Flex Examples

In a previous example, “Preventing branches from being selected in a Flex Tree control”, we saw how we could prevent users from selecting branches (folders) in a Tree container in Flex by using the itemClick event and the Tree class’s dataDescriptor.isBranch() method.

The following example shows you how you can prevent any item from being selected by adding an attribute (named “clickable”, but you could name it anything you wanted) and using E4X expressions to determine if the currently clicked item should be selectable or not.

Full code after the jump.

Note that in the following example, items with the “(X)” suffix are not-selectable, only the following nodes should be selectable: “Grandchild 1″, “Grandchild 2″, and “Child 4″.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/01/16/preventing-specific-items-from-being-selected-in-a-flex-tree-control/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white"
        creationComplete="init();">

    <mx:Script>
        <![CDATA[
            import mx.events.ListEvent;

            private function init():void {
                tree.openItems = dp..node;
            }

            private function tree_itemClick(evt:ListEvent):void {
                var item:Object = evt.currentTarget.selectedItem;
                var nonSelectable:Boolean = ((item.hasOwnProperty("@clickable")) && (item.(@clickable == "false")));
                if (nonSelectable) {
                    tree.selectedItem = null;
                }
            }
        ]]>
    </mx:Script>

    <mx:XML id="dp">
        <root>
            <node label="Parent 1 (X)" clickable="false">
                <node label="Child 1 (X)" clickable="false" />
                <node label="Child 2 (X)" clickable="false">
                    <node label="Grandchild 1" />
                    <node label="Grandchild 2" />
                </node>
                <node label="Child 3 (X)" clickable="false" />
                <node label="Child 4" />
            </node>
        </root>
    </mx:XML>

    <mx:Tree id="tree"
            dataProvider="{dp}"
            showRoot="false"
            labelField="@label"
            width="200"
            itemClick="tree_itemClick(event);" />

</mx:Application>

View source is enabled in the following example.

For more information on disabling list selection in the List/Tree/ComboBox controls, see Alex Harui’s excellent blog entry, “Disabling List Selection”.