this class in the META-INF/services directory. Here is what the Hibernate documentation has to say about registering an Integrator:

For the integrator to be automatically used when Hibernate starts up, you will need to add a META-INF/services/org.hibernate.integrator.spi.Integrator file to your jar. The file should contain the fully qualified name of the class implementing the interface.

Because this class implements the ValueGenerator class, it can be used with the @GeneratorType annotation to automatically generate the sequential values. Here is how your class might be configured:

@Entity
@Table(name = "MyTable")
public class MyEntity {

    //...
    @Id //... etc
    public Long getId() {
        return id;
    }

    @GeneratorType(type = SequenceIntegrator.class, when = GenerationTime.INSERT)
    @Column(name = "SEQ_VAL", unique = false, nullable = false, insertable = true, updatable = true)
    public Long getMySequencedValue(){
      return myVal;
    }

}

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I want to provide an alternative next to @Morten Berg's accepted solution, which worked better for me.

This approach allows to define the field with the actually desired Number type - Long in my use case - instead of GeneralSequenceNumber. This can be useful, e.g. for JSON (de-)serialization.

The downside is that it requires a little more database overhead.

First, we need an ActualEntity in which we want to auto-increment generated of type Long:

// ...
@Entity
public class ActualEntity {

    @Id 
    // ...
    Long id;

    @Column(unique = true, updatable = false, nullable = false)
    Long generated;

    // ...

}

Next, we need a helper entity Generated. I placed it package-private next to ActualEntity, to keep it an implementation detail of the package:

@Entity
class Generated {

    @Id
    @GeneratedValue(strategy = SEQUENCE, generator = "seq")
    @SequenceGenerator(name = "seq", initialValue = 1, allocationSize = 1)
    Long id;

}

Finally, we need a place to hook in right before we save the ActualEntity. There, we create and persist aGenerated instance. This then provides a database-sequence generated id of type Long. We make use of this value by writing it to ActualEntity.generated.

In my use case, I implemented this using a Spring Data REST @RepositoryEventHandler, which get's called right before the ActualEntity get's persisted. It should demonstrate the principle:

@Component
@RepositoryEventHandler
public class ActualEntityHandler {

    @Autowired
    EntityManager entityManager;

    @Transactional
    @HandleBeforeCreate
    public void generate(ActualEntity entity) {
        Generated generated = new Generated();

        entityManager.persist(generated);
        entity.setGlobalId(generated.getId());
        entityManager.remove(generated);
    }

}

I didn't test it in a real-life application, so please enjoy with care.

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"I don't want to use a trigger or any other thing other than Hibernate itself to generate the value for my property"

In that case, how about creating an implementation of UserType which generates the required value, and configuring the metadata to use that UserType for persistence of the mySequenceVal property?

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This is not the same as using a sequence. When using a sequence, you are not inserting or updating anything. You are simply retrieving the next sequence value. It looks like hibernate does not support it.

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If you have a column with UNIQUEIDENTIFIER type and default generation needed on insert but column is not PK

@Generated(GenerationTime.INSERT)
@Column(nullable = false , columnDefinition="UNIQUEIDENTIFIER")
private String uuidValue;

In db you will have

CREATE TABLE operation.Table1
(
    Id         INT IDENTITY (1,1)               NOT NULL,
    UuidValue  UNIQUEIDENTIFIER DEFAULT NEWID() NOT NULL)

In this case you will not define generator for a value which you need (It will be automatically thanks to columnDefinition="UNIQUEIDENTIFIER"). The same you can try for other column types

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I have found a workaround for this on MySql databases using @PostConstruct and JdbcTemplate in a Spring application. It may be doable with other databases but the use case that I will present is based on my experience with MySql, as it uses auto_increment.

First, I had tried defining a column as auto_increment using the ColumnDefinition property of the @Column annotation, but it was not working as the column needed to be an key in order to be auto incremental, but apparently the column wouldn't be defined as an index until after it was defined, causing a deadlock.

Here is where I came with the idea of creating the column without the auto_increment definition, and adding it after the database was created. This is possible using the @PostConstruct annotation, which causes a method to be invoked right after the application has initialized the beans, coupled with JdbcTemplate's update method.

The code is as follows:

In My Entity:

@Entity
@Table(name = "MyTable", indexes = { @Index(name = "my_index", columnList = "mySequencedValue") })
public class MyEntity {
    //...
    @Column(columnDefinition = "integer unsigned", nullable = false, updatable = false, insertable = false)
    private Long mySequencedValue;
    //...
}

In a PostConstructComponent class:

@Component
public class PostConstructComponent {
    @Autowired
    private JdbcTemplate jdbcTemplate;

    @PostConstruct
    public void makeMyEntityMySequencedValueAutoIncremental() {
        jdbcTemplate.update("alter table MyTable modify mySequencedValue int unsigned auto_increment");
    }
}

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I was struggling with this today, was able to solve using this

@Generated(GenerationTime.INSERT)
@Column(name = "internal_id", columnDefinition = "serial", updatable = false)
private int internalId;

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I've been in a situation like you (JPA/Hibernate sequence for non @Id field) and I ended up creating a trigger in my db schema that add a unique sequence number on insert. I just never got it to work with JPA/Hibernate

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After spending hours, this neatly helped me to solve my problem:

For Oracle 12c:

ID NUMBER GENERATED as IDENTITY

For H2:

ID BIGINT GENERATED as auto_increment

Also make:

@Column(insertable = false)

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