Defaulting logic in entity create method

Question

Hi
As suggested by BC4J I use the create method of my entity object to insert defaulting logic for some attributes. The code looks like this:
protected void create(AttributeList attributeList)
super.create(attributeList);
Number seqNumber = new Number();
SequenceImpl s = new SequenceImpl("REV_SEQ", getDBTransaction());
seqNumber = s.getSequenceNumber();
setRevId(seqNumber);
setCreationDate(SamUtils.getSystemDate());
ApplicationModule am = getDBTransaction().getRootApplicationModule();
if (am instanceof SecuredApplicationModule)
setUsrId(((MyApplicationModule) am).getUsrId());
But executing this code results in an Exception: "JBO-25014: Other User has changed the Row". If I remove the code between the lines above everything works ok.
My questions are:
- Is it ok to use set-Methods in the entity create method? Or should I set my default values to the "attributeList" instead?
- do you think it is a problem to use the ApplicationModule as shown? I should mention that am.getUsrId() simply returns a previously stored variable and does not perform any queries or alike.
Thanks for your help
Frank Brandstetter

Answer 1

It's definitely fine to setAttributes - I've done it myself (but not using "specific" setters).
I haven't used the built-insequences before - this bit of your code looks a bit wasteful in terms of object creation, but that's obviously not your issue....
It looks fine to use an application module in such a way; I coded a "current user id" function on mine too.
I actually suspect the date-attribute, since I (me again!) had some "concurrent user" problems too. The issue was the fact that a Java date is accurate to the millisecond, and the database storage and retrieval wasn't. (I wasn't using Oracle so I'm not sure how it goes there....) A "concurrent user" exception gets thrown when bc4j goes to update an entity and finds that the date-value in the object doesn't match the "rounded" one it retrieves (as a check, just before it does the update - this is the optimistic locking) from the database. [So does the error occur only when you've saved the new entity once, then update it and try to save it again?]
I got around it by setting the millisecond portion of any dates I used to zero (since the "storage" was accurate to a second) - so you might try that. (Did it generically in prepareForDML in my own Entity superclass, I think.)
Otherwise, try setting the attribute, but not in the create method, and seeing if you get the same problem...
HTH
Mike.