Setting a label function on a Spark List control in Flex 4

In a previous example, “Setting a label field on a Spark List control in Flex 4”, we saw how you could set the label field on the Spark List control in Flex 4 by setting the labelField property.

The following example shows how you can set a custom label function on a Spark List control in Flex 4 by setting the labelFunction property.

The following example(s) require Flash Player 10 and the Adobe Flex 4 SDK. To download the Adobe Flash Builder 4 trial, see www.adobe.com/products/flex/. To download the latest nightly build of the Flex 4 SDK, see 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/2009/03/08/setting-a-label-function-on-a-fxlist-control-in-flex-gumbo/ -->
<s:Application name="Spark_List_labelFunction_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009" 
        xmlns:s="library://ns.adobe.com/flex/spark" 
        xmlns:mx="library://ns.adobe.com/flex/mx" viewSourceURL="srcview/index.html">
 
    <fx:Script>
        <![CDATA[
            private function list_labelFunc(item:Object):String {
                return item.name + " -- " + currFormatter.format(item.price);
            }
        ]]>
    </fx:Script>
 
    <fx:Declarations>
        <mx:CurrencyFormatter id="currFormatter" precision="2" />
    </fx:Declarations>
 
    <s:List id="list"
            labelFunction="list_labelFunc"
            horizontalCenter="0" verticalCenter="0">
        <s:dataProvider>
            <s:ArrayList>
                <fx:Object name="The"   price="0.23" />
                <fx:Object name="quick" price="1.03" />
                <fx:Object name="brown" price="0.98" />
                <fx:Object name="fox"   price="1.19" />
                <fx:Object name="jumps" price="0.28" />
                <fx:Object name="over"  price="0.42" />
                <fx:Object name="the"   price="0.09" />
                <fx:Object name="lazy"  price="0.81" />
                <fx:Object name="dog"   price="0.72" />
            </s:ArrayList>
        </s:dataProvider>
    </s:List>
 
</s:Application>

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View source is enabled in the following example.

Or, if you can use an XMLListCollection and the labelFunction property, as seen in the following example:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2009/03/08/setting-a-label-function-on-a-fxlist-control-in-flex-gumbo/ -->
<s:Application name="Spark_List_labelFunction_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009" 
        xmlns:s="library://ns.adobe.com/flex/spark" 
        xmlns:mx="library://ns.adobe.com/flex/mx">
 
    <fx:Script>
        <![CDATA[
            private function list_labelFunc(item:Object):String {
                return item.@name + " -- " + currFormatter.format(item.@price);
            }
        ]]>
    </fx:Script>
 
    <fx:Declarations>
        <mx:CurrencyFormatter id="currFormatter" precision="2" />
    </fx:Declarations>
 
    <s:List id="list"
            labelFunction="list_labelFunc"
            horizontalCenter="0" verticalCenter="0">
        <s:dataProvider>
            <s:XMLListCollection>
                <s:source>
                    <fx:XMLList>
                        <node name="The"   price="0.23" />
                        <node name="quick" price="1.03" />
                        <node name="brown" price="0.98" />
                        <node name="fox"   price="1.19" />
                        <node name="jumps" price="0.28" />
                        <node name="over"  price="0.42" />
                        <node name="the"   price="0.09" />
                        <node name="lazy"  price="0.81" />
                        <node name="dog"   price="0.72" />
                    </fx:XMLList>
                </s:source>
            </s:XMLListCollection>
        </s:dataProvider>
    </s:List>
 
</s:Application>

Due to popular demand, here is the “same” example in a more ActionScript friendly format:

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2009/03/08/setting-a-label-function-on-a-fxlist-control-in-flex-gumbo/ -->
<s:Application name="Spark_List_labelFunction_test"
        xmlns:fx="http://ns.adobe.com/mxml/2009" 
        xmlns:s="library://ns.adobe.com/flex/spark" 
        xmlns:mx="library://ns.adobe.com/flex/mx"
        initialize="init();">
 
    <fx:Script>
        <![CDATA[
            import mx.collections.ArrayList;
            import mx.formatters.CurrencyFormatter;
            import spark.components.List;
 
            protected const currFormatter:CurrencyFormatter = new CurrencyFormatter();
            protected var list:List;
 
            protected function init():void {
                currFormatter.precision = 2;
 
                var arr:Array = [];
                arr.push({name:"The", price:0.23});
                arr.push({name:"quick", price:1.03});
                arr.push({name:"brown", price:0.98});
                arr.push({name:"fox", price:1.19});
                arr.push({name:"jumps", price:0.28});
                arr.push({name:"over", price:0.42});
                arr.push({name:"the", price:0.09});
                arr.push({name:"lazy", price:0.81});
                arr.push({name:"dog", price:0.72});
 
                list = new List();
                list.labelFunction = list_labelFunc;
                list.dataProvider = new ArrayList(arr);
                list.horizontalCenter = 0;
                list.verticalCenter = 0;
                addElement(list);
            }
 
            private function list_labelFunc(item:Object):String {
                return item.name + " -- " + currFormatter.format(item.price);
            }
        ]]>
    </fx:Script>
 
</s:Application>

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.