[Dbix-class] on_field_change DBIC hooks

[Matt S Trout]

On Sun, Jul 29, 2007 at 09:36:09AM +0100, Pedro Melo wrote:
> Hi,
> 
> I implementing a "on_field_change" hook. External classes can hook  
> the DBIC model to observe (usually) status changes and start some  
> business logic processes. The reason I choose this approach is that  
> it creates a loosely coupled system, where I can add other components  
> later without going back and modifying old code.

Hook how?

On a class base, a schema object base, a resultsource base, a resultset
base, a per-object base?
 
> From my first look through the code, I think the set_column() is the  
> proper place to do this. But we could set_column() and then not update 
> ().

Or store_column if you only want -actual- sets rather than "maybe a set"
(the value equality and dirty_columns logic is in set_)

> So update() and look at the dirty columns is probably safer.
> 
> If I want to trigger on insert also, I also have to watch for insert().

Right.

> Another option is to create an InflateColumn::Trigger and use that,  
> but it might not be what people expect.

No. You might like to have a look at the implementation of CDBICompat::Triggers
and consider doing something similar for Class::Observer rather than
Class::Trigger though.

-- 
      Matt S Trout       Need help with your Catalyst or DBIx::Class project?
   Technical Director    Want a managed development or deployment platform?
 Shadowcat Systems Ltd.  Contact mst (at) shadowcatsystems.co.uk for a quote
http://chainsawblues.vox.com/             http://www.shadowcatsystems.co.uk/