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What I'm doing is getting a nodeset using find(), for example:

my $xp = XML::XPath->new(filename => $file); $plantdata->{nodeset} = $xp->find('//loop_device[@loop_number="1"]');
Which returns an XML::XPath::NodeSet.

Calling $plantdata->{nodeset}->get_nodelist() will return a list of XML::Node (and/or descendant) objects.

What I've done is go back to the beginning like this:

if ($devicetype eq "complex") { $seachstring = sprintf "//loop_device[@devicename=\"%s\"]/subdevice" +, $devicename; $subdevice = $xp->find($searchstring); }
That's unnecessary, using $device (which in your case is an XML::XPath::Node object returned from $nodeset->get_nodelist())as the context is fine.

I'm doing this because $device is a node from a node list not from a nodeset so I can't do this:

$subdevice = $device->find('/subdevice');
Yes, you can :-). The synopsis in the XML::XPath::NodeSet documentation shows that usage pattern.

I don't know the structure of your XML (you've not provided a sample), but that is exactly how this sort of this is usually done.

If I go into the debugger and look at $plantdata->{nodeset} and $device both seem to contain a hell of a lot more than just the node I want. Is there a way to turn a $device node back into a nodeset so that I can dig deeper into it rather than going back to $xp and starting again?
Now, why would you use a debugger to look in the XML::XPath::Node object? ;)

Actually, every node object returned from the initial XPath context has a references back to the main XPath context's XML DOM. That's likely what you're seeing in the debugger.

XML::XPath::Node objects must have the full context, otherwise you couldn't perform XPath queries like


because the context wouldn't be there to traverse!

The moral of the story is to use DOM methods to traverse the XML DOM, not a debugger.


In reply to Re: nodelists and nodesets by erroneousBollock
in thread nodelists and nodesets by nonnonymousnonk

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