I have an Advance Datagrid that is populated by an arraycollection. Although it
is not shown below, each object within the arraycollection has an individual id
attribute "GroupID". When I drag the

private function dragHandler(eragEvent):void{
var dg:AdvancedDataGrid = AdvancedDataGrid(e.currentTarget);
Alert.show(gc.grouping.fields);
Alert.show(dg.selectedItem.GroupID);

<mx:AdvancedDataGrid id="adg" width="100%" height="100%" y="30"
dragEnabled="true" dropEnabled="true" dragMoveEnabled="true">
<mx:dataProvider>
<mx:GroupingCollection id="gc" source="{arrItems}">
<mx:Grouping>
<mx:GroupingField name="Group"/>

</mx:Grouping>
</mx:GroupingCollection>
</mx:dataProvider>
<mx:columns>
<mx:AdvancedDataGridColumn dataField="Group" width="75"/>

<mx:AdvancedDataGridColumn dataField="Program" width="75"/>
<mx:AdvancedDataGridColumn dataField="Created_By" width="75"/>

<mx:AdvancedDataGridColumn dataField="Date_Created" width="130"/>


</mx:columns>
</mx:AdvancedDataGrid>

I haven't worked with ADG and reag/drop, but with regular DG:

var iTargetIndex:int = dg.calculateDropIndex(e);

With the index you can find the item in the dataProvider.

Tracy