Re: [Modeling-users] Re: How are transaction failures handled?

[Sebastien B. <sbi...@us...>]

Federico Heinz <fh...@vi...> wrote:
> Thanks for the prompt answer! Indeed, this answers my question, but of
> course it prompts another :-)
>=20
> On Thu, 2003-09-25 at 09:46, Sebastien Bigaret wrote:
> >   2. It then opens a transaction in the db, and sends the necessary SQL
> >      statements (INSERT/UPDATE/DELETE) in this transaction. If any error
> >      occurres when these sql statements are executed, the whole
> >      transaction is rolled back.
> >   3. It commits the transaction. Here again, if an error occurs at the
> >      DB-level, the transaction is rolled back.
>=20
> I assume that it also raises an exception at this point. Which exception
> is this, and what information does it contain? (a pointer to the
> relevant code is enough if you don't feel like writing a long answer).

Two different exceptions can be raised

- ValidationException, which you already know,

- GeneralAdaptorException (raised by AdaptorChannel)

- and <embarrassed> hmm, well,... RuntimeError... </embarrassed>

  The relevant code is in ObjectStoreCoordinator's method
  saveChangesInEditingContext(). I *know* the exceptions should be
  better handled --I can still remember when I put the RuntimeError, I
  was finalizing the whole code underneath saveChanges() and didn't want
  to spend some time thinking of exceptions... Then it remained as is.

I'm also quite sure, although I did not check, that
GeneralAdaptorException is swallowed and mutated into a RuntimeError.

  The good news is that I never encountered such errors in any of the
  projects that are still alive. However, if in your environment you
  have, for example, a network that may cause db-connections to be
  randomly dropped, or specialized triggers/validation mechanisms that
  are only coded on the SQL side, then you'll probably need something
  better than a RuntimeError.

This is on the TODO list, obviously. And I'm open to any suggestions to
define the exceptions hierarchy.

-- S=E9bastien.