Josh Schumacher: A PHP Developer » XML http://blog.joshschumacher.com The biggest and the best in the Northwest Fri, 14 Oct 2011 06:15:10 +0000 en hourly 1 http://wordpress.org/?v=3.3.1 Standardizing a way to represent an object in PHP http://blog.joshschumacher.com/2008/04/23/standardizing-a-way-to-represent-an-object-in-php/ http://blog.joshschumacher.com/2008/04/23/standardizing-a-way-to-represent-an-object-in-php/#comments Wed, 23 Apr 2008 06:20:04 +0000 Josh Schumacher http://blog.joshschumacher.com/2007/08/04/standardizing-a-way-to-represent-an-object-in-php/ During the process of designing our API at Treemo, one of the first major design implementation hurdles we had to overcome was how to standardize a way to define what data in an object was "exportable" and can later be transformed into XML. The solution that I came up with defines a Node and a NodeCollection object.

When deciding what the data structure should look like, I wrote some pseudo XML that we need to be able to model.

PLAIN TEXT
XML:
  1. <channel>
  2.         <owner name="testuser" email="test@test.com" />
  3.         <list name="foo">
  4.                 <item id="123">
  5.                         <files>
  6.                                 <image href="http://foo.bar.com" />
  7.                                 <3gp href="http://3gp.foo.bar.com" />
  8.                         </files>
  9.                 </item>
  10.         </list>
  11. </channel>

A Node has a (string) $type, (mixed) $attributes and (NodeCollection) $children. Using the above XML as a reference, our root node (let's call it $root) would have $type = 'channel' and no attributes. You would then add two nodes to the NodeCollection $children, owner and list. Owner would have $attributes of array('name'=>'testuser', 'email'=>'test@test.com') and $children would be an empty NodeCollection.

The biggest design decision made about NodeCollection was that NodeCollection implements Iterator. By implementing Iterator, you can later foreach over $children and it can loop through the elements with no problem. Implementing Iterator is a pretty cool design pattern - I'll have to write a post about it in the near future. The ability to foreach over $children helps tremendously when writing ExportNodeToXml.

Wrapping up, pseudo code to export and object to a Node that can later be transformed to XML would look like this:

PLAIN TEXT
PHP:
  1. class Channel implements iExportable {
  2.     public function toExportable() {
  3.         $root = new Node('channel');
  4.         $root->children->addNode(new Node('list', array('name'=>'testuser', 'email'=>'test@test.com'));
  5.         $root->children->addNode(new Node('list', array('id'=>'123'));
  6.         $root->children->getNode(2)->children->addNode(new Node('files')));
  7.         $root->children->getNode(2)->children->getNode(1)->children->addNode('image', array('href'=>'http://foo.bar.com'));
  8.         $root->children->getNode(2)->children->getNode(1)->children->addNode('3gp', array('href'=>'http://3gp.foo.bar.com'));
  9.     }
  10. }

]]> http://blog.joshschumacher.com/2008/04/23/standardizing-a-way-to-represent-an-object-in-php/feed/ 2