Selecting from Combobox with only one item

Question

I'm populating Comboboxes based on selections from other
comboboxes. I pick up the selection with the 'change' trigger,
however when you select the top item or if there is only one item,
the change route doesn't work. So I tried to use the 'click' and
even the 'close' triggers instead, but they give me an errors when
I try to access the companion ArrayCollections which hold the IDs
for the items in the list (as commented in the code). Any ideas how
to get this to update with just one selection?
<!-- The first three comboboxes populate the next one in
the list in a 'drilldown' approach -->
<mx:ComboBox minWidth="130" maxWidth="130" id="selectSys"
dataProvider="{sysOps.lastResult.system.data}"
change="fillComboBox(selectSys, selectSub, 'subsystem',
subOps, sysIDs, 1)" rowCount="10" />
<mx:ComboBox minWidth="130" maxWidth="130" id="selectSub"
dataProvider="{subOps.lastResult.system.data}"
change="fillComboBox(selectSub, selectDev, 'devices',
devOps, subIDs, 2)"/>
<mx:HTTPService id="sysOps" useProxy="false" method="GET"
result="sysIDs = sysOps.lastResult.system.id as
ArrayCollection;"
fault="mx.core.Application.application.handleFault(event);"
url="
http://localhost:8080/TomCustodes/rocket"/>
<mx:HTTPService id="subOps" useProxy="false" method="GET"
result="subIDs = subOps.lastResult.system.id as
ArrayCollection;"
fault="mx.core.Application.application.handleFault(event);"
url="
http://localhost:8080/TomCustodes/rocket"/>
// fill destination combobox based on selection from src
combobox
public function fillComboBox(src:ComboBox, dest:ComboBox,
type:String,
serv:HTTPService, idArray:ArrayCollection, element:int) :
void {
// choose ID from the associated ID array with the same
selecetedIndex
// error occurs as the idArray ArrayCollection comes up as
null
var selectedID:String = idArray.getItemAt(src.selectedIndex)
as String;
var params:Object = {};
params[type] = type;
var arg:String = "arg";
var argList:Array = new Array();
if (element > 1) {
var ind:int = selectSys.selectedIndex;
var sysName:String = sysIDs.getItemAt(ind) as String;
argList.push(sysName);
if (element > 2) {
ind = selectSub.selectedIndex;
var subName:String = subIDs.getItemAt(ind) as String;
argList.push(subName);
argList.push(selectedID);
params[arg] = argList;
serv.send(params);
Thanks!

Answer 1

I think the way I would go about that is having a result
function for the HTTPServices and set your array collections how
you are. Then after they are set I would check to see if the length
== 1 and if it does then recall your fillComboBox method for the
next combo box since there isn't a way for the user to change the
combo box they might as well have the next one already filled out.
The other approach you could take is after you set your array
collection to your result add dummy items via
myAC.addItemAt({label:"Choose one"}, 0); This will ensure the user
always has an item to change to.