When you write $bus_url = $BusUrl->item( 0 )->getChildAtIndex( 0 )->getData(); you apply a method (getData) to an undef value ($BusUrl->item( 0 )->getChildAtIndex( 0 )), hence the error. You should first check whether $BusUrl has children, throught the appropriately named hasChildNodes method.

The easiest way would be to add a sub that would return the text of the element or undef (or the empty string if it's more convenient for you). While you're at it you could also improve that sub to make it resistent to extra whitespace in the elements: if you only look at the first child of the BusinessUrl element, chances are that one day it will be a line return, with the real data on the following line (and child). Using XPath (either by switching to XML::LibXML or by using XML::DOM::XPath (which is a shameless plug)) will give you a better chance at making your code less dependent on the formating of the XML data.

You use the following (untested) code by calling my $bus_url= field( $contact, 'BusinessUrl'). Note that it is still not great, as extra comments in the data for example would be returned as part of the content of the element.

  sub field
    { my( $parent, $tag)= @_;
      my @elts= $parent->getElementsByTagName( $tag);
      return unless( @elts);
      my $elt= $elts[0];
      return unless( $elt->hasChildNodes);
      return join( '', map { $_->getData } $elt->getChildNodes);
  }
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Yippie !!!! This works :) This works :)

Thanks for everyone's help :)

I would like to find good documentation with examples.

Thanks again for your help.

# declare lexical variable *outside the scope of the eval*
my $BusUrl;

# trap potential error
eval {
  $BusUrl = $contact->getElementsByTagName( "BusinessUrl" );
};
# check if tag retrieval failed
if($@) {
  # assign an empty (but defined) string
  $BusUrl = '';
}

$bus_url = $BusUrl->item( 0 )->getChildAtIndex( 0 )->getData();
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Thanks, That makes a lot of sense. I am still getting the error:

Can't call method "getData" on an undefined value at parse_xml.pl line
+ 87.
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New code:

my $Long = $contact->getElementsByTagName( "Longitude" );
my $long = $Long->item(0)->getChildAtIndex(0)->getData();

# declare lexical variable *outside the scope of the eval*
my $BusUrl;

# trap potential error
eval {
   $BusUrl = $contact->getElementsByTagName( "BusinessUrl" );
};

# check if tag retrieval failed
if($@) {
   # assign an empty (but defined) string
   #$BusUrl = '';
}

$bus_url = $BusUrl->item(0)->getChildAtIndex(0)->getData(); # line 87

# change phone number format
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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(); 
}
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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

Yes, the doc works great until I hit an empty tag. I know I will get empty tags so I want to prepare for it :)