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How to remove elements from XML data?

by waxmop (Beadle)
on Apr 09, 2003 at 19:58 UTC ( #249394=perlquestion: print w/replies, xml ) Need Help??
waxmop has asked for the wisdom of the Perl Monks concerning the following question:

I need to delete some elements from an XML file, and I'm not sure how to do it intelligently.

I've got an XML file that looks sort of like this:

<opt> <node> <val>1</val> </node> <node> <val>2</val> </node> <node> <val>3</val> </node> </opt>
And I want to remove some arbitrary node based on user input. Here's what I've got so far, assuming that I want to remove the node that has the "val" attribute set to 2:
use strict; use XML::Simple; my $xref = XMLin("<top><node><val>1</val></node><node><val>2</val></no +de><node><val>3</val></node></top>"); my $nodenum = 0; for my $n ( @{$xref->{'node'}} ) { if ( $n->{val} == 2 ) { splice @{$xref->{'node'}}, $nodenum, 1; } $nodenum++; }
I really don't like using the $nodenum++ to track which element I'm iterating at, but I can't think of a better way.

Replies are listed 'Best First'.
•Re: How to remove elements from XML data?
by merlyn (Sage) on Apr 09, 2003 at 20:58 UTC
    Another strategy:
    use XML::LibXML; my $d = XML::LibXML->new->parse_string(join "", <DATA>); for my $dead ($d->findnodes(q{/opt/node[val = "2"]})) { $dead->unbindNode; } print $d->toString; __END__ <opt> <node> <val>1</val> </node> <node> <val>2</val> </node> <node> <val>3</val> </node> </opt>
    which results in:
    <?xml version="1.0"?> <opt> <node> <val>1</val> </node> <node> <val>3</val> </node> </opt>

    -- Randal L. Schwartz, Perl hacker
    Be sure to read my standard disclaimer if this is a reply.

Re: How to remove elements from XML data?
by jasonk (Parson) on Apr 09, 2003 at 20:46 UTC

    IMO, the grep route is the cleanest way:

    $xref->{node} = [grep { $_->{val} != 2; } @{$xref->{node}}];

    We're not surrounded, we're in a target-rich environment!
      I don't understand how you use this. $xref->{node} = [grep { $_->{val} != 2; } @{$xref->{node}}];
      which module you are using??

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