Using a custom context menu with the Flex DataGrid control

I saw this question come up on a list today and thought this was pretty handy. Plus, I think it is the first time I’ve had a chance to play with the ContextMenu and ContextMenuItem classes in Flex in quite a while.

The following example pops up a custom context menu when the user right-clicks on an item in an data grid. After selecting the custom item (“View item…”) from the context menu an Alert control is displayed showing the selected item’s properties.

Full code after the jump.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/08/20/using-a-custom-context-menu-with-the-flex-datagrid-control/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white"
        creationComplete="init()">

    <mx:Script>
        <![CDATA[
            import mx.controls.Alert;

            [Bindable]
            private var cm:ContextMenu;

            private var alert:Alert;

            private function init():void {
                var cmi:ContextMenuItem = new ContextMenuItem("View item...", true);
                cmi.addEventListener(ContextMenuEvent.MENU_ITEM_SELECT, contextMenuItem_menuItemSelect);

                cm = new ContextMenu();
                cm.hideBuiltInItems();
                cm.customItems = [cmi];
                cm.addEventListener(ContextMenuEvent.MENU_SELECT, contextMenu_menuSelect);
            }

            private function contextMenu_menuSelect(evt:ContextMenuEvent):void {
                dataGrid.selectedIndex = lastRollOverIndex;
            }

            private function contextMenuItem_menuItemSelect(evt:ContextMenuEvent):void {
                var obj:Object = dataGrid.selectedItem;
                alert = Alert.show("Property A: " + obj.@propertyA + "\\n" + "Property B: " + obj.@propertyB, obj.@label, Alert.OK);
            }
        ]]>
    </mx:Script>

    <mx:XML id="itemsXML">
        <items>
            <item label="Item 1" data="i001" propertyA="Item 1.A" propertyB="Item 1.B" />
            <item label="Item 2" data="i002" propertyA="Item 2.A" propertyB="Item 2.B" />
            <item label="Item 3" data="i003" propertyA="Item 3.A" propertyB="Item 3.B" />
            <item label="Item 4" data="i004" propertyA="Item 4.A" propertyB="Item 4.B" />
            <item label="Item 5" data="i005" propertyA="Item 5.A" propertyB="Item 5.B" />
            <item label="Item 6" data="i006" propertyA="Item 6.A" propertyB="Item 6.B" />
            <item label="Item 7" data="i007" propertyA="Item 7.A" propertyB="Item 7.B" />
            <item label="Item 8" data="i008" propertyA="Item 8.A" propertyB="Item 8.B" />
        </items>
    </mx:XML>

    <mx:Number id="lastRollOverIndex" />

    <mx:DataGrid id="dataGrid"
            width="400"
            dataProvider="{itemsXML.item}"
             contextMenu="{cm}"
             itemRollOver="lastRollOverIndex = event.rowIndex">
        <mx:columns>
            <mx:DataGridColumn id="labelCol"
                    dataField="@label"
                    headerText="Label:" />

            <mx:DataGridColumn id="propACol"
                    dataField="@propertyA"
                    headerText="Property A:" />

            <mx:DataGridColumn id="propBCol"
                    dataField="@propertyB"
                    headerText="Property B:" />
        </mx:columns>
    </mx:DataGrid>

    <mx:Label text="{dataGrid.selectedItem.@label}" />

</mx:Application>

View source is enabled in the following example.