Question

I have a custom component written in ActionScript. It has constructor which is expecting some arguments.

I want to include that custom component in mxml like this,

Main.mxml

...
<custom:CustomActionScriptComponent/>  // Error line ..
..

But, it shows me an error saying

Error 1136: Incorrect number of arguments.  Expected 1.

How to pass parameter in MXML file, to that custom ActionScript component?

Answer 1

As tags, MXML does not support class constructors.

Per your ActionScript class, you could allow default initialization of the parameter:

    public function CustomActionScriptComponent(parameter:Object=null)
    {
        super();
    }

Then implement a creation complete event handler in your MXML:

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
               xmlns:s="library://ns.adobe.com/flex/spark"
               xmlns:mx="library://ns.adobe.com/flex/mx"
               creationComplete="creationCompleteHandler(event)">

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

            protected function creationCompleteHandler(event:FlexEvent):void
            {
                customActionScriptComponent.parameter = {};
            }
        ]]>
    </fx:Script>

    <custom:CustomActionScriptComponent id="customActionScriptComponent" />

</s:Application>