12.3.4 Outputting XML: asXML()This is NOT the latest copy of this book; click here for the latest version.
One of the most interesting features about SimpleXML is that it can, at any time, give you a string containing the well-formed XML representation of its data. This essentially does the opposite of simplexml_load_file(), but the best bit about it is that it incorporates any changes you've made to the data whilst it was in SimpleXML form.
For example:
$xml = simplexml_load_file('employees.xml');
$xml->employee[1]->age = 55;
echo $xml->asXML();
That loads our XML file, and changes the second employee (remember, it's a zero-based array, so the 1 actually refers to the second element) to have an age of 55. The call to asXML() then outputs the changed data tree, printing this:
<?xml version="1.0"?>
<employees>
<employee>
<name>Anthony Clarke</name>
<title>Chief Information Office</title>
<age>48</age>
</employee>
<employee>
<name>Laura Pollard</name>
<title>Chief Executive Officer</title>
<age>55</age>
</employee>
</employees>
Note the changed value for Laura's age. However, blindly changing values isn't a smart move: the XML could change quite easily so that Pollard was no longer the second person in there. Instead, you should really combine it with an XPath search, like this:
<?php
$xml = simplexml_load_file('employees.xml');
echo "\nBefore transformation:\n\n";
echo $xml->asXML();
$xml->employee[1]->age = 55;
$employees = $xml->xpath('/employees/employee[name="Anthony Clarke"]');
$employees[0]->title = "Chairman of the Board, Chief Information Office";
echo "\n\nAfter transformation:\n\n";
echo $xml->asXML();
?>
This time the age is changed by referencing Laura directly, but I've also changed the job title of Anthony Clarke using a smart XPath search for his exact name. Of course, even names can be duplicated by chance, so an employee ID would be even better!
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