[CDBI] meta_info and mapping tables

Matt S Trout dbix-class at trout.me.uk
Wed Nov 9 18:49:44 GMT 2005


On Wed, Nov 09, 2005 at 06:28:56PM +0000, William Ross wrote:
> >Is the mapping array always a single element for normal link tables
> >(linking two tables)?
> 
> Normally, yes.
> 
> >Or rather, when would the mapping array contain more than a single
> >element?
> 
> If you supply a list:
> 
>   Film->has_many( 'actors', [ 'Role' => 'actor', 'flatter' ] );
> 
> Each method will be called on the result of the last, so in this case  
> you'd get back the results of calling $role->actor->flatter.*
> 
> I suppose we could think of cases where it _might_ be useful to get  
> back something that the actor has_a:
> 
>   Film->has_many( 'cast_pictures', [ 'Role' => 'actor' => 'image' ] );
> 
> but I doubt that it would be a good idea to rely on the functionality.

I think it's basically designed to patch over the lack of join and prefetch
functionality; I've never found this useful under CDBI::Sweet or DBIx::Class.

-- 
     Matt S Trout       Specialists in Perl consulting, web development, and
  Technical Director    UNIX/Linux systems architecture and automation. Mail
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