simpleXML how to add a new attribute to existing XML

Question

Hey i am looking to make a copy of an existing XML and add a new attribute to the top of it

My current xml is something like:

<?xml version="1.0"?>
<export>
  <config>
    <Exported Name="test">
      <values>
        <node name="yellow" />
        <node name="green" />
        <node name="red" />
      </values>
  </config>
</export>

and i just want to add an email field, i am conforming it to match with specs so i dont have control over changing the layout so i cant do for example

 <email value="myemail@gmail.com"></email>

so i am stuck to having it displayed as below

<?xml version="1.0"?>
<email>
  myemail@gmail.com
</email>
<export>
  <config>
    <Exported Name="test">
      <values>
        <node name="yellow" />
        <node name="green" />
        <node name="red" />
      </values>
  </config>
</export>

I have tried a bunch of things but i am struggling. tbh i cant figure out a way to just add the value of the email inside the email node, all the examples i found seem to tell you how to add an attribute and then a child inside it but i couldnt find an example to add just a value inside of email node.

What i was trying as a first step was just to have it add the attribute email so i could at least get that part working but i am also failing at that. Of course my ultimate aim is to get the email inside the node email but i am just showing this as an example of what i tried and failed at. I am using the php documentation example but i obviously am doing something wrong cause i get an error: String could not be parsed as XML

$xml_file = "testing.xml";
$xml_path = XML_PATH.$xml_file;

$add_email = new SimpleXMLElement($xml_path);
$add_email->addAttribute('address', 'myemail@gmail.com');
$email = $add_email->addChild('email');

echo '<PRE>';
print_r($add_email);
echo '</PRE>';

However if i do the following i can see the xml echoed fine so the path etc is fine, its how im structuring the code is where the problem is. Any hints on where im messing up?

$xml_file = "testing.xml";
$xml_path = XML_PATH.$xml_file;

$xml = simplexml_load_file($xml_path);
echo '<PRE>';
print_r($add_email);
echo '</PRE>';

The above outputs the xml fine.

Answer 1

As mentioned in comments, you are trying to create invalid XML and therefore the SimpleXML extension is of little use here. You need to use normal string manipulation. Here is a fragile (because it is matching on ?>) implementation:

<?php
$xml_file = "testing.xml";
$xml_path = XML_PATH . $xml_file;

$contents = file_get_contents($xml_path);
$contents = str_replace("?>", "?>\n<email>myemail@gmail.com</email>", $contents);

print_r($contents);
?>

Keep in mind that trying to pass the resulting XML into anything that expects valid XML will fail horribly.

The real question remains: why would you knowingly want to generate invalid XML in the first place?

Edit: To answer your comment from below:

Can someone explain what is happening here with the ?> is that just hidden text in an XML file at the start of each line?

No, it is not hidden, the ?> is right here:

<?xml version="1.0"?>
                   ^^
<export>
  ....
</export>

The PHP code that I added replaces that ?> with ?> a new line (\n) and the XML node that you wanted.