Description:
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I would like to query my XML file with XPath using starts-with.
This is an example of my XML file:
<?xml version="1.0" encoding="utf-8"?>
<graphml>
  <graph id="G" edgedefault="directed">
    <node id="4">
      <data key="label">name</data>
      <data key="value">Alanine</data>
      <data key="node_path">moldb.molecule.name</data>
    </node>
  </graph>
</graphml>

I want to query to the node having the "node_path" attribute beginning by "moldb". But this didn't work. After trying many cases, I think it came from the XML structure that has more than one "data" nodes. If there is only one "data" node, it worked.

Reproduce code:
---------------
Here is my code:
$doc = new DomDocument(); // document to be explored
if (!$doc->load("ex.xml"))
{
	return; // invalid file
}
$xpath = new DOMXPath($doc); // to search for the nodes we want
$data = 'moldb';
$query = "/graphml/graph/node[starts-with(data,'$data')]";
$query = "/graphml/graph/node[data[@key='node_path'] and starts-with(data,'$data')]";
$entries = $xpath->evaluate($query);
echo $entries->length."\n";

Expected result:
----------------
When executing this script, it should print:
1

Actual result:
--------------
The obtained result is:
0