DataGrid Sorting Issues

Question

Dear Good Sirs,
I have encountered a problem with an app of mine where i have a datagrid that i refresh every 30 seconds.  However on the refresh of the dataset i will loose the sorting that i have on my datagrid.  I have trailed the net for various work arounds but so far have been unsuccessful and would appreciate some advice as to how i might be able to get around this issue.  I take the data from a source url to provide and xml list.  Sample below.
//where the data is coming from
mx:HTTPService id="httpGetOffers" url="testURL" method="GET"
resultFormat="e4x" result="doxmltestlist(event)" fault="fault(event)" useProxy="false" />
//my xmllist
[Bindable] private var xmltestlist:XMLList;
/result set
private function doxmltestlist(evt:ResultEvent):void
xmltestlist = evt.result.r;
//my grid
<mx:Panel title="Offer Bonds Only">
<renders:CitiDataGrid id="dgtestsort" dataProvider="{xmltestlist}" rowCount="20" variableRowHeight="true"totalRowColor="0xCCCCCC" >
<renders:columns>
<mx:DataGridColumn dataField="1" headerText="test1 sortCompareFunction="{numericSortByField('x')}"/>
<mx:DataGridColumn dataField="2" headerText="test2" sortCompareFunction="{numericSortByField('autonegtotaloffers')}"/>
<mx:DataGridColumn dataField="3" headerText="test3"  sortCompareFunction="{numericSortByField('done')}"/>
</renders:CitiDataGrid> 
Thanks in advance for your assistance.
Patrick

Answer 1

If you are resetting the dataprovider, you will have to save and re-apply
the sort.  If the data items really aren't changing, it might be better to
find a way to update the current dataProvider.