CPAN::Forum
XML-Twig - Re: Checking a twig root for existence of element?
| Posted on Thu Jul 5 16:33:21 2007 by stevieray in response to 5637 (See the whole thread of 2) |
| Re: Checking a twig root for existence of element? |
|
Not sure if you want to test for existence ANYWHERE under the root or just the top level. Imagine an XML doc with the following structure -
<book>
<title>XML Wrapping</title>
<author>Hubie Illin</author>
<chapters>
<chapter num="1">
<title>Run XML</title>
<text>
If at first you don't succeed, parse, parse again.
</text>
</chapter>
</chapters>
<price>19.95</price>
</book>
You could test for given tags using something like the script below. I even added a test for the case of the title tag must not only exist, but exist under the chapter parent. You can probably change the syntax of the required tag list to include notation for nested tags like chapter:title and handle parsing them in the loop that tests the tags. Hope this helpsSteve
#!/usr/bin/perl
#=================================
# Program: check_tags.pl
#=================================
#
use strict;
use XML::Twig;
sub print_error;
my $filename = shift;
print_error "Filename is required" unless ($filename);
print "\n";
print "Parse file: $filename\n\n";
print_error "File not found : $filename" unless (-e $filename);
my @required = qw(title author price);
my %found_required = map { $_ => 0 } @required; # init all to not found
my $twig = new XML::Twig;
$twig->parsefile($filename);
my $root = $twig->root; # get the root of the twig
check_children($root);
for my $tag (sort keys %found_required) {
print "$tag: ", ($found_required{$tag}) ? "Found\n" : "NOT found\n"; }
exit;
#=====================================
sub check_children {
my $elem = shift;
my $tag = $elem->tag;
my $level = $elem->level;
my $path = $elem->path;
my $spacer = ' ' x $level;
print "${spacer}Level $level tag = $tag [$path]\n";
my $found = grep { $_ eq $tag } @required;
my @children = $elem->children; # get the child list
if ($found) {
if ($tag eq 'title') {
my $in_chapter = $elem->in_context('chapter');
$found_required{$tag} = 1 if ($in_chapter);
}
else {
$found_required{$tag} = 1;
}
}
if (@children) {
for my $child (@children) {
check_children($child);
}
}
}
#-------------------------------------
sub print_error {
my $msg = shift;
print STDERR "\nERROR>> $msg\n\n";
exit -1;
}
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