That definitely works; method name as $scalar. Not sure where it's falling down for you. As someone allergic to any kind of string concatenation, implied or literal, might I suggest something more like this–

my @db_colnames = qw( lastname firstname middlename );

my $rs = $schema
    ->resultset('myTable')
    ->search({},
             { order_by => \@db_colnames });

for my $row ( $rs->all ) {
    my %data = $row->get_columns;
    print join("\t", @data{@db_colnames}), "\n";
}
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