I am using Perl and XML::DOM to parse an XML file. In the XML file, there are tags that don't appear in all of the entries. How do I check to see if they are there before I try to read in the value. I have tried a bunch of things and they don't seem to work. I always get a value of "Can't call method "getFirstChild" on an undefined value at...". I have posted a sample code with the associated xml file.

PERL FILE: 

#!/usr/bin/perl  -w
# File displayPipeTracer2.pl

use XML::DOM;
use Getopt::Long;

my $testXML = qw/textXML.xml/;
my $test4 = "";
my $parser = new XML::DOM::Parser;
my $doc = $parser->parsefile ($testXML);

foreach my $entry ($doc->getElementsByTagName('Entry')) {
    my $test1 = $entry->getElementsByTagName('test1')->item(0)->getFir
+stChild->getNodeValue;
    my $test2 = $entry->getElementsByTagName('test2')->item(0)->getFir
+stChild->getNodeValue;
    my $test3 = $entry->getElementsByTagName('test3')->item(0)->getFir
+stChild->getNodeValue;
    #if (defined $entry->getElementsByTagName('test 4')->item(0)->getF
+irstChild->getNodeValue) {
    #    $test4 = $entry->getElementsByTagName('test4')->item(0)->getF
+irstChild->getNodeValue;
    #}
    print "$test1, $test2, $test3";
    print ", $test4" if defined $test4;
    print "\n";
}

[download]
XML FILE: 
#!/usr/bin/perl  -w
# File displayPipeTracer2.pl

use XML::DOM;
use Getopt::Long;

my $testXML = qw/textXML.xml/;
my $test4 = "";
my $parser = new XML::DOM::Parser;
my $doc = $parser->parsefile ($testXML);

foreach my $entry ($doc->getElementsByTagName('Entry')) {
    my $test1 = $entry->getElementsByTagName('test1')->item(0)->getFir
+stChild->getNodeValue;
    my $test2 = $entry->getElementsByTagName('test2')->item(0)->getFir
+stChild->getNodeValue;
    my $test3 = $entry->getElementsByTagName('test3')->item(0)->getFir
+stChild->getNodeValue;
    #if (defined $entry->getElementsByTagName('test 4')->item(0)->getF
+irstChild->getNodeValue) {
    #    $test4 = $entry->getElementsByTagName('test4')->item(0)->getF
+irstChild->getNodeValue;
    #}
    print "$test1, $test2, $test3";
    print ", $test4" if defined $test4;
    print "\n";
}

[download]

In reply to Parsing an XML file with an undefined value by ravishi

Title:
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