PHP - XML Parsing (Trying to get property of non-object) - php

Question

Good morning!
I try to describe my problem: I have a language class and in the class there is a function Text(category, item).
so I can call the function like:
Language::Text("indexPage", "hello_world");
And the output would be:
Hello World!
The Values of the items are in a xml file.
Structure of my XML file:
<?xml version="1.0" encoding="UTF-8"?>
<languageBase>
<language filename="en" language="English">
<category name="indexPage">
<item name="hello_world"><![CDATA[Hello World!]]></item>
</category>
</language>
</languageBase>
But if I use the function Text(..), I get an error:
Trying to get property of non-object in
C:\xampp\htdocs\Mvc\system\classes\class.language.php on line 20
This is my class:
<?php
if (!defined("OK")) {
header("Location: ../");
}
class Language {
private static $_language = "de";
public static function params($string) {
$string = str_replace("%USERNAME%", User::GetUsername(User::$_id, 1), $string);
$string = str_replace("%#USERNAME%", User::GetUsername(User::$_id), $string);
return $string;
}
public static function Text($category, $item) {
$xml = new SimpleXMLElement(file_get_contents(self::GetPath()));
$category = "indexPage";
$item = "hello_world";
$obj = $xml->xpath("/languageBase/language/category[#name=\"{$category}\"]/item[#name=\"{$item}\"]");
return $obj->entry;
}
public static function Set($language) {
$_SESSION[SESSION_LANGUAGE] = $language;
}
public static function Get() {
if(isset($_SESSION[SESSION_LANGUAGE])) {
if(file_exists("system/lang/".$_SESSION[SESSION_LANGUAGE].".xml")) {
self::$_language = $_SESSION[SESSION_LANGUAGE];
}
} else {
$_SESSION[SESSION_LANGUAGE] = self::$_language;
}
return self::$_language;
}
public static function GetPath() {
return "system/lang/".self::Get().".xml";
}
}

Answer 1

You never define that you want to access the attribute called "name". There could be any number of other attributes like "id".
What you could do is use xpath like this:
public static function Text($category, $item) {
$xml = new SimpleXMLElement(file_get_contents(self::GetPath()));
$items = $xml->xpath("//category[#name='$category']/item[#name='$item']");
if ($items[0]) {
return (string)$items[0];
}
return null;
}
With this solution it is important to make sure that $category and $item never contains xpath control characters, i.e. $item = 'my[item]' would produce errors.
In that case, you would have to escape $item and $category somehow.
xpath is not always very straight forward to understand. A nice resource is: http://www.w3schools.com/xpath/xpath_syntax.asp