I think you need to think session bean facade. Have a session bean wrap user
the registration task. The session bean gets the user registration info,
checks the id for uniqueness using a SQL call, generates a "user id taken"
exception if not unique or else creates the user entity bean. 

Rick Hansen

> -----Original Message-----
> From: Jim Archer [mailto:[EMAIL PROTECTED]]
> Sent: Friday, March 02, 2001 2:04 PM
> To: JBoss-User
> Subject: RE: [jBoss-User] Design question - Checking for an existing
> recor d??
> 
> 
> John, thanks for the reply...
> 
> Why do you feel I need a unique key generator? I want the 
> userID to be the 
> key and I want it to be unique, and I want it to be user selected.
> 
> If the user selects an id thats in use, they can pick another 
> and/or the 
> app can suggest one.
> 
> My primary concern is knowing if the user selected ID is 
> already in use. Is 
> there a way I can use a unique key generator for that?
> 
> Thanks...
> 
> Jim
> 
> --On Friday, March 02, 2001 11:55 AM -0800 John Moore 
> <[EMAIL PROTECTED]> wrote:
> 
> >
> >
> > you need a unique key generator.  Check out 
> theserverside.com (patterns
> > section) for discussion on ways to handle it.  JBoss used 
> to come with
> > one but I don't see it any more.
> >
> >
> > -----Original Message-----
> > From: Jim Archer [mailto:[EMAIL PROTECTED]]
> > Sent: Friday, March 02, 2001 11:45 AM
> > To: JBoss-User
> > Subject: [jBoss-User] Design question - Checking for an existing
> > record??
> >
> > Hi All...
> >
> > I have what must be a fairly common problem and I was wondering if
> > someone  could suggest what they think the preferred 
> solution might be.
> >
> > I need to create an EB for a user and I have set the userid up as a
> > primary  jey. Of course, the user ID must be unique. I'm 
> wondering what
> > the best way  to detect that a new user has picked an 
> unavailable user
> > ID.
> >
> > First, I could just try to create the EB and catch a create 
> exception.
> > The  downside to this seems to be that if I get a create exception I
> > don't know  for sure it was created sue to a non-unique key 
> field without
> > looking at  the message text that might vary accross 
> servers. So it seems
> > that I can  only know that there was some problem.
> >
> > The next option is to use the finder for primary key and 
> see if I get a
> > record back. This would answer the question but seems like 
> extra overhead
> > to introduce. Also, it would result in a FinderException 
> when the userID
> > is  unique and I don't know if that will roll back the 
> transaction I'm in
> > or  not. Of course, I have to check for existance and add 
> the new one in
> > the  same transaction.
> >
> > Is there a third option? I would appreciate any suggestions!
> >
> > Thanks lots!
> >
> > Jim
> >
> > ********************************************
> > I shall be telling this with a sigh
> > Somewhere ages and ages hence:
> > Two roads diverged in a wood, and I -
> > I took the one less traveled by,
> > And that has made all the difference.
> >
> > - Robert Frost, 1916
> >
> >
> > --
> > --------------------------------------------------------------
> > To subscribe:        [EMAIL PROTECTED]
> > To unsubscribe:      [EMAIL PROTECTED]
> 
> 
> 
> ********************************************
> I shall be telling this with a sigh
> Somewhere ages and ages hence:
> Two roads diverged in a wood, and I -
> I took the one less traveled by,
> And that has made all the difference.
> 
> - Robert Frost, 1916
> 
> 
> 
> --
> --------------------------------------------------------------
> To subscribe:        [EMAIL PROTECTED]
> To unsubscribe:      [EMAIL PROTECTED]
> 


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