[Catalyst] ->model-> return values?

Matt S Trout dbix-class at trout.me.uk
Mon Sep 25 17:17:18 CEST 2006

Roderick A. Anderson wrote:
> Matt S Trout wrote:
>> Roderick A. Anderson wrote:
>>> I'm 'looked-out'  Been searching and reading for the last two hours with 
>>> no good results.
>>> A pointer/suggestion/clue-stick would be appreciated.
>>> Do I need to wrap a
>>> 	$c->model( 'TheModel' )->update( ... )
>>> or
>>> 	$c->model( 'TheModel' )->delete( ... )
>>> in an eval block to check for success or failure or ( hope, hope, hope ) 
>>> can I just test the return value?
>> Assuming you're using DBIx::Class, it depens what you mean by success or 
>> failure - do you mean success as in "updated/deleted something" or as in "ran 
>> the appropriate query successfully" ?
> Sorry it seemed so clear in my mind.  :-)
> Yes using DBIx::Class.
> If the update or delete succeeded in updating or deleting; not just running.
> So if an update query should fail because NULL got passed to a NOT NULL 
> field, a letter got into an INT field, etc. or an delete fails because 
> the key doesn't exist.  I'm looking to determine if the update or delete 
> succeeds then do one thing if it fails then another.

If the DB throws an error on the statement you'll get an exception.

If not I -think- you'll get number of rows affected, but not 100% sure without 
looking. If you don't, prod the dbic list because I suspect that would count 
as a bug.

Note that if you find eval unpleasant, you're gonna run into other problems - 
most of Catalyst+DBIC stuff does exception-on-fail, in fact I'd say a majority 
of OO perl stuff does. There are modules that provide try/catch semantics if 
you prefer that way (Error.pm springs to mind), personally I just learned to 
love eval and $@ :)

      Matt S Trout       Offering custom development, consultancy and support
   Technical Director    contracts for Catalyst, DBIx::Class and BAST. Contact
Shadowcat Systems Ltd.  mst (at) shadowcatsystems.co.uk for more information

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