XML error at ampersand (&)

Question

I have a php file which prints an xml based on a MySql db.

I get an error every time at exactly the point where there is an & sign.

Here is some php:

$query = mysql_query($sql);

$_xmlrows = '';

while ($row = mysql_fetch_array($query)) {
    $_xmlrows .= xmlrowtemplate($row);
}

function xmlrowtemplate($dbrow){
    return "<AD>
              <CATEGORY>".$dbrow['category']."</CATEGORY>
            </AD>
}

The output is what I want, i.e. the file outputs the correct category, but still gives an error.

The error says: xmlParseEntityRef: no name

And then it points to the exact character which is a & sign.

This complains only if the $dbrow['category'] is something with an & sign in it, for example: "cars & trucks", or "computers & telephones".

Anybody know what the problem is?

BTW: I have the encoding set to UTF-8 in all documents, as well as the xml output.

Answer 1

& in XML starts an entity. As you haven't defined an entity &WhateverIsAfterThat an error is thrown. You should escape it with &.

$string = str_replace('&', '&', $string);

How do I escape ampersands in XML

To escape the other reserved characters:

function xmlEscape($string) {
    return str_replace(array('&', '<', '>', '\'', '"'), array('&amp;', '&lt;', '&gt;', '&apos;', '&quot;'), $string);
}

Answer 2

$string = htmlspecialchars($string, ENT_XML1);

Using htmlspecialchars() with ENT_XML1 constant is the most universal way to solve all encoding errors (IMHO better that writing a custom function, also there are other entities to encode than &).

Credit: Put Wrikken's and joshweir's comment as answer to be more visible.