JPA increase the value of a column by one

Question

I am trying to implement a DAO that increases the value of the "version" column automatically. The version is not a primay key. The problem is that I tried the "@GeneratedValue" value before, but it didnt work and sql was giving a message this is only allowed for a primarykey columns, so I had to use the lastUpdate value and increase it one value, but this doesn't work and it keeps passing 1 for the insert value.

here is my code :

@Repository
public class VersionDAO {

    @PersistenceContext
    private EntityManager em;

    public void create(Version version) {
        Version lastUpdate = (Version) em.createQuery("SELECT c FROM Version c ORDER BY c.uploadedtimestamp DESC")//
        .setMaxResults(1).getResultList();
        int ver = lastUpdate.getVersion() + 1;
        version.setVersion(ver);

        em.persist(version);
    }

    public void delete(Version version) {
        em.remove(version);
    }
}

@Entity
@Table(name = "version")
public class Version implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Integer id;


    @Column(name = "version")   
    private Integer version;

    @Column(name="uploadedtimestamp")
    @Temporal(TemporalType.TIMESTAMP)
    private Date uploadedtimestamp = new Date();        

    public Integer getId() {
        return id;
    }

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

    public Integer getVersion() {
        return version;
    }

    public void setVersion(Integer version) {
        this.version = version;
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == null) {
            return false;
        }
        if (obj == this) {
            return true;
        }
        if (obj.getClass() != getClass()) {
            return false;
        }
        Version cdi = (Version) obj;
        return new EqualsBuilder().append(getId(), cdi.getId()).isEquals();
    }

    @Override
    public int hashCode() {
        return new HashCodeBuilder(17, 37).append(getId()).toHashCode();
    }

    public Date getUploadedtimestamp() {
        return uploadedtimestamp;
    }

    public void setUploadedtimestamp(Date uploadedtimestamp) {
        this.uploadedtimestamp = uploadedtimestamp;
    }
}

I think it is not clear what you want. Is it somethig like [http://stackoverflow.com/questions/2572566/java-jpa-version-annotation]. A version when updating an entity? — Jens, Jun 10 '14 at 13:16
no the version name is for something else. I just want to add its value by one, everytime there is a new insert — user261002, Jun 10 '14 at 13:18
Are you trying to update a field called version or you are trying to create a new object with an incremented version — fmucar, Jun 10 '14 at 13:18
@user261002 which DBMS are you using? Mysql, SQL Server, what else? — davioooh, Jun 10 '14 at 13:37

score 3 · Accepted Answer · edited May 23 '17 at 12:04

3

In JPA 2.0 there is the @Version annotation.

You just need to add the annotation to the field you want to be your version field, like that:

@Entity
public class MyEntity implements Serializable {    

    @Id
    @GeneratedValue
    private Long id;

    private String name;

    @Version
    private Long version;

    //...
}

Take a look at: Java - JPA - @Version annotation

edited May 23 '17 at 12:04

Community

1
1

answered Apr 30 '15 at 22:02

Panthro

3,247
2
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score 1 · Answer 2 · answered Jun 10 '14 at 13:30

try to select max version, and update the value + 1.

public void incrementVersion() {
        Version lastUpdate = (Version) em.createQuery("SELECT max (c.version) FROM X c")          .setMaxResults(1).getResultList();
        int ver = lastUpdate.getVersion() + 1;
        lastUpdate.setVersion(ver);

        em.persist(lastUpdate);
    }

davioooh · Answer 3 · 2014-06-10T15:28:10.190

0

I think you shouldn't handle this via JPA. You can create a trigger for your table to automatically increase "version" value every time a row is updated.

If you're using MySQL for example:

CREATE TRIGGER version_trigger BEFORE UPDATE ON `your_table`
FOR EACH ROW
SET NEW.version = (OLD.version + 1)

edited Jun 10 '14 at 15:28

answered Jun 10 '14 at 13:39

davioooh

23,742
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This is not a valid answer as it does not use JPA as the OP asked and kinda breaks the concept of jpa database agnosticism – Panthro Apr 30 '15 at 21:58

JPA increase the value of a column by one

3 Answers3