Flex中datagrid数据过滤

<?xml version="1.0" encoding="utf-8"?>
<!-- http://yecon.blog.hexun.com/29904545_d.html -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">
    <mx:Script>
        <![CDATA[
            import mx.collections.*;
            import mx.events.ItemClickEvent;
            private var selectedRegion:String;
            public function regionFilterFunc(item:Object):Boolean 
            {
                if (selectedRegion=="all")
                    return true
                else
                    return item.region == selectedRegion;
            }
            public function filterAC(event:ItemClickEvent):void 
            {
                selectedRegion=event.label;
                myAC.filterFunction=regionFilterFunc;
                myAC.refresh();
            }
        ]]>
    </mx:Script>
    <mx:ArrayCollection id="myAC">
        <mx:Array id="myArray">
            <mx:Object state="LA" city="Baton Rouge" region="west"/>
            <mx:Object state="NH" city="Concord" region="east"/>
            <mx:Object state="TX" city="Austin" region="west"/>
            <mx:Object state="MA" city="Boston" region="east"/>
            <mx:Object state="AZ" city="Phoenix" region="west"/>
            <mx:Object state="OR" city="Salem" region="west"/>
            <mx:Object state="FL" city="Tallahassee" region="east"/>
            <mx:Object state="MN" city="Saint Paul" region="east"/>
            <mx:Object state="NY" city="Albany" region="east"/>
        </mx:Array>
    </mx:ArrayCollection>
    <mx:ToggleButtonBar id="tbb" horizontalGap="5" itemClick="filterAC(event);">
        <mx:dataProvider>
            <mx:Array>
                <mx:String>all</mx:String>
                <mx:String>east</mx:String>
                <mx:String>west</mx:String>
            </mx:Array>
        </mx:dataProvider>
    </mx:ToggleButtonBar>
    <mx:DataGrid id="dg" width="100%" height="100%" rowCount="5" dataProvider="{myAC}">
        <mx:columns>
            <mx:DataGridColumn dataField="state" headerText="State"/>
            <mx:DataGridColumn dataField="city" headerText="City"/>
            <mx:DataGridColumn dataField="region" headerText="region"/>
        </mx:columns>
    </mx:DataGrid>
</mx:Application>