# step one:
 # set up a base method to make sure your item exists, and
 # store your item information in $c->stash

 sub base : Chained('/') PathPart('item') CaptureArgs(1) {

     my ($self, $c, $itemid) = @_;

     my $item = $c->model('Item')->find($itemid);

     if ( $item == undef ) {

         $c->stash( error_msg => "This item does not exist" );

         $c->detach("nonexistent");

     } else {

         $c->stash( item => $item );

     }

 }