Add item to xml everytime form is submitted - xmlwriter PHP - php

Question

I have an html form when submitted post values to a php file. those values are then read into xmlwriter like below
<?php
$pastor= $_POST["Speaker"];
$title= $_POST["Title"];
$link= $_POST["podcasturl"];
$download= $_POST["Download"];
$podcastid= $_POST["Podcastid"];
$pubdate= $_POST ["Date"];
$xml = new XmlWriter();
$xml->openURI('podcast.xml');
$xml->formatOutput = true;
$xml->startDocument('1.0');
$xml->setIndent(4);
$xml->startElement("podcast");
$xml->writeElement('pastor', $pastor);
$xml->writeElement('title', $title);
$xml->writeElement('link', $link);
$xml->writeElement('download', $download);
$xml->writeElement('podcastid', $podcastid);
$xml->writeElement('pubdate', $pubdate);
$xml->endElement();
$xml->endElement();
$xml->endDocument();
?>
This whole system works fine. It creates the xml as I need it to based on the form. What I cant figure out is how to make it add a new item to the xml every time the form is submitted as opposed to it overwriting the same entry each time.
Thanks

Answer 1

You should consider using SimpleXML instead. XMLWriter is not intended to modify existing xml. From the XMLWriter introduction:
This extension represents a writer that provides a non-cached, forward-only means of generating streams or files containing XML data.
Using SimpleXML you can do something like this:
$xml = simplexml_load_file("podcast.xml");
$podcast = $xml->addChild("podcast");
$podcast->addChild("pastor", $pastor);
$podcast->addChild("title", $title);
$podcast->addChild("link", $link);
$podcast->addChild("download", $download);
$podcast->addChild("podcastid", $podcastid);
$podcast->addChild("pubdate", $pubdate);
$dom = new DOMDocument("1.0");
$dom->preserveWhiteSpace = false;
$dom->formatOutput = true;
$dom->loadXML($xml->asXML());
$dom->save("podcast.xml");
In order for this example to work the podcast xml elements should be wrapped in an element (see below) and the `podcast.xml' file should already exist. Although the latter can be overcome with a check before loading.
<?xml version="1.0"?>
<podcasts>
<podcast>...</podcast>
<podcast>...</podcast>
<podcasts>