If you've ever used the `restrict` property on the Flex TextInput control - you've probably wished that it was more than just a string property. While it does allow you to specify characters, and character ranges like A-Z or 0-9, it isn't nearly as convenient or as robust as a regex.

Here is a simple subclass of TextInput that implements the same functionality as `restrict` but using a regular expression.

View the sample application ...and the source code.

 
package com.appdivision.components
{
    import flash.events.TextEvent;
    import mx.controls.TextInput;
 
    public class RegexTextInput extends TextInput
    {
 
        private var _regex:RegExp;
 
        public function RegexTextInput()
        {
            super();
        }
 
        [Bindable]
        public function set regex(value:RegExp):void
        {
            if (value != _regex)
            {
                _regex = value;
            }
        }
 
        public function get regex():RegExp
        {
            return _regex;
        }
 
        override protected function childrenCreated():void
        {
            super.childrenCreated()
 
            addEventListener(TextEvent.TEXT_INPUT, handleTextInput);
        }
 
        public function handleTextInput(event:TextEvent):void
        {
            if (regex)
            {
                 // What the text will be if this input is allowed to happen
                 var textToBe:String = "";
                // Accomidate for a selection
                if (selectionBeginIndex > 0)
                {
                    textToBe += text.substr(0, selectionBeginIndex)
                }
                textToBe += event.text;
                if (selectionEndIndex > 0)
                {
                    textToBe += text.substr(selectionEndIndex, text.length - selectionEndIndex);
                }
                var match:Object = regex.exec(textToBe);
                if (!match || match[0] != textToBe)
                {
                    // The textToBe didn't match the expression... stop the event
                    event.preventDefault();
                }
            }
        }
    }
}
 

Enjoy.

Things are getting pretty exciting here at MLB.com as we are nearing the end of development of the new MLB.TV Media Player. It is 4:30 in the morning and all the devs are here in the MLB offices in Chelsea to launch the PUBLIC BETA for the first game of the World Baseball Classic.

That's it folks! The player is officially in the wild! You can check out the launch page here. If you're up at this crazy hour like we are, the link to the opening Japan vs. China game is at the bottom.