How to filter spark datagrid?

Question

SORRY, I TRY TO FILTER MY DATAGRID, BUT IT DOESN'T WORK.
WHAT'S WRONG IN THIS CODE?
IN THE DEBUG EVERYTHING IS OK UNTIL THE BOLD TEXT, BECAUSE THE DATAPROVIDER IN DATAGRID IS NOT FILTERED.
PLEASE HELP ME!!!
THANK YOU.
<?xml version="1.0" encoding="utf-8"?>
<s:View xmlns:fx="http://ns.adobe.com/mxml/2009"
        xmlns:s="library://ns.adobe.com/flex/spark" title="Albo" creationComplete="init(event)">
    <fx:Script>
        <![CDATA[
            import mx.events.FlexEvent;
            import spark.events.GridEvent;
            import spark.events.TextOperationEvent;           
            import spark.components.TextInput;           
            import spark.components.DataGrid;
            import mx.collections.ArrayList;
            protected function init(event:FlexEvent):void
                IngegneriXML.send();
            private function gridClickEvent(event:GridEvent):void
                navigator.pushView(Dettaglio, event.target.selectedItem);
            private function filterDataProvider(obj:Object, idx:int, arr:Array):Boolean
                var txt1:String = RicCogn.text;
                var txt2:String = obj._item.cognome.toString();
            if (txt1.toLowerCase() == txt2.toLowerCase())
                return true;
                return false;
            protected function RicCogn_changeHandler(event:TextOperationEvent):void
                var arr:Array = Grid1.dataProvider.toArray();
                var filteredArr:Array = arr.filter(filterDataProvider);
                Grid1.dataProvider =  new DataProvider(filteredArr);
                Grid1.dataProvider.refresh();
                var ara2:Array = Grid1.dataProvider.toArray();
                var ara3:Array = Grid1.dataProvider.toArray();
        ]]>
    </fx:Script>   
    <fx:Declarations>
        <s:HTTPService id="IngegneriXML" url="C:\AlboFlash\DatiXML\ingegneri.xml"/>
    </fx:Declarations>
    <s:TextInput x="0" y="0" id="RicCogn" change="RicCogn_changeHandler(event)"/>
    <s:DataGrid id="Grid1" x="0" y="80" dataProvider="{IngegneriXML.lastResult.ingegneri.ingegnere}" height="100%" width="100%" gridClick="gridClickEvent(event);">
        <s:columns>
            <s:ArrayList id="columns">
                <s:GridColumn dataField="cognome" headerText="Cognome" minWidth="100"/>
                <s:GridColumn dataField="nome" headerText="Nome" minWidth="100"/>
            </s:ArrayList>
        </s:columns>
    </s:DataGrid>
</s:View>

Answer 1

I made it :-)
I revealed the magic.
Actually without knowing it, I was misusing the ArrayCollection class and treating it as Model, while it was obviously designed for View purposes.
Now I'm using ArrayList for that, and then I create a new ArrayCollection for different views. Then I use newArrayCollection.list = myList and newArrayCollection.filterFunction = ...
This works for me.
My recomendation would be to improve the documentation a bit, so that it is clear that it is not recommended to use same ArrayCollection for multiple views.
Regards,
Dinko