ah, the example code I provided just assigns an empty string to $BusUrl, which you later use as an object (my bad). so really, what you'd want to do is something like this: 
if($@) {
  # assign an empty (but defined) string to $bus_url
  $bus_url = '';
}
else {
  # assign tag contents to $bus_url
  $bus_url = $BusUrl->item(0)->getChildAtIndex(0)->getData(); 
}

[download]
 what you really want to do is follow mirod's advice and use the hasChildNodes method (note that he uses a much more flexible implementation than the following): 
my $BusUrl = $contact->getElementsByTagName( "BusinessUrl" );

# check if tag is defined and has children
if (defined $BusUrl && $BusUrl->hasChildNodes) {
  $bus_url = $BusUrl->item( 0 )->getChildAtIndex( 0 )->getData();
}
# otherwise assign an empty string
else {
  $bus_url = '';
}

[download]

__________
The trouble with having an open mind, of course, is that people will insist on coming along and trying to put things in it.
- Terry Pratchett

In reply to Re^3: use XML::DOM - what to do with empty tags? by EvanK
in thread use XML::DOM - what to do with empty tags? by kevyt

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