[Dbix-class] Hiding storage details

[Andreas Mock]

> -----Ursprüngliche Nachricht-----
> Von: "Jess Robinson" <castaway at desert-island.me.uk>
> Gesendet: 17.03.09 15:05:34
> An: "DBIx::Class user and developer list" <dbix-class at lists.scsys.co.uk>
> Betreff: Re: [Dbix-class] Hiding storage details

Hi Jess,

> Some diagrams would go a long way to explaining whats going on there.. let 
> me take some guesses:
> 
> Table O:
> ID   |  colour | attr2 
> ----------------------
> 1    |  red    | 2
> 2    | orange  | 4
> 3    | yellow  | 6
> 
> Table Attribute:
> O_id | Class   | Value
> ----------------------
> 1    | length  | 3cm
> 1    | height  | 4cm
> 3    | length  | 2cm
> 
> Anywhere close?

Best guess...  :-)

> And you'd like:
> 
>    my $row1 = $schema->resultset('O')->find(1);
> 
> $row1->colour - returns red
> $row1->length - returns '3cm'
> 
> which in normal dbic would be:
> 
> $row1->attributes->find({ Class => 'length'})->Value

Yes, this would expose the storage details to the "user" of the class.
But this sounds like there is also "abnormal" DBIC.  ;-)

> 
> > Is there a way in DBIC to do this?
> 
> There's always a way.. You can add more logic to your O class, so that its 
> transparent to the rest of the system.

> I think you'll need autoload in your O clas, aka:
> 
>    sub AUTOLOAD {
>      my $self = shift;
>      my $attr_name = $AUTOLOAD;
>      $attr_name  =~ s/.*://;
> 
>      my $attr = $self->attributes->find({ class => $attr_name });
> 
>      die "No such attribute $attr_name" if(!$attr);
> 
>      return $attr->value;
>    }
> 
> Not convinced this is the best solution.. maybe someone will come up with 
> a better one now I've suggested it!

Ok, that sounds feasible.
But other ideas are also welcome... 

Anyway, Jess, thank you for taking the time to outline a solution.

Best regards
Andreas Mock