ProductVariant.pm

package MyContainer;
use 5.010;
use Moose;
use Bread::Board::Declare;

has config => (
    isa       => 'Config::Merge',
    is        => 'bare',
    lifecycle => 'Singleton'
    block     => sub { Config::Merge->new('/path/to/config'); },
):

has conn => (
  isa          => 'DBIx::Connector',
  dependencies => [ qw( config ) ],
  lifecycle    => 'Singleton',
  handles      => ['dbh'],
  is           => 'bare',
  block        => sub {
       my $s = shift;
       my $config = $s->param('config');
                 return DBIx::Connector->new( $config->('db.dsn'), $config->('db.user'), $config->('db.pass') );
            },
        );
    },
);

has controller => (
	isa   => 'MyController',
	is    => 'bare',
	infer => 1,
);

has product_repository => (
	isa       => 'Repository::Product',
	is        => 'bare',
	lifecycle => 'Singleton',
	infer     => 1,
);
 
package Role::DBH;
...
use Module::Runtime qw( use_module );
 
has _conn => (
	isa      => 'DBIx::Connector',
	is       => 'ro',
	required => 1,
);
 
package Repository::Product;
with 'Role::DBH';

sub get {
	... #deal with input and sql creation
	
	my $data = $self->_conn->dbh...
	
	... # transform the data structure
	
	return Product->new({ _conn => $self->_conn, %{ $data } });

}

package Product;
with 'Role::DBH';

sub variants {
	... #deal with input and sql creation
	
	my $data = $self->_conn->dbh->...
	
	... # transform the data structure
	my @variants;
	foreach my $params ( @$data ) {
	    ProductVariant->new({ _conn => $self->_conn, %{ $data } });
	}
	return @variants;
}

package ProductVariant;
with 'Role::DBH';
 
sub categories {
	... #deal with input and sql creation
	
	my $data = $self->_conn->dbh->...
	
	... # transform the data structure
	my @cats;
	foreach my $params ( @$data ) {
	    push @cats, Category->new({ _conn-> => $self->_conn, %{ $data } });
	}
	return @cats;
}

package Categories;
with 'Role::DBH';

package MyController;
use Moose;

has _products => (
	isa      => 'Repository::Product',
	is       => 'ro',
	required => 1,

sub do_the_needful {
	...
	
	my @variants = $self->_products->get($id)->variants;
	
	foreach my $variant ( @variants ) {
		my @cats = $variants->categories;
	}  
}