PHP How to extract extended data from kml file - php

Question

I use the folowing PHP to extract the coordinates from a kml file:
$xml = simplexml_load_file('data.kml');
$data = $xml->Document->Folder->Placemark;
foreach ($data as $record) {
$coordinates = $record->MultiGeometry->Polygon->outerBoundaryIs->LinearRing->coordinates[0];
}
This works fine for the coordinates. But how can I Extact the ExtendedData?
The kml file I am using:
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:atom="http://www.w3.org/2005/Atom" xmlns="http://www.opengis.net/kml/2.2">
<Document>
<name>pc4_single_vlak</name>
<visibility>1</visibility>
<Schema name="pc4_single_vlak" id="kml_schema_ft_pc4_single_vlak">
<SimpleField type="xsd:string" name="pc4">
<displayName>pc4</displayName>
</SimpleField>
<SimpleField type="xsd:string" name="woonplaats">
<displayName>woonplaats</displayName>
</SimpleField>
<SimpleField type="xsd:string" name="wplnaam_uniek">
<displayName>wplnaam_uniek</displayName>
</SimpleField>
<SimpleField type="xsd:string" name="gemeente">
<displayName>gemeente</displayName>
</SimpleField>
<SimpleField type="xsd:string" name="provincie">
<displayName>provincie</displayName>
</SimpleField>
</Schema>
<Folder id="kml_ft_pc4_single_vlak">
<name>pc4_single_vlak</name>
<Placemark id="kml_1">
<name>kml_1</name>
<snippet></snippet>
<ExtendedData>
<SchemaData schemaUrl="#kml_schema_ft_pc4_single_vlak">
<SimpleData name="pc4">4001</SimpleData>
<SimpleData name="woonplaats">Tiel</SimpleData>
<SimpleData name="wplnaam_uniek">Tiel</SimpleData>
<SimpleData name="gemeente">Tiel</SimpleData>
<SimpleData name="provincie">Gelderland</SimpleData>
</SchemaData>
</ExtendedData>
<MultiGeometry>
<Polygon>
<outerBoundaryIs>
<LinearRing>
<coordinates>...</coordinates>
</LinearRing>
</outerBoundaryIs>
</Polygon>
</MultiGeometry>
</Placemark>
</Folder>
</Document>
</kml>
I tried all kinds of things, but I cant get it to work.

Answer 1

I'm not sure where the hiccup is, but hopefully this provides some clarity.
Let's get the ExtendedData parent:
echo $record->ExtendedData;
No attributes though, only children, let's get the schemaUrl from the first SchemaData child:
echo $record->ExtendedData->SchemaData[0]['schemaUrl'];
When getting attrributes, you access them as an index of the element.
Here's a working example

Answer 2

I found the solution to my own question :). I gues this isnt the best way to do it. But I used the folowing code to get to the different SimpleData fields:
echo $record->ExtendedData->SchemaData->SimpleData[0];
echo $record->ExtendedData->SchemaData->SimpleData[1];
echo $record->ExtendedData->SchemaData->SimpleData[2];
enz..
Again. I am sure there is a better solution to this. If someone knows, please comment!