newbie_ab has asked for the wisdom of the Perl Monks concerning the following question:

I am trying to replace one element of XML document with a new element using XML::Twig. The element value file does not change in the player.xml. I am new to this module

Here is the code snippet: 

use strict;
use warnings;
use XML::Twig;
use Data::Dumper;

my $twig = XML::Twig->new();
$twig->parsefile( "player.xml");    # build the twig
my $root= $twig->root;
$root->set_tag( 'stats_test');
$root->print;

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And the sample XML file(player.xml): 

<stats>
    <player>
        <name>Houston, Allan</name>
        <g>69</g>
        <ppg>20.1</ppg>
        <rpg>3.4</rpg>
        <apg>2.8</apg>
        <blk>14</blk>
    </player>
    <player>
        <name>Sprewell, Latrell</name>
        <g>69</g>
        <ppg>19.2</ppg>
        <rpg>4.5</rpg>
        <apg>4.0</apg>
        <blk>15</blk>
    </player>
    <player>
        <name>Ewing, Patrick</name>
        <g>49</g>
        <ppg>14.6</ppg>
        <rpg>10.0</rpg>
        <apg>1.0</apg>
        <blk>68</blk>
    </player>
    <player>
        <name>Johnson, Larry</name>
        <g>57</g>
        <ppg>11.1</ppg>
        <rpg>5.3</rpg>
        <apg>2.6</apg>
        <blk>7</blk>
    </player>
</stats>

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Any help will be appreciated . Thanks ab

Replies are listed 'Best First'.
Re: Not able to replace element value using XML::Twig
by Anonymous Monk on Jan 24, 2010 at 23:56 UTC
    Your example code actually works as expected. Are you sure you're looking at the replacement file? It's a bit easier to do the same thing with handlers: 
    my $twig = XML::Twig->new(
    twig_handlers => { 
        stats => sub { $_->set_tag( 'stats_test' ) } 
    } );
$twig->parse_file(...);
$twig->flush;

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    as per the documentation.
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[d/l]

      Thanks , I ran the code snippet you had posted but got the following error : Can't locate object method "parse_file" via package "XML::Twig" at ./xml_twig_test.thpl line 14. Isn't parse_file is a function which belongs to XML::LibXML package Thanks ab

[reply]
        Try parsefile instead of parse_file.

        XML::Twig is an exceptionally well-documented CPAN module, and the parsefile method is described in its POD.

        There are many ways to search for information. Just typing "xml twig parse_file" into Google returns: 

        Did you mean: xml twig parsefile  Top 2 results shown

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Re: Not able to replace element value using XML::Twig
by jethro (Monsignor) on Jan 25, 2010 at 00:16 UTC

    Your script seems to work fine. When I ran it, the substitution took place.

    I don't know if there is a difference between $root->print and $twig->print, example code in the docs uses the latter but it didn't have any effect on my test runs. If you still have problems, you might use $twig just to be sure (even though I doubt it has something to do with it)

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      Thanks , the file player.xml should be replaced with the change but it is not. I am able to see the change using $twig->print. Hope that makes sense.

[reply]
        Ahh, that's the problem. You have to tell Twig explicitely to save it to a file (after all, a Twig user might not want to change the xml but just parse it, or print it to the screen).
        When I add 
         
$twig->print_to_file("player.xml");

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        at the end of your script instead of the "$root->print;" line, the file on disk gets updated too

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