Changing XML Tag value in Perl Script

[Rajpreet1985]

Greetings, Requirement goes like this. I have perl script reading from a MQ Series queue. This queue has messages in form of XML.For example- 1 message is like -

<CLIENT_INFO> <LOCATION> New York </LOCATION> <FIELD> FINANCE GROUP </FIELD> <NO_OF_WORKERS> 123 </NO_OF_WORKERS> </CLIENT_INFO>

My perl script reads messgaes from this queue, and drops them to another queue after creating a backup in a text file. My requirement is I have check the value of a particular tag for example, value of <FIELD>, if that is say "FINANCE GROUP", I have to change it to "FINANCIAL SYSTEMS" and then drop to the other queue. I tried below, but for some reason it did not work. COuld you please help. Pl note I would prefer doing below way or other wise I have XML Parser installed. Sample of my script -

# Connect to qmgr
$qmgr = MQSeries::QueueManager->new ( QueueManager => $hOpts{m}, AutoC
+onnect => 0)
        or die "Unable to instantiate MQSeries::QueueManager object\n"
+;

$qmgr->Connect() or die("Unable to connect to queue manager\n" .  "Com
+pCode => " . $qmgr->CompCode() . "\n" .  "Reason => " .
 $qmgr->Reason() .  " (", MQReasonToText($qmgr->Reason()) . ")\n");

# open input and output queues
my $qIn =MQSeries::Queue->new(QueueManager => $qmgr, Queue => $hOpts{i
+}, Options=>MQSeries::MQOO_INPUT_SHARED )
         or die "Unable to open queue $hOpts{i}" ;

my $qOut=MQSeries::Queue->new ( QueueManager => $qmgr, Queue => $hOpts
+{o}, Options=>MQSeries::MQOO_OUTPUT | MQSeries::MQPMO_S
ET_ALL_CONTEXT )
         or die "Unable to open queue $hOpts{o}" ;

until( $time_to_die )
{
        my $message = MQSeries::Message->new(MsgDesc=>{Persistence=>1}
+);

    # Get message from queue
        $result = $qIn->Get( Message => $message, Sync=>1, Wait=>-1 );
+      
my $msgDescRef = $message->MsgDesc;
my $data = $message->Data;
my $field_name = GetXMLValue($data, "FIELD");
if ($field_name eq 'FINANCE GROUP')
{

$field_name = 'FINANCIAL SYSTEMS';

$msgDescRef->{"FIELD"} = $field_name ;
}
        for(1..$num_retries) {
                $result = $qOut->Put( Message => $message, Sync => 1,
                                PutMsgOpts =>{ Options=>MQSeries::MQPM
+O_SET_ALL_CONTEXT ||
                                                                      
+          MQSeries::MQPMO_FAIL_IF_QUIESCING});
                if ($result > 0) { last; }
               
                sleep $time_to_wait;
        }

[GrandFather]

I can't tell what GetXMLValue does, but generally using a module such as XML::Twig is the smart way to handle XML parsing and manipulation problems. Consider:

#!/usr/bin/perl
use strict;
use warnings;
use XML::Twig;

my $t = XML::Twig->new(
    twig_roots               => {'CLIENT_INFO/FIELD' => \&convert},
    twig_print_outside_roots => 1
    );

$t->parse(*DATA);

sub convert {
    my ($t, $elt) = @_;
    my $txt = $elt->text();
    $elt->set_text('FINANCIAL SYSTEMS') if $txt =~ /FINANCE GROUP/i;
    $elt->print ();
}


__DATA__
<CLIENT_INFO> <LOCATION> New York </LOCATION> <FIELD> FINANCE GROUP </
+FIELD> <NO_OF_WORKERS> 123 </NO_OF_WORKERS> </CLIENT_INFO>

Prints:

<CLIENT_INFO> <LOCATION> New York </LOCATION> <FIELD>FINANCIAL SYSTEMS
+</FIELD> <NO_OF_WORKERS> 123 </NO_OF_WORKERS> </CLIENT_INFO>

[Rajpreet1985]

Thanks for your inputs. However problem in my case is my production environment has just XML::Parser . I am not allowed to download XML::Twig or any other module. So options are either to directly manipulate or use XML::Parser. I have not done XML parsing anytime earlier . Would appreciate your inputs. Thanks.

[GrandFather]

Well, you could spend the time to recreate the parts of XML::Twig that you need for this project, or you could convince "management" that there is a significant gain to be made by making an exception to the "can't use external modules" rule in this case, or see Yes, even you can use CPAN.

[sundialsvc4]

For tasks like this, I suggest using an XML manipulation package such as XML::Twig. (Or XML::Simple, although I have learned to prefer to use Twig because very few “simple” things stay that way for long.)

These packages will enable you to solve the problem swiftly:

1. Decode the XML statement, getting a handle to that statement.
2. Using the handle, issue an XPath expression which will (with no complicated code from you...!) search the XML tree for all occurrences of whatever you’re looking for.
3. Given the list of nodes returned from that XPath-search, use the appropriate methods of those nodes to make the necessary changes ... to those nodes or, as the case may be, to their neighbors.   (The node-references that you get back from your search point to those nodes in the tree.)
4. Convert the structure back into an output string.   Q.E.D.

It will surprise you how little code is actually required to accomplish this kind of task ... and to accomplish it quite thoroughly.   Without a doubt, the systems that your app is talking to, are using these same core libraries and techniques, no matter what language(s) they were written in.   Go and do likewise.™

[choroba]

I often use XML::XSH2 to manipulate XML:

create '<CLIENT_INFO> <LOCATION> New York </LOCATION> <FIELD> FINANCE 
+GROUP </FIELD> <NO_OF_WORKERS> 123 </NO_OF_WORKERS> </CLIENT_INFO>' ;
set /CLIENT_INFO/FIELD[text()=" FINANCE GROUP "] "FINANCIAL SYSTEM" ;