XPath API:
XML used to make our flash applications more dynamic.
The native XPathAPI class allows us to search the XML nodes and attributes within XML that’s loaded in to flash.
Simple XML Structure:
Â
loading xml:

The basic actionscript code for loading XML in actionscript 2.0
var xml:XML = new XML();
xml.ignoreWhite = true;
xml.onLoad = function( isLoaded:Boolean )
{
 if(isLoaded)
 {
  // here this refers to the xml object. Instead of this we can also use xml there.
  trace( this );
//trace( XML );
 }else
 {
  trace(”XML loading error”);
 }
}
xml.load( “XML/store.xml” );
Output:
Entire xml content.

Explanation:

var xml:XML = new XML();
Declaring the xml object that holds the externally loaded XML data.
xml.ignoreWhite = true;
Ignoring the unwanted whitespaces in loaded XML.
xml.onLoad = function(){}
onLoad function triggered once the xml is loaded using xml.load method is called. onLoad function also checks whether the load is success or not.

Importing XPath API:

First step before using Xpath Api is to import the XPathAPI class. This will make us to use the methods of the XPathAPI in our code.
Import mx.xpath.XPathAPI;
Or
mx.xpath.XPathAPI.[methodName]

XPath API methods:

selectNodeList()
selectSingleNode()
XPathAPI.getEvalString()
XPathAPI.setNodeValue()

getEvalString:

A string that represents the code required to access the value specified by the path parameter from the parent node.

import mx.xpath.XPathAPI;

var xml:XML = new XML();
xml.ignoreWhite = true;
xml.onLoad = function( isLoaded:Boolean )
{
 if(isLoaded)
 {
  //trace( this );
  // or
  //trace( XML )
  var myEvalString_str:String = XPathAPI.getEvalString(this.firstChild,”store/item/name”);
  trace(”getEvalString: ” + myEvalString_str);
 //output
  //getEvalString: this.firstChild.childNodes.0.childNodes.0.firstChild.nodeValue
  //we can use this to locate the value, for example
  //add this.firstChild infront bcoz we give this as the first argument for getEvalString.
  //replace childNodes.0 with childNodes[0]
  trace(this.firstChild.childNodes[0].childNodes[0].firstChild.nodeValue)
 //Outputs Pencil
 }else
 {
  trace(”XML loading error”);
 }
}
xml.load( “XML/store.xml” );

Explanation:

Outputs:
 getEvalString: this.firstChild.childNodes.0.childNodes.0.firstChild.nodeValue
 this method is useful to locate the value, for example
 add this.firstChild infront bcoz we give this as the first argument for getEvalString.
replace childNodes.0 with childNodes[0], this forms this.firstChild.childNodes[0].childNodes[0].firstChild.nodeValue
now trace the value and see
 trace(this.firstChild.childNodes[0].childNodes[0].firstChild.nodeValue)

selectNodeList:

Method returns an array of nodes matching the given XPathAPI statement.
import mx.xpath.XPathAPI;

var xml:XML = new XML();
xml.ignoreWhite = true;
xml.onLoad = function( isLoaded:Boolean )
{
 if(isLoaded)
 {
  //trace( this );
  // or
  //trace( XML )
  var nodeList_arr : Array = XPathAPI.selectNodeList(this.firstChild,”store/item/name”);
  trace(”selectNodeList: ” + nodeList_arr);
  //output
  //selectNodeList: <name>Pencil</name>,<name>Eraser</name>,<name>NoteBook</name>
  //nodeList_arr contains collection of XMLNodes with nodeName as name
  //to get the values from XMLNodes use looping statements
  for(i=0;i<nodeList_arr.length;i++)trace(”Value :”+nodeList_arr[i].firstChild.nodeValue);
 }else
 {
  trace(”XML loading error”);
 }
}
xml.load( “XML/store.xml” );

//output
//selectNodeList: <name>Pencil</name>,<name>Eraser</name>,<name>NoteBook</name>
//Value encil
//Value :Eraser
//Value :NoteBook

Explanation:

store/item/name – defines the path of node name (name)
we cal also use
*/*/name
This retrives the XMLNodes with nodeName –name, selectNodeList returns array.
To get the nodeValues we need to use looping statements to loop through the array.

SelectSingleNode:

This XPathAPI method retives the XMLNode which matches the query we can also use AND, OR statements while using the query.
import mx.xpath.XPathAPI;

var xml:XML = new XML();
xml.ignoreWhite = true;
xml.onLoad = function( isLoaded:Boolean )
{
 if(isLoaded)
 {
  //trace( this );
  // or
  //trace( XML )
  var xmlNode:Array = XPathAPI.selectNodeList(this.firstChild,”store/item[@id='1']“);
  trace(”selectSingleNode: ” + xmlNode);
  //output
  //selectSingleNode: <item id=”1″><name>Pencil</name><price>10</price><code>1120</code></item>
  //Here the query retives the node which has the attribute id =’1′
 }else
 {
  trace(”XML loading error”);
 }
}
xml.load( “XML/store.xml” );

Download Macromedia XPathAPI documentation

Download source files