gistfile1.PL

package MyApp::Model;
use DBIx::Skinny;
use MyApp::Model::Iterator;

{
    no warnigns 'redefine';

    *_get_sth_iterator = sub {
        my ($class, $sql, $sth, $opt_table_info) = @_;

        return MyApp::Model::Iterator->new(
            skinny         => $class,
            sth            => $sth,
            row_class      => $class->_mk_row_class($sql, $opt_table_info),
            opt_table_info => $opt_table_info
        );
    };
}

1;

gistfile2.PL

package MyApp::Model::Iterator;
use base qw/ DBIx::Skinny::Iterator /;

use strict;
use warnings;


sub to_json
{
    my $self = shift;
    my $data;

    while (my $row = $self->next) {
        push @$data, $row->get_columns;
    }

    return $data
         ? JSON::XS->new->pretty(1)->utf8->encode($data)
         : undef;
}


1;