{
    my $rev_types = {
        both    => [qw/rev theater_avg num_theaters/],
        total   => [qw/rev             num_theaters/],
        loc_avg => [qw/    theater_avg num_theaters/],
        all     => [qw/rev theater_avg num_theaters day_multiple/],
    };

    sub _rev_types {
        my $key = @_ ? shift : 'both';
        exists $rev_type->{$key}?
          @{$rev_types->{$key}} :
          @{$rev_types->{'both'}};
    }
}

sub _select_fields {
    my $self = shift;
    return _rev_types( $self->request->param('rev_type'));
}