Building XML Trees With PHP - Making Friends And Influencing People
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Now, while all this is fine and dandy, how about using all this new-found knowledge for something practical?

This next example does just that, demonstrating how the XMLTree class can be used to convert data stored in a MySQL database into an XML document, and write it to a file for later use. Here's the MySQL table I'll be using,

+----+------------------+-----------------------------------+-----------
+----+------------------+-----------------------------------+----
--+----------------+
| 
id | name             | address                           | tel
  |fax       
 
    |
+----+------------------+-----------------------------------+-----------
+----+------------------+-----------------------------------+----
--+----------------+
| 
 1 | Sam Spade        | 134, Dark Road, New York, NY      |
1-800-TOUGH-GUY |1-234-587-3636 
|
|  2 | The White Rabbit | Down The Rabbit Hole, Wonderland  | 56-78-5467
  
|56-78-2537 
    |
|  3 | Jack Liliput     | The Little House, Lilliput Island 
| None
  |None 
          |
+----+------------------+-----------------------------------+-----------
+----+------------------+-----------------------------------+----
--+----------------+

and here's what I want my target XML document to look like:

<?xml version="1.0"?>
<addressbook>

	<item id="1">
      <name>Sam 
Spade</name>
      <address>134, Dark Road, New York, NY</address>
 
 
    <tel>1-800-TOUGH-GUY</tel>
      <fax>1-234-587-3636</fax>
 
 	</item>

	<item 
id="2">
      <name>The White Rabbit</name>
  
 
   <address>Down The Rabbit 
Hole, Wonderland</address>
      <tel>56-78-5467</tel>
 
     <fax>56-78-2537</fax>
 
 	</item>

 	<item id="3">
      <name>Jack 
Liliput</name>
      <address>The 
Little House, Lilliput Island</address>
 
     <tel>None</tel>
      <fax>None</fax>
 
 	</item>

</addressbook>

With XMLTree, accomplishing this is a matter of a few lines of code. Here they are:

<?php

// include class
include("Tree.php");

// set output filename
$filename 
= 'addressbook.xml';

// instantiate object
$tree  = new XML_Tree();

// add 
the 
root element
$root =& $tree->addRoot("addressbook");

// open connection 
to 
database
$connection = mysql_connect("localhost", "joe", "secret") or die 
("Unable 
to
connect!");

// select database
mysql_select_db("db567") or die 
("Unable 
to 
select database!");

// execute query
$query = "SELECT * FROM addressbook";
$result 
= mysql_query($query) or die ("Error in query: $query. " .
mysql_error());

// 
iterate through rows and print column data
while ($row = mysql_fetch_array($result))
{

	// 
add child elements
	$item =& $root->addChild("item", NULL, array("id" => 
$row['id']));
	$name 
=& $item->addChild("name", $row['name']);
	$address 
=& $item->addChild("address", 
$row['address']);
	$tel =& $item->addChild("tel", 
$row['tel']);
	$fax =& 
$item->addChild("fax", $row['fax']);

}

// close 
database connection
mysql_close($connection);

// 
open file
if (!$handle = fopen($filename, 
'w')) 
{	
	print "Cannot open file ($filename)";
	exit;
}

// 
write XML to file
if 
(!fwrite($handle, $tree->get())) 
{
	print "Cannot write 
to file ($filename)";
	exit;
}

// 
close file    
fclose($handle);

?>

Pretty simple, once you know how it works. First, I've opened up a connection to the database and retrieved all the records from the table. Then I've instantiated a new document tree and iterated over the result set, adding a new set of nodes to the tree at each iteration. Finally, once all the rows have been processed, the dynamically generated tree is written to a file for later use.

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