Load PHP variables into XML file - php

Question

So, what i am trying to achieve is to load variables from PHP into an XML file.
this is how my XML looks at the moment:
<?xml version="1.0" encoding="ISO-8859-1"?>
<firstname></firstname>
<lastname></lastname>
And this is my PHP where i try to save the variables into the XML
$file = simplexml_load_file("filename.xml");
$xml->firstname = "Mark";
$xml->lastname = "Zuckerberg";
file_put_contents($file, $xml->asXML());
If i try to print this i get following error message:
Call to undefined method stdClass::asXML() in ... on line 1374
Any suggestions?

Answer 1

You don't create the initial XML file, the library you are using creates it for you.
XML DOM is a fine choice for this job.
$xml = new DOMDocument(); # Create a document
$xml_firstname = $xml->createElement("firstname", "Over"); # Create an element
$xml_lastname = $xml->createElement("lastname", "Coder"); # Create an element
$xml->appendChild($xml_firstname); # Add the element to the document
$xml->appendChild($xml_lastname); # Add the element to the document
$xml->save("myfancy.xml"); # Save the document to a file
The output would be
<?xml version="1.0" encoding="utf-8"?>
<firstname>Over</firstname>
<lastname>Coder</lastname>

Answer 2

Enable error reporting (like error_reporting( E_ALL );) and you will understand quickly why it does not work:
Warning: simplexml_load_file(): xml.xml:3: parser error : Extra content at the end of the document
// your XML is not correctly formatted (XML requires a root node)
Warning: Creating default object from empty value
// $xml->firstname when $xml does not exists
To resolve that, your XML should looks like this:
<?xml version="1.0" encoding="ISO-8859-1"?>
<data><!-- here comes the root node -->
<firstname></firstname>
<lastname></lastname>
</data>
And the PHP should looks like previous answers:
$xml = simplexml_load_file("filename.xml");
$xml->firstname = "Mark";
$xml->lastname = "Zuckerberg";
file_put_contents("filename_copy.xml", $xml->asXML());

Answer 3

First off: where do you establish $xml?
You start with $file = ... but then refer to the object as $xml.
Either change the object name to $xml or change the references to $file:
$xml = simplexml_load_file("filename.xml"); /* note the object name change */
$xml->firstname = "Mark";
$xml->lastname = "Zuckerberg";
Next, your file_put_contents() command is incorrect. The first parameter is accepts is the filename, however in your example $file is not a name but a simplexml object.
file_put_contents("path/to/file.xml", $xml->asXML());
Alternatively, use the asXML() method with the path by doing this (thanks bassxzero):
$xml->asXML("path/to/file.xml");
Finally, your script is outputting the error:
Call to undefined method stdClass::asXML()
This implies that you can't call $xml->axXML() as (I'm assuming) either the method doesn't exist, or the object doesn't have the correct method.
Changing the name of the object initially (the first issue) should fix this!

Answer 4

From the code, you load the XML into $file.
But you edit $xml. The below code should work
$xml = simplexml_load_file("filename.xml");
$xml->firstname = "Mark";
$xml->lastname = "Zuckerberg";
file_put_contents("output.xml", $xml->asXML());