Cool, I might have suggested using versioning if all you are trying to do is to track changes.
On Friday, November 9, 2012 3:38:28 PM UTC-7, Jim S wrote: > > Just reporting back. The _before_update is working perfectly for me. > > -Jim > > > On Fri, Nov 9, 2012 at 3:45 PM, Jim Steil <ato....@gmail.com <javascript:> > > wrote: > >> Thanks Niphlid, I was going to ask about the db.commit issue before but >> forgot. I'm going to give the _before_update callback a try and see how >> well that works for me. >> >> Thanks for all the responses, I truly appreciate it. >> >> -Jim >> >> On Fri, Nov 9, 2012 at 3:32 PM, Niphlod <nip...@gmail.com >> <javascript:>>wrote: >> >>> simple "scientific" thoughts. >>> It's like databases triggers. Db triggers apply to the "onupdate" event, >>> i.e. they let you use a set of just updated fields AND the fields that are >>> going to be updated. >>> Web2py has to intercept the update before or after, because databases >>> (the python dbapi in general) don't expose that functionality. I rely on >>> database triggers most of the times (as soon as I have access to the >>> underlying database), but that's just because for simple things I'm faster >>> on coding database triggers than python functions. >>> >>> However, with after_update, you can't "scientific-ly" know the values >>> the rows had before the update, because the update has "already happened". >>> The "stack" works (I have in production several apps relying on "web2py's >>> triggers"). After all, all your db(something).update() pass to the same >>> function that applies - conditionally - the triggers. >>> >>> PS: if the update fails, then the trigger fails too if you don't do a >>> db.commit() in the "trigger" itself. >>> All web2py's operations are handled in transactions, so it's "safe". >>> Moreover, all the before_* triggers have the "feature" that if that >>> function call returns "True" the update is not done.... kinda of an >>> additional validation (I use that in business logics, e.g., "you can't >>> delete the default mapping for a particular product category") >>> >>> -- >>> >>> >>> >>> >> >> > --
