XML::LibXML issue finding XML nodes with a namespace

Question

I am writing an XML parser and am having an issue with the program handling a link. I am attempting to parse an XML hierarchy Settings/Setting then findnode 'Value'. The following is an example of the XML:

<?xml version='1.0' ?>
<Settings xmlns='http://hme.com/Settings.xsd'>
  <Setting SID="0">
    <Name>Store ID</Name>
    <Value>72</Value>
  </Setting>
  <Setting SID="1">
    <Name>Deprecated</Name>
    <Value>0</Value>
  </Setting>
  <Setting SID="8">
    <Name>Open Store Hours Sunday</Name>
    <Value>25200</Value>
  </Setting>

Here is the code I am using to parse the XML

my $doc = $parser->parse_file($settings_file) or die "Couldn't parse timer settings\n";

#Sunday
for my $reviewer ($doc->findnodes('/Settings/Setting[@SID="8"]')) {
  my ($name) = $reviewer->findnodes('Value');
  $name->removeChildNodes();
  $name->appendText('109800');
}

When I remove the xmlns='http://hme.com/Settings.xsd' from the XML file, there is no issue with replacing the value node. Once I enter the link back in the XML, the code stops working and will not update the xml sheet. Is there a way to handle for this link or to remove it so I can properly update the file?

You might find the "Working with namespaces" section from my tutorial useful. — Grant McLean
– Grant McLean, Commented Jan 28, 2020 at 20:05
Looking over the page you suggested I believe I am declaring the namespace correcr but am getting an XPath error: Undefined namespace prefix. I used the xpath sandbox and was able to load in my xml and use the query to find the node but when I attempt in my code no luck. This is how im declaring the namespace my $xpc = XML::LibXML::XPathContext->new(); $xpc->registerNs('xsd', 'http://hme.com/Settings.xsd'); — Taylor Stevens
– Taylor Stevens, Commented Jan 30, 2020 at 16:11

ikegami · Accepted Answer · 2020-01-27 18:37:56Z

3

You ask to find nodes with namespace null and with name Settings. There are no such nodes in the document, so findnodes correctly returns nothing.

You want to find the nodes with namespace http://hme.com/Settings.xsd and with name Settings. You can use the following to achieve that:

my $xpc = XML::LibXML::XPathContext->new();
$xpc->registerNs( s => 'http://hme.com/Settings.xsd' );

for ($xpc->findnodes('/s:Settings/s:Setting[@SID="8"]'), $doc) {
   ...
}

edited Jan 27, 2020 at 18:37

answered Jan 27, 2020 at 18:32

ikegami

391k17 gold badges291 silver badges555 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Taylor Stevens · Accepted Answer · 2020-01-30 19:27:28Z

0

I was able to get this working using this code.

my $dom = XML::LibXML->load_xml(location => $filename);

my $xpc = XML::LibXML::XPathContext->new($dom);
$xpc->registerNs('xsd',  'http://hme.com/Settings.xsd');

my($match1) = $xpc->findnodes('//xsd:Settings/xsd:Setting[@SID="8"]/xsd:Value');
$match1->removeChildNodes();
$match1->appendText('23400');

answered Jan 30, 2020 at 19:27

Taylor Stevens

816 bronze badges

5 Comments

Taylor Stevens Over a year ago

If anyone is looking at this in the future and needs help, this tool helped me alot. grantm.github.io/perl-libxml-by-example/_static/xpath-sandbox/…

ikegami Over a year ago

That's the same thing I posted 3 days earlier (except you made it a lot worse by using // instead of /).

Taylor Stevens Over a year ago

@ikegami sorry I made it "a lot worse" I wasn't getting it to work with your code. Could be user error, I'm still trying to learn.

ikegami Over a year ago

The code is identical except in two places: 1) You used xsd instead of s as the prefix, but choice of prefix doesn't matter. 2) You used // instead of /, which is very expensive for no reason, and it could lead to incorrect results.

Taylor Stevens Over a year ago

@ikegami thats my bad I guess, like I said I am no expert today and was even less so 3 years ago.

Collectives™ on Stack Overflow

XML::LibXML issue finding XML nodes with a namespace

2 Answers 2

Comments

5 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

5 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related