How to append XML data without overwriting? - php

Question

I'm in the process of writing an XML file:
<?php
$xml2 = "currenttest";
$xml = new DOMDocument("1.0");
$root = $xml->createElement ('tv');
$xml->appendChild($root);
$root->appendChild($xml->createTextNode("\n"));
$root->appendChild($xml->createTextNode($xml2));
$root->appendChild($xml->createTextNode("\n"));
$xml->save('epg.xml');
XML:
<?xml version="1.0"?>
<tv>
test
</tv>
If i change the text and again runs the code, the old content is deleted.
And I want the old text to stay.
Let's say this:
<?xml version="1.0"?>
<tv>
currenttest...
newtest...
</tv>
My previous way was to write the XML with:
file_put_contents($file, $xml2, FILE_APPEND | LOCK_EX);
FILE_APPEND | LOCK_EX, its helped me that the previous text would not be erased
I found a solution in another post:
$doc->loadXML(file_get_contents('epg.xml'));
foreach($doc->getElementsByTagName('***') as $node)
{
}
But how can it fit into my code?

Answer 1

You have nothing particular to do, just to reload your xml string and to append a new text node to your root element:
// your previous code (I only changed the variable names and added a default encoding)
$text = "currenttest";
$dom = new DOMDocument("1.0", "UTF-8");
$root = $dom->createElement('tv');
$dom->appendChild($root);
$root->appendChild($dom->createTextNode("\n"));
$root->appendChild($dom->createTextNode($text));
$root->appendChild($dom->createTextNode("\n"));
$xml = $dom->saveXML();
// let's add a new element
$newtext = 'newtext';
$dom = new DOMDocument;
$dom->loadXML($xml);
$root = $dom->documentElement; // conveniant way to target the root element
// but you can also write:
//$root = $dom->getElementsByTagName('tv')->item(0);
$root->appendChild($dom->createTextNode($newtext));
$newxml = $dom->saveXML();
echo $newxml;
demo
About $doc->loadXML(file_get_contents('epg.xml'));, note that you don't need to use file_get_contents since DOMDocument has already two methods:
DOMDocument::loadXML that loads the xml content from a string.
DOMDocument::load that loads the xml content directly from a file.
In addition to DOMNode::appendChild that adds a node to an element after all the children nodes of this element, you have also DOMNode::insertBefore to add a node to an element before the child node of your choice.

Answer 2

I tryed the code on top, 'cause i was overwriting my data, but when I coded in my application, it didn't worked cause I was trying to add the new node data in the loaded xml, you have to create a root to add data inside.
$xml = new DOMDocument("1.0", "UTF-8");
//an tag root must be first thing to add
$root = $xml->createElement('root');
$xml->appendChild($root);
Then, just add the data when you need
$xml = new DOMDocument("1.0", "UTF-8");
$xml->load($sFilepath);
$root = $xml->getElementsByTagName('root')->item(0);
your structure must looks like this:
<xml version="1.0" encoding="UTF-8">
<root>
</root>
The answer on top is totally correct. This answer is only to help if somebody is having trouble to understand.