22 July 2008

Sort XML by Attribute in Actionscript 3

I love working with E4X, but I wish there was an easy way to sort an XML based on an attribute.

After looking around I couldn't really find a good solution or maybe people weren't explaining themselves correctly, or I wasn't googling correctly. So I decided just to write my own small utility class.

When I thought about it. Arrays provide a superb sortOn() function, and it's relatively easy to leverage that.

code

I created a sortXMLByAttribute() public static function in my XMLUtils Class

public static function sortXMLByAttribute
 	(
		$xml		:	XML,
		$attribute	:	String,
		$options	:	Object	=	null,
		$copy		:	Boolean	=	false
	)
	:XML
 {
	//store in array to sort on
	var xmlArray:Array	= new Array();
	var item:XML;
	for each(item in $xml.children())
	{
		var object:Object = {
			data	: item, 
			order	: item.attribute($attribute)
		};
		xmlArray.push(object);
	}

	//sort using the power of Array.sortOn()
	xmlArray.sortOn('order',$options);

	//create a new XMLList with sorted XML
	var sortedXmlList:XMLList = new XMLList();
	var xmlObject:Object;
	for each(xmlObject in xmlArray )
	{
		sortedXmlList += xmlObject.data;
	}
	
	if($copy)
	{
		//don't modify original
		return	$xml.copy().setChildren(sortedXmlList);
	}
	else
	{
		//original modified
		return $xml.setChildren(sortedXmlList);
	}
 }

say what?

Store XML in an array of objects, where one key is the "order" attribute we want to sort on.
Next we just call the Array.sortOn, with whatever options were passed
We then loop over sorted array and create a new XMLList
We then replace the children of original with sorted children

how to use

$xml : The XML that needs to be sorted
$attribute : The attribute string to sort on
$options : The sorting options, see sortOn()
$copy : If false, original XML is modified.

Here is an example, note this is in a package called XMLUtils

var xml:XML =
<body id="someId">
        <p displayOrder="15">Hello</p>
        <p displayOrder="7">World</p>
        <p displayOrder="3">Is</p>
        <p displayOrder="9">This</p>
        <p displayOrder="25">Thing</p>
        <p displayOrder="13">Working</p>
</body>

// original XML object
trace("BEFORE:" + xml);

XMLUtils.sortXMLByAttribute(
	xml,
	'displayOrder'
);
trace("After:" + xml);

XMLUtils.sortXMLByAttribute(
	xml,
	'displayOrder', 
	Array.NUMERIC
);
trace("Array.NUMERIC:" + xml");

//multiple options not don't modify orginal
var reverseXML:XML = XMLUtils.sortXMLByAttribute(
	xml,
	'displayOrder', 
	Array.NUMERIC | Array.DESCENDING, 
	true
);
trace("Array.NUMERIC | Array.DESCENDING:" + reverseXML);

source

Source code (in package+ + example) xmlutil.zip

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