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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.
395
Here is the SQL you can use to add the column in: ALTER TABLE `table1` ADD `lastUpdated` TIMESTAMP ON UPDATE CURRENT_TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ; This adds a column called 'lastUpdated' with a default value of the current date/time.
MySQL TIMESTAMP() FunctionThe TIMESTAMP() function returns a datetime value based on a date or datetime value. Note: If there are specified two arguments with this function, it first adds the second argument to the first, and then returns a datetime value.
When you persist a new MyEntity, Hibernate will get the current time from the VM and store it as the creation and update timestamp. As you can see in the log output, Hibernate gets a new timestamp for each attribute. The creation and update timestamp will therefore not be the same even if the entity was never updated.
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.
174
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.
55
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