Flex Examples

It looks like I forgot to post this and I’ve had this as a draft for a week. I was looking at creating a regular expression for validating a UPS tracking number and/or InfoNotice number and decided to do a quick RegExp for validating a Canadian postal code instead. Fear not, my 3 loyal readers, I’ll post the other regular expressions later on.

Full code after the jump.

View MXML

<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2007/08/22/validating-data-using-regular-expressions/ -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white">

    <mx:Script>
        <![CDATA[
            private const postalcode_regex:RegExp = /^[A-Z][0-9][A-Z] [0-9][A-Z][0-9]$/i;

            private function validatePostalCode(evt:Event):void {
                if (postalcode_regex.test(ti1text)) {
                    ti1.errorString = null;
                } else {
                    ti1.errorString = postalCode_errorString;
                }
            }
        ]]>
    </mx:Script>

    <mx:String id="ti1text">{ti1.text}</mx:String>
    <mx:String id="postalCode_errorString">
        <![CDATA[Please enter a valid postal code in "L9L 9L9" format.]]>
    </mx:String>

    <mx:Form>
        <mx:FormItem label="Postal Code:" required="true">
            <mx:TextInput id="ti1"
                    maxChars="7"
                    restrict="A-Z 0-9"
                    change="validatePostalCode(event)" />
        </mx:FormItem>
    </mx:Form>

</mx:Application>

View source is enabled in the following example.

As a keen reader, Peter J. Farrell, points out below, my RegExp is fairly inaccurate. But as long as you’re OK with that fact that Canadian Postal Codes won’t really be validated properly, here’s another trick… It turns out you can use POSIX style named classes in ActionScript 3.0 regular expressions.

var str:String = "Victoria, BC, Canada V8P 3A8";
var pattern:RegExp = /(?P<postalCode>[[:alpha:]][[:digit:]][[:alpha:]] [[:digit:]][[:alpha:]][[:digit:]])/ig;

trace(str.replace(pattern, "(postal)"));

var result:Object = pattern.exec(str);
trace("postal code: " + result.postalCode);

And because I can never find some good RegExp POSIX information easily (without looking up the information in Ben Forta’s “Regular Expressions in 10 Minutes” book), here’s the list of POSIX Character Classes for future reference:

[[:alnum:]] - The set of alpha-numeric characters (same as [a-zA-Z0-9]).
[[:alpha:]] - The set of alphabetic characters (same as [a-zA-Z]).
[[:blank:]] - Tab and space (same as [\t ]).
[[:cntrl:]] - The control characters (ASCII 0-31, and 127).
[[:digit:]] - Decimal digits (same as [0-9]).
[[:graph:]] - All printable characters except space (same as [[:print:]], except does not include space).
[[:lower:]] - Lower case letters (same as [a-z]).
[[:print:]] - The “printable” characters.
[[:punct:]] - Punctuation. Any character not in [[:alnum:]] or [[:cntrl:]] range.
[[:space:]] - Whitespace characters (same as [\f\n\r\t\v ]).
[[:upper:]] - Upper case letters (same as [A-Z]).
[[:xdigit:]] - Hexidecimal digits (same as [a-fA-F0-9]).