package MyApp::Location;

use base qw/DBIx::Class/;
...
__PACKAGE__->add_columns(
...
    location => {
        data_type => 'point',
    },

);
...
# custom result set
my $source = __PACKAGE__->result_source_instance();
my $new_source = $source->new( $source );
$new_source->source_name( 'ClosestUsers' );
$new_source->name( \qq{
( SELECT c.*,
    GLength(LineStringFromWKB(
       LineString(AsBinary(c.location), AsBinary(?))))
  AS distance
  FROM loc c 
  ORDER by distance asc
  LIMIT ?)
});
MyApp->register_source( 'ClosestUsers' => $new_source );
...