How to modify an XML file using XML::DOM

ankit.tayal560 has asked for the wisdom of the Perl Monks concerning the following question:

I've written this code but the modifications are not reflecting in the xml file.am I missing something important in the code? confused about using perl in xml! would be glad if someone can help and explain in a detailed manner how to perform this task? I am getting output as Joey 67890

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

my $parser=new XML::DOM::Parser;

my $doc=$parser->parsefile('C:\perl\perl_tests\xmlin.xml') or die$!;
my $root=$doc->getDocumentElement();

my @address=$root->getElementsByTagName("address");

foreach my $address(@address)
{
    if($address->getAttribute("name") eq "tayal")
    {
        if($address->getAttribute("id")=='70889')
        {
         $address->setAttribute("name","Joey");
         $address->setAttribute("id","67890");
         my $temp1=$address->getAttribute("name");
         my $temp2=$address->getAttribute("id");
         print("$temp1\t$temp2\n\n");
         }
    }
}
XML FILE : <config logdir="var/log/foo/" debugfile="tmp/foo.debug">
<server name ="sahara" osname ="solaris" osversion="2.6">
<address name="ankit" id="70888"/>
<address name="tayal" id="70889"/>
</server>
<server name="gobi" osname="irix" osversion="6.5">
<address name="anshul" id="70689"/>
</server>
<server name="kalahari" osname="linus" osversion="2.0.34">
<address name="raghu" id="45678"/>
<address name="lucky" id="67895"/>
</server>
</config>
[download]

Comment on How to modify an XML file using XML::DOM Download Code

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Re: How to modify an XML file using XML::DOM by afoken (Chancellor) on Sep 28, 2016 at 05:54 UTC
You read the file into memory, and you modify the in-memory copy. Now, what is required to make the changes appear in the file? Hint: It's the same problem that every simple editor program has, and most editors are smart enough to ask you. Start the editor, open a text file, modify the copy in the editor's part of memory. Exit the editor. What does the editor ask you when attempting to exit? Second hint: Read the synopsis of XML::DOM. Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply]
Re^2: How to modify an XML file using XML::DOM by ankit.tayal560 (Beadle) on Sep 28, 2016 at 06:23 UTC
Okay, Got your point. I should write the contents into my xml file to see the changes. I tried this and gave me an error : can't call method "getEncoding" on an undefined value ... MODIFIED CODE : use strict; use warnings; use Data::Dumper; use XML::DOM; my $parser=new XML::DOM::Parser; my $doc=$parser->parsefile('C:\perl\perl_tests\xmlin.xml') or die$!; my $root=$doc->getDocumentElement(); my @address=$root->getElementsByTagName("address"); foreach my $address(@address) { if($address->getAttribute("name") eq "tayal") { if($address->getAttribute("id")=='70889') { $address->setAttribute("name","Joey"); $address->setAttribute("id","67890"); my $temp1=$address->getAttribute("name"); my $temp2=$address->getAttribute("id"); print("$temp1\t$temp2\n\n"); } } } open(INFILE,">C:/perl/perl_tests/xmlin2.xml"); $doc->printToFile("C:/perl/perl_tests/xmlin2.xml"); $doc->dispose; close(INFILE); [download]	[reply] [d/l]
Re^3: How to modify an XML file using XML::DOM by haukex (Archbishop) on Sep 28, 2016 at 06:50 UTC
Hi ankit.tayal560, You don't need the `open` and `close` - `printToFile` does all the handling of writing to the file for you. As for the error message, it appears you've come across a bug - or at least a deficiency in the documentation - of XML::DOM. The document needs to have an "XMLDecl" set. You can do this for example via: `$doc->setXMLDecl($doc->createXMLDecl('1.0','UTF-8'));` Hope this helps, -- Hauke D	[reply] [d/l] [select]
Re^4: How to modify an XML file using XML::DOM by ankit.tayal560 (Beadle) on Sep 28, 2016 at 10:28 UTC
Re^4: How to modify an XML file using XML::DOM by ankit.tayal560 (Beadle) on Sep 28, 2016 at 08:12 UTC
Re: How to modify an XML file using XML::DOM by choroba (Cardinal) on Sep 28, 2016 at 08:52 UTC
Just a note: much easier in xsh, a wrapper around XML::LibXML : `open xmlin.xml ; for /config/server/address[@name="tayal" and @id=70889] { set @name "Joey" ; set @id 67890 ; } save :b ;` [download] ($q=q:Sq=~/;[c](.)(.)/;chr(-\|\|-\|5+lengthSq)`"S\|oS2"`map{chr \|+ord }map{substrSq`S_+\|`\|}3E\|-\|`7**2-3:)=~y+S\|`+$1,++print+eval$q,q,a, [download]	[reply] [d/l] [select]
Re: How to modify an XML file using XML::DOM by Laurent_R (Canon) on Sep 28, 2016 at 06:12 UTC
You can't modify a sequential file like that. You are amending a copy of the file in memory, then you need to write back your modified content back to a file, either to a new copy of the original file or, if you are sure of what you're doing, back to the original file.	[reply]
Re^2: How to modify an XML file using XML::DOM by ankit.tayal560 (Beadle) on Sep 28, 2016 at 06:27 UTC
yes I got that point. tried this but gives me an error : can't call method "getEncoding" on an undefined value... use strict; use warnings; use Data::Dumper; use XML::DOM; my $parser=new XML::DOM::Parser; my $doc=$parser->parsefile('C:\perl\perl_tests\xmlin.xml') or die$!; my $root=$doc->getDocumentElement(); my @address=$root->getElementsByTagName("address"); foreach my $address(@address) { if($address->getAttribute("name") eq "tayal") { if($address->getAttribute("id")=='70889') { $address->setAttribute("name","Joey"); $address->setAttribute("id","67890"); my $temp1=$address->getAttribute("name"); my $temp2=$address->getAttribute("id"); print("$temp1\t$temp2\n\n"); } } } open(INFILE,">C:/perl/perl_tests/xmlin2.xml"); $doc->printToFile("C:/perl/perl_tests/xmlin2.xml"); $doc->dispose; close(INFILE); [download] .	[reply] [d/l]