PHP htmlentities and saving the data in xml format - php

Question

Im trying to save some data into a xml file using the following PHP script:
<?php
$string = 'Go to google maps and some special characters ë è & ä etc.';
$string = htmlentities($string, ENT_QUOTES, 'UTF-8');
$doc = new DOMDocument('1.0', 'UTF-8');
$doc->preserveWhiteSpace = false;
$doc->formatOutput = true;
$root = $doc->createElement('top');
$root = $doc->appendChild($root);
$title = $doc->createElement('title');
$title = $root->appendChild($title);
$id = $doc->createAttribute('id');
$id->value = '1';
$text = $title->appendChild($id);
$text = $doc->createTextNode($string);
$text = $title->appendChild($text);
$doc->save('data.xml');
echo 'data saved!';
?>
I'm using htmlentities to translate all of the string into an html format, if I leave this out the special characters won't be translated to html format. this is the output:
<?xml version="1.0" encoding="UTF-8"?>
<top>
<title id="1">&lt;a href=&quot;google.com/maps&quot;&gt;Go to google maps&lt;/a&gt; and some special characters &euml; &egrave; &amp; &auml; etc.</title>
</top>
The ampersand of the html tags get a double html code: &lt; and an ampersand becomes: &amp;
Is this normal behavior? Or how can I prevent this from happening? Looks like a double encoding.

Answer 1

Try to remove the line:
$string = htmlentities($string, ENT_QUOTES, 'UTF-8');
Because the text passed to createTextNode() is escaped anyway.
Update:
If you want the utf-8 characters to be escaped. You could leave that line and try to add the $string directly in createElement().
For example:
$title = $doc->createElement('title', $string);
$title = $root->appendChild($title);
In PHP documentation it says that $string will not be escaped. I haven't tried it, but it should work.

Answer 2

It is the htmlentities that turns a & into &
When working with xml data you should not use htmlentities, as the DOMDocument will handle a & and not &.
As of php 5.3 the default encoding is UTF-8, so there is no need to convert to UTF-8.

Answer 3

This line:
$string = htmlentities($string, ENT_QUOTES, 'UTF-8');
… encodes a string as HTML.
This line:
$text = $doc->createTextNode($string);
… encodes your string of HTML as XML.
This gives you an XML representation of an HTML string. When the XML is parsed you get the HTML back.
how can I prevent this from happening?
If your goal is to store some text in an XML document. Remove the line that encodes it as HTML.
Looks like a double encoding.
Pretty much. It is encoded twice, it just uses different (albeit very similar) encoding methods for each of the two passes.