Automagic updating of timestamps

justinbeck · **Posted:** Thu Dec 01, 2005 1:14 pm

I have an object that I am persisting to a database that has created and modified dates. Those two dates map to columns of MySQL type 'timestamp'.

I don't want to sound lazy, but I'm wondering if there is a way to have Hibernate update those dates for me rather than having to manually do it.

Using insert and update as indicators should make it fairly easy to know whether to update a timestamp or not.

Anyone have any comments or ideas about this?

Thanks!

baliukas · **Posted:** Thu Dec 01, 2005 1:32 pm

CREATE TABLE MY_TABLE (MY_TIME TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP)

Dwightd · **Joined:** Wed Nov 30, 2005 2:41 pm **Posts:** 29

The above takes care of creation timestamp. For modified date, in Oracle we have a trigger:

Code:

CREATE OR REPLACE TRIGGER CATEGORY_R BEFORE UPDATE ON CATEGORY 
  REFERENCING OLD AS OLD NEW AS NEW 
  FOR EACH ROW 
BEGIN
     :new.date_last_mod := SYSDATE ;
END CATEGORY_R ;

I saw a sample mysql trigger, looked similar altho syntax may need fixing.

stijndewitt · **Posted:** Thu Dec 01, 2005 1:57 pm

But won't Hibernate get confused if you use triggers and other database 'magic'? For autoincrement keys you need to specify a generator, is there something like that for this?

Dwightd · **Joined:** Wed Nov 30, 2005 2:41 pm **Posts:** 29

oh, that's probably true. How about doing it in the preSave() and preUpdate() methods? Not exactly automatic, but would eliminate having it in multiple places in application code.