[Dbix-class] on_field_change DBIC hooks

Pedro Melo melo at simplicidade.org
Sun Jul 29 22:56:37 GMT 2007


On Jul 29, 2007, at 2:08 PM, Matt S Trout wrote:

> On Sun, Jul 29, 2007 at 09:36:09AM +0100, Pedro Melo wrote:
>> 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?

Class base for now. It solves my problem. but I don't mind to code it  
differently if somebody needs the others.

Personally I only need class hooks.

>> 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_)

Missed store_column, I'll take a look.

>> 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.

Thanks for the pointers. I knew about Class::Observable already, I've  
used it in the past.

Best regards,
Pedro Melo
Blog: http://www.simplicidade.org/notes/
XMPP ID: melo at simplicidade.org

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