Why are my values not "taking"?

Question

I've had this problem intermittently, and now it's back and I
don't know why.
I have 2 datagrids with drag and drop. The source is an
XMLList, as in:
<items>
<item ln1="Feta" ln2="crumbled feta" sn="feta" minQy="0"
maxQy=".5" qty=".5" units="cup" />
<item ln1="Fontina" ln2="shredded Fontina" sn="fontina"
minQy="0" maxQy=".5" qty=".5" units="cup" />
... etc ...
</items>
For the destination, I have created an ArrayCollection to
receive the dropped items. One column is a numeric stepper:
<mx:DataGridColumn dataField="@qty" headerText="Quantity"
width="70" itemEditor="myComponents.NSEditor"
itemRenderer="myComponents.NSEditor"
editorDataField="newTotal"/>
Which uses this component:
<mx:Script>
<![CDATA[
public function get newTotal ():Number{
return step.value;
]]>
</mx:Script>
<mx:NumericStepper id="step" minimum="{XML(data).@minQy}"
maximum="{XML(data).@maxQy}" stepSize=".25"
value="{XML(data).@qty}" width="50"/>
</mx:VBox>
I check the totals in the list with:
// adds up the quantities, returns sum
public function getTotal(_arr:ArrayCollection) : Number {
var _sum : Number = 0;
var _length : Number = _arr.length;
for(var i:Number=0; i<_length; i++) {
var _item : Object = _arr.getItemAt( i );
var _value : Number = _item["@qty"];
_sum += _value;
return _sum;
The problem is, I drag a couple of items over, their default
qty is 0.5 as indicated in the XML. But even if I change the
steppers to 0.25, I'm still getting a total as if they're 0.5. Why
is this?

Answer 1

Make the getter newTotal bindable:
[Bindable}
public function get newTotal():Number{ ... }
You may get either an error or warning telling you that you
have to have a setter for newTotal as well. If you do, just add the
setter, even though it won't do anything.
Another approach would be to have a public variable in your
NS component:
[Bindable]
public var changedQuantity:Number
<mx:NumericStepper id="step" minimum="{XML(data).@minQy}"
maximum="{XML(data).@maxQy}" stepSize=".25"
value="{XML(data).@qty}" width="50"
change="changedQuantity=step.value" />
and then
<mx:DataGridColumn dataField="@qty" headerText="Quantity"
width="70" itemEditor="myComponents.NSEditor"
itemRenderer="myComponents.NSEditor"
editorDataField="changedQuantity"/>
TS