Use qr/.../ to use a regular expression in a query .....
my $cursor = $collection->query({"name" => qr/[Jj]oh?n/});
##</code><code>##

{"name" => '/.*uba$/i'}

##</code><code>##

{"name" => 'qr/.*uba$/i'}

##</code><code>##

if(index($_[0],"qr/") >= 0){ 
				$_[0] =~s/qr(.*?)(i?)$/$1/s;
				print $fh Dumper($_[0]);
				if($2=='i'){
					my $re = qr/$_[0]/i;
				}else{
					my $re = qr/$_[0]/;
				}
				$_[0] =$re;
				print $fh Dumper($_[0]);
			}
##</code><code>##

$VAR1 = '/.*uba$/';
$VAR1 = undef;