The following example shows you how you can expand tree nodes (recursively, no less) by selecting an item from a ComboBox control.
Full code after the jump.
<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/11/29/opening-nodes-in-a-flex-tree-control-using-the-expanditem-method/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
layout="vertical"
verticalAlign="middle"
backgroundColor="white">
<mx:Script>
<![CDATA[
import mx.events.ListEvent;
private function comboBox_change(evt:ListEvent):void {
var team:String = ComboBox(evt.currentTarget).selectedItem.@label;
var node:XMLList = mlb.league.division.team.(@label == team);
expandParents(node[0]);
tree.selectedItem = node[0];
var idx:int = tree.getItemIndex(node[0]);
tree.scrollToIndex(idx);
}
private function expandParents(node:XML):void {
if (node && !tree.isItemOpen(node)) {
tree.expandItem(node, true);
expandParents(node.parent());
}
}
]]>
</mx:Script>
<mx:XML id="mlb" source="mlb.xml" />
<mx:ApplicationControlBar dock="true">
<mx:ComboBox id="comboBox"
prompt="Please select a team..."
dataProvider="{mlb.league.division.team}"
labelField="@label"
change="comboBox_change(event);" />
</mx:ApplicationControlBar>
<mx:Tree id="tree"
dataProvider="{mlb}"
labelField="@label"
showRoot="false"
width="300"
rowCount="8" />
</mx:Application>
View source is enabled in the following example.




By the way, there is a bug in the previous example. For cities that have multiple teams (Los Angeles, Chicago, New York) the first matching city is always returned. Sorry, I should have given each team a more unique ID than just a city name.
Peter
Hi, how do we do it with an ArrayColletion as the dataprovider?
A user on FlexCoders (http://tech.groups.yahoo.com/group/flexcoders/) was asking if you could use a Tree as a ComboBox dropdown. I cheated a little and just used the PopUpButton control instead, but for more information, see “Displaying a Tree control as a pop up for a Flex PopUpButton control”.
Peter
Cheers Buddy! I had been mucking around with expandItem() for a few hours and did not realize the tree will not “auto expand” you have to do it manually so thanks for that you just saved me another hour or so of mucking around (=