Setting a JPA timestamp column to be generated by the database?

Question

In my SQL Server 2000 database, I have a timestamp (in function not in data type) column of type datetime named lastTouched set to (getdate()) as its default value/binding.

I am using the Netbeans 6.5 generated JPA entity classes, and have this in my code

@Basic(optional = false)
@Column(name = "LastTouched")
@Temporal(TemporalType.TIMESTAMP)
private Date lastTouched;

However when I try to put the object into the database I get,

javax.persistence.PersistenceException: org.hibernate.PropertyValueException: not-null property references a null or transient value: com.generic.Stuff.lastTouched

I've tried setting setting the @Basic to (optional = true), but that throws a exception saying the database doesn't allow null values for the timestamp column, which it doesn't by design.

ERROR JDBCExceptionReporter - Cannot insert the value NULL into column 'LastTouched', table 'DatabaseName.dbo.Stuff'; column does not allow nulls. INSERT fails.

I previously got this to work in pure Hibernate, but I have sense switched over to JPA and have no idea how to tell it that this column is suppose to be generated on the database side. Note that I am still using Hiberate as my JPA persistance layer.

Answer 1

private Date lastTouched = new Date();

Answer 2

I fixed the issue by changing the code to

@Basic(optional = false)
@Column(name = "LastTouched", insertable = false, updatable = false)
@Temporal(TemporalType.TIMESTAMP)
private Date lastTouched;

So the timestamp column is ignored when generating SQL inserts. Not sure if this is the best way to go about this. Feedback is welcome.

Answer 3

I realize this is a bit late, but I've had success with annotating a timestamp column with @Column(name="timestamp" columnDefinition="TIMESTAMP DEFAULT CURRENT_TIMESTAMP"). This should also work with CURRENT_DATE and CURRENT_TIME. I'm using JPA/Hibernate with Oracle, so YMMV.

Answer 4

Hello!

I have a question.. hmm this code set automatically the timestamp in the column or I need put it with java code?

Answer 5

Hello,

i use the approach with

@org.hibernate.annotations.Generated(@GenerationTime.INSERT)
@Column(...insertable=false, updatable=false)
private Timestamp created;

which allows the database generation after every insert.

My Problem is now that i only want a database generation if created is not set. The option with @PrePersist seems not work for me because the client and the database are running in different timezones. Especially the database is synchronized with a timeserver and the exact timestamp is crucial.

Thanks in advance Alex