Flex Examples
The following example shows how you can prevent selection of specific items in a Spark DropDownList control in Flex 4 by listening for the changing event and calling the preventDefault() method.
The following example(s) require Flash Player 10 and the Adobe Flex 4 SDK. To download the Adobe Flash Builder 4 trial, see http://www.adobe.com/products/flex/. To download the latest nightly build of the Flex 4 SDK, see http://opensource.adobe.com/wiki/display/flexsdk/Download+Flex+4.
For more information on getting started with Flex 4 and Flash Builder 4, see the official Adobe Flex Team blog.
<?xml version="1.0" encoding="utf-8"?> <!-- http://blog.flexexamples.com/2009/04/11/preventing-specific-item-selection-on-a-spark-dropdownlist-control-in-flex-gumbo/ --> <s:Application name="Spark_DropDownList_selectionChanging_test" xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" xmlns="library://ns.adobe.com/flex/mx"> <fx:Script> <![CDATA[ import mx.controls.Alert; import spark.events.IndexChangeEvent; protected function dropDownList_changingHandler(evt:IndexChangeEvent):void { var ddl:DropDownList = evt.currentTarget as DropDownList; if ((ddl.selectedItem != null) && (ddl.selectedItem.hasOwnProperty("selectable")) && (!ddl.selectedItem.selectable)) { evt.stopImmediatePropagation(); evt.preventDefault(); } } protected function dropDownList_changeHandler(evt:IndexChangeEvent):void { Alert.show("Spark DropDownList selection was changed."); } ]]> </fx:Script> <s:DropDownList id="dropDownList" labelField="label" prompt="Please select a string..." changing="dropDownList_changingHandler(event);" change="dropDownList_changeHandler(event);" width="200" horizontalCenter="0" top="10"> <s:dataProvider> <s:ArrayList> <fx:Object label="The" selectable="false" /> <fx:Object label=" Quick" /> <fx:Object label=" Brown" /> <fx:Object label=" Fox" /> <fx:Object label=" Jumps" /> <fx:Object label=" Over" /> <fx:Object label="The" selectable="false" /> <fx:Object label=" Lazy" /> <fx:Object label=" Dog" /> </s:ArrayList> </s:dataProvider> </s:DropDownList> </s:Application>
View source is enabled in the following example.
This entry is based on a beta version of the Flex 4 SDK and therefore is very likely to change as development of the Flex SDK continues. The API can (and will) change causing examples to possibly not compile in newer versions of the Flex 4 SDK.
Peter deHaan
Peter deHaan currently works for Adobe on the Flex SDK QA team. While not working on Flex, Flash, and ColdFusion applications, Peter enjoys making up bios and writing in 3rd person. Peter's rarely updated blog can be found at blogs.adobe.com/pdehaan/, actionscriptexamples.com, airexamples.com, and coldfusionexamples.com.
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