Labelfunction in a datagrid

Question

maybe someone can help me out with this... i am able to get a labelfunction to work fine (it sums the totals of the dataprovider) like so:
in my datagridcolumn with id = "grid1" i have labelFunction="sumFunction"
my sumFunction looks like this:
        public function sumFunction(col:DataGridColumn):String
            var n:int = grid1.dataProvider.length;
            var sum:Number = 0;
            for (var i:int = 0; i < n; i++)
                sum += grid1.dataProvider[i][col.dataField];
            return parentApplication.currencyFormatter.format(sum);//.toFixed(2);
but i find i need to create a sumFunction for every datagrid with a different ID and i'm going to have many. i want to be able to reuse code (best practice) and reuse the same function for all grids. the problem is i dont know which grid to loop over the dataprovider for and return the result to. so i started doing something like this:
        public function sumFunction(dgName:String,col:DataGridColumn):String
            var n:int = this[dgName]dataProvider.length;
            var sum:Number = 0;
            for (var i:int = 0; i < n; i++)
                sum += int(this[dgName]dataProvider[i][col.dataField]);
            return parentApplication.currencyFormatter.format(sum);
but then my labelfunction needs another argument/parameter passed to it. oddly enough why doesn't the labelFunction work without passing in the col:DataGridColumn in the first example but now it doesnt once i add another argument/parameter to the function?
i was expecting this to then work if i changed the labelfunction on each datagrid to pass the id of the datagrid to let the sumFunction know which one to use:
labelFunction="sumFunction('grid2')"
this throws an error that i need another argument/parameter but i dont know what to pass in. i'm also getting errors about a string... anyone know how i can accomplish this?

Answer 1

but i'm not within that packaged AS file... i'm in an MXML file that uses it like this:
    <local:FooterDataGrid id="ptqGrid" x="10" y="487" width="940" itemClick="itemClickEvent('ptqGrid',event);" dataProvider="{parentApplication.Service.perfToQuota.lastResult}" rowCount="5">
        <local:columns>
            <local:FooterDataGridColumn headerText="Quota Description" width="180" dataField="quota_desc">
                <mx:DataGridColumn headerText="Totals:" width="180" textAlign="right"/>
            </local:FooterDataGridColumn>
            <local:FooterDataGridColumn headerText="Quota" dataField="quota" labelFunction="{parentApplication.price_labelFunc}" textAlign="right" >
                <mx:DataGridColumn labelFunction="sumFunction" dataField="quota" textAlign="right" />
            </local:FooterDataGridColumn>
            <local:FooterDataGridColumn headerText="Total Revenue" labelFunction="{parentApplication.price_labelFunc}" textAlign="right" dataField="tot_rev">
                <local:itemRenderer>
                <mx:Component>
                <mx:Label text="{parentApplication.currencyFormatter.format(data.tot_rev)}" textAlign="right" color="#0000FF"
                styleName="lblNoUnderline" buttonMode="true" useHandCursor="true"
                mouseOver="styleName='lblUnderline';" mouseChildren="false"
                mouseOut="styleName='lblNoUnderline';"/>
                </mx:Component>
                </local:itemRenderer>
                <mx:DataGridColumn labelFunction="sumFunction" dataField="tot_rev" textAlign="right" />
            </local:FooterDataGridColumn>
            <local:FooterDataGridColumn headerText="Target Earnings" textAlign="right" labelFunction="{parentApplication.price_labelFunc}" dataField="trgt_earn">
                <mx:DataGridColumn labelFunction="sumFunction" dataField="trgt_earn" textAlign="right" />                   
            </local:FooterDataGridColumn>
            <local:FooterDataGridColumn headerText="Total Earnings" textAlign="right" labelFunction="{parentApplication.price_labelFunc}" dataField="tot_earn">
                <local:itemRenderer>
                <mx:Component>
                <mx:Label text="{parentApplication.currencyFormatter.format(data.tot_earn)}" textAlign="right" color="#0000FF"
                styleName="lblNoUnderline" buttonMode="true" useHandCursor="true"
                mouseOver="styleName='lblUnderline';" mouseChildren="false"
                mouseOut="styleName='lblNoUnderline';"/>
                </mx:Component>
                </local:itemRenderer>   
                <mx:DataGridColumn labelFunction="sumFunction" dataField="tot_earn" textAlign="right" />
            </local:FooterDataGridColumn>
            <local:FooterDataGridColumn headerText="Achievement" textAlign="right" dataField="ach">
                <mx:DataGridColumn labelFunction="averageFunction" dataField="ach" textAlign="right" />                   
            </local:FooterDataGridColumn>
        </local:columns>
    </local:FooterDataGrid>
and here is my sumFunction that is giving me the problem and does not have access to the owner property:
        public function sumFunction(col:FooterDataGridColumn):String
            var n:int = ptqGrid.dataProvider.length;
            var sum:Number = 0;
            for (var i:int = 0; i < n; i++)
                sum += int(ptqGrid.dataProvider[i][col.dataField]);
            return parentApplication.currencyFormatter.format(sum);//.toFixed(2);