Unable to parse atom feed - php

Question

I am implementing Youtube push notification and implemented webhook. Youtube gives updates in the form of atom feed. My problem is i can't parse that feed.
This is the XML:
<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:yt="http://www.youtube.com/xml/schemas/2015">
<link rel="hub" href="https://pubsubhubbub.appspot.com" />
<link rel="self" href="https://www.youtube.com/xml/feeds/videos.xml?channel_id=UCaNoTnXcQQt3ody_cLZSihw" />
<title>YouTube video feed</title>
<updated>2018-03-01T07:21:59.144766801+00:00</updated>
<entry>
<id>yt:video:vNQyYJqFopE</id>
<yt:videoId>vNQyYJqFopE</yt:videoId>
<yt:channelId>UCaNoTnXcQQt3ody_cLZSihw</yt:channelId>
<title>Test Video 4</title>
<link rel="alternate" href="https://www.youtube.com/watch?v=vNQyYJqFopE" />
<author>
<name>Testing</name>
<uri>https://www.youtube.com/channel/UCaNoTnXcQQt3ody_cLZSihw</uri>
</author>
<published>2018-03-01T07:21:48+00:00</published>
<updated>2018-03-01T07:21:59.144766801+00:00</updated>
</entry>
<?php
$xml = '<?xml versio......';
$obj = simplexml_load_string($xml);
echo '<pre>';print_r($obj);echo '</pre>';
Screenshot
How to get the value of yt:videoId element. I am new to PHP, if I did anything wrong please correct me.

Answer 1

It seems the XML elements containing the yt namespace (e.g. <yt:videoId>) are not being parsed by simplexml_load_string. I don't know why but in your case the video id is also present in the <id> element you just need to extract the last value or simply cut of yt:video: in front of it. That is at least an easy workaround.
Also it works if you use a direct XPath to the <yt:videoId> element like this:
echo $obj->xpath('//yt:videoId')[0];
// output: vNQyYJqFopE
XPath always returns an array so you need to get the first element with [0].

Answer 2

Try this (updated)
$str = $obj->entry->id;
echo substr($str, strpos($str, "video:")+ 6);
Get the channel
$chan = $obj->entry->author->uri;
echo substr($chan , strpos($chan , "channel/")+ 8);