Search for and replace values in a KML file - php

Question

I'm very new to php so go easy on me.
I'm trying to search through a KML file for latitude and longitude values, then replace them with user inputted lat/long values. The problem I'm having is actually searching through the KML file to find the specific lat/long values to be replaced.
KML:
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom">
<Folder>
<name>Folder-Name</name>
<open>1</open>
<gx:Tour>
<name class="name">Tour-Name</name>
<gx:Playlist>
<gx:FlyTo>
<LookAt>
<gx:horizFov>100</gx:horizFov>
<longitude class="lookat-long">33.33333</longitude>
<latitude class="lookat-lat">-111.11111</latitude>
<altitude>0</altitude>
<heading>0</heading>
<tilt>60</tilt>
<range>100</range>
<altitudeMode>relativeToGround</altitudeMode>
</LookAt>
</gx:FlyTo>
</gx:Playlist>
</gx:Tour>
</Folder>
</kml>
I need to replace "33.33333" and "-111.11111" with user inputted values. I have tried using SimpleXML, but it does not recognize the gx: part of the tag, since that is KML specific, and not part of XML. So when I try this code:
<?php
$xml = simplexml_load_file('my_kml_file');
print_r($xml)
?>
I get this output:
SimpleXMLElement Object ( [Folder] => SimpleXMLElement Object ( [name] => Temporary Places [open] => 0 ) )
It just stops at <open> because it doesn't recognize the rest. I have spent hours upon hours trying to figure out how to best do this and I just can't. Please help.

Answer 1

You can use the xpath method to get the namespaced node like so:
$xml = simplexml_load_file('my_kml_file');
$xml->xpath('//gx:Tour/gx:Playlist/gx:FlyTo')[0]->LookAt->longitude = 'newValue';
$xml->xpath('//gx:Tour/gx:Playlist/gx:FlyTo')[0]->LookAt->latitude = 'newValue';
print_r($xml->asXml());
Output:
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom">
<Folder>
<name>Folder-Name</name>
<open>1</open>
<gx:Tour>
<name class="name">Tour-Name</name>
<gx:Playlist>
<gx:FlyTo>
<LookAt>
<gx:horizFov>100</gx:horizFov>
<longitude class="lookat-long">newValue</longitude>
<latitude class="lookat-lat">newValue</latitude>
<altitude>0</altitude>
<heading>0</heading>
<tilt>60</tilt>
<range>100</range>
<altitudeMode>relativeToGround</altitudeMode>
</LookAt>
</gx:FlyTo>
</gx:Playlist>
</gx:Tour>
</Folder>
</kml>