[ZPatterns] Catching mysql exceptions

[John Eikenberry]

We need to be able to catch exceptions raised by the MySQL database backend
in certain cases (eg. duplicate unique indexes). The current method is to
cause a sub-transaction commit and wrap it in the try:except: block. But
these explicit commits are causing other problems with our ZPatterns based
code.  Besides losing the advantages of ZPatterns transaction like
behaviour.

Any suggestions on ways to do this without doing the subcommit? 

Thanks.

-- 

John Eikenberry [jae@kavi.com]
______________________________________________________________
"A society that will trade a little liberty for a little order
 will deserve neither and lose both."
                                          --B. Franklin