XML generation problem?

Question

Hi I'm relatively new to Flex 2 and I have a question.
I'm generating an xml file from an oracle view and hope to
use it as the basis for a chart/data grid.
My generation process yields data something like this:
<list>
<commodity name="Laptop Computer" total="0">
<warehouse name="California" onhand="10"/>
<warehouse name="Viriginia" onhand="20"/>
<warehouse name="Washington" onhand="0"/>
</commodity>
<commodity name="Desktop Computer" total="0">
<warehouse name="Washington" onhand="9"/>
</commodity>
</list>
I've taken this generated xml and put it into a local file
for now.
When I attempt to load this data I get this error:
TypeError: Error #1009: Cannot access a property or method of
a null object reference.
at TestFileAccess/TestFileAccess::resultHandler()
at TestFileAccess/__srv_result()
at
flash.events::EventDispatcher/flash.events:EventDispatcher::dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at flash.net::URLLoader/flash.net:URLLoader::onComplete()
My mxml file looks something like this:
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="
http://www.adobe.com/2006/mxml"
layout="absolute" xmlns="*" paddingTop="3"
creationComplete="initApp()" pageTitle="Warehouse Levels">
<mx:Script>
<![CDATA[
import mx.collections.ArrayCollection;
import mx.rpc.events.*;
[Bindable]
private var commodData:Array;
[Bindable]
private var warehouseData:Array;
[Bindable]
public var slicedCommodData:ArrayCollection;
private function initApp():void
srv.send();
slicedCommodData = new ArrayCollection();
private function resultHandler(event:ResultEvent):void
commodData = event.result.list.name.source as Array;
warehouseData = new Array(commodData.length);
slicedCommodData.source = commodData;
var commodTotal:Number;
for (var x:Number = 0; x < commodData.length; x++)
warehouseData[x] = {name: commodData[x].name, onhand:0};
var warehouses:Array = commodData[x].warehouse.source as
Array;
commodTotal = 0;
for (var j:Number = 0; j < warehouses.length; j++)
commodTotal += warehouses[j].onhand;
commodData[x].total = commodTotal;
]]>
</mx:Script>
<mx:HTTPService id="srv" url="result.xml"
useProxy="false" result="resultHandler(event)"/>
<mx:Panel layout="absolute">
<mx:ColumnChart id="WarehouseTotals"
dataProvider="{slicedCommodData.source}">
<mx:horizontalAxis>
<mx:CategoryAxis dataProvider="{slicedCommodData.source}"
categoryField="Name"/>
</mx:horizontalAxis>
<mx:series>
<mx:ColumnSeries xField="Name" yField="Total"/>
</mx:series>
</mx:ColumnChart>
<mx:DataGrid dataProvider="{slicedCommodData.source}">
<mx:columns>
<mx:DataGridColumn headerText="Commodity"
dataField="Name"/>
<mx:DataGridColumn headerText="Total"
dataField="Total"/>
</mx:columns>
</mx:DataGrid>
</mx:Panel>
</mx:Application>
I'm wondering if something is wrong with my generated xml
data or if its something else. I did notice that my xml generation
doesn't always produce 3 warehouse tags for every commodity. Could
this be the problem?
Also, the reason the commodity tag's total is always 0 in the
xml is because this information is not captured in the view...I use
mxml to calculate that.
Thanks!

Answer 1

It seems that I played with it for a while and fixed it. The
problem was my xml data and the format my httpservice was
returning. First my xml data needed to be enclosed by <data>
and </data> tags not <list> and </list> tags.
Second my httpservice needed to have a result format of e4x. This
also caused me to have to change how I was handling the individual
xml properties of the data.
Anyway the fixed code looks like this for anyone that cares
and has gotten a similar error.
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="
http://www.adobe.com/2006/mxml"
xmlns="*" paddingTop="3" creationComplete="initApp()"
pageTitle="Warehouse Levels">
<mx:Script>
<![CDATA[
import mx.collections.XMLListCollection;
import mx.rpc.events.*;
[Bindable]
private var commodData:XMLList;
[Bindable]
public var slicedCommodData:XMLListCollection;
private function initApp():void
srv.send();
private function resultHandler(event:ResultEvent):void
commodData = event.result.commodity;
slicedCommodData = new XMLListCollection(commodData);
var commodTotal:Number;
var nextNum:Number;
for (var x:Number = 0; x < commodData.length(); x++)
var warehouses:XMLList = commodData[x].warehouse as XMLList;
commodTotal = 0;
for (var j:Number = 0; j < warehouses.length(); j++)
nextNum = 0;
nextNum = new Number(warehouses[j].@onhand);
commodTotal = commodTotal + nextNum;
var firstItem:Object = slicedCommodData.getItemAt(i);
firstItem.@total = commodTotal;
]]>
</mx:Script>
<mx:HTTPService id="srv" url="result.xml"
resultFormat="e4x" result="resultHandler(event)"/>
<mx:HDividedBox width="50%" height="100%">
<mx:ColumnChart id="WarehouseTotals"
dataProvider="{slicedCommodData}">
<mx:horizontalAxis>
<mx:CategoryAxis dataProvider="{slicedCommodData}"
categoryField="@name"/>
</mx:horizontalAxis>
<mx:series>
<mx:ColumnSeries xField="@name" yField="@total"/>
</mx:series>
</mx:ColumnChart>
</mx:HDividedBox>
<mx:HDividedBox width="50%" height="100%">
<mx:DataGrid dataProvider="{slicedCommodData}">
<mx:columns>
<mx:DataGridColumn headerText="Commodity"
dataField="@name"/>
<mx:DataGridColumn headerText="Total"
dataField="@total"/>
</mx:columns>
</mx:DataGrid>
</mx:HDividedBox>
</mx:Application>
Thanks for all of your help!