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 the @Basic to (optional = true), but that throws an 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 since switched over to JPA and have no idea how to tell it that this column is supposed to be generated on the database side. Note that I am still using Hibernate as my JPA persistence layer.

Answer 1

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.