On Fri, 2 Mar 2001, John Moore 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.
>
No, I don't think a unique key generator is the answer here, since the
user needs to be able to elect a user ID, then that should be checked.
Why not either try a lookup on that user name, with ejbFindByPrimaryKey,
and catch NoSuchEntityException, or put a SQL query in a session bean to
check if the user name exists?
Tom
> -----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
>
>
>
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