Flex Spark DropDownList selectedItem didn't update after dataProvider changed
- by Candy Chiu
I have two dataProvider's for one DropDownList. The following code can be compiled and run.
<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
xmlns:s="library://ns.adobe.com/flex/spark"
xmlns:mx="library://ns.adobe.com/flex/mx"
creationComplete="flipLast()"
minWidth="955" minHeight="600">
<fx:Script>
<![CDATA[
import mx.collections.ArrayCollection;
public function flipLast():void {
if( last ) {
list.dataProvider = dp1;
list.selectedItem = "Flex";
} else {
list.dataProvider = dp2;
list.selectedItem = "Catalyst";
}
last = !last;
}
public var last:Boolean = true;
public var dp1:ArrayCollection = new ArrayCollection( [ "Flex", "Air" ] );
public var dp2:ArrayCollection = new ArrayCollection( [ "Catalyst", "FlashBuilder" ] );
]]>
</fx:Script>
<s:VGroup>
<s:DropDownList id="list" requireSelection="true" />
<s:Label id="listSelectedItem" text="{list.selectedItem}" />
<s:Label id="listSelectedIndex" text="{list.selectedIndex}" />
<s:Button label="Flip" click="flipLast()" />
</s:VGroup>
</s:Application>
Scenario 1: dataProvider updated, but selectedIndex is the same.
At startup: [ listSelectedItem=Flex, listSelectedIndex=1 ].
Click Flip: dataProvider is updated, but still [ listSelectedItem=Flex, listSelectedIndex=1 ].
Scenario 2: dataProvider updated, selectedIndex is also updated.
At startup: [ listSelectedItem=Flex, listSelectedIndex=1 ].
Select Air from list: [ listSelectedItem=Air, listSelectedIndex=2 ].
Click Flip: dataProvider is updated, but still [ listSelectedItem=Catalyst, listSelectedIndex=1 ].
Seems to me that selectedItem is driven by selectedIndex. selectedItem updates only when selectedIndex updates. Shouldn't selectedItem be updated when dataProvider is updated? Is binding to selectedItem flawed?
