User Guide

222 Creating Custom Validators

Example: Validating multiple fields

A validator can validate more than one field at a time. For example, you could create a custom

validator called NameValidator to validate three input controls that represent a person’s first,

middle, and last names.

To create a validator that examines multiple fields, you can either define properties on the

validator that let you specify the multiple input fields, as does the Flex DateValidator class

class, or you can require that the single item passed to the validator includes all of the fields to

be validated.

In the following example, you use a NameValidator that validates an item that contains three

fields named

first, middle, and last:

<?xml version="1.0" ?>

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"

xmlns:MyComp="myValidators.*">

<mx:Model id="person">

<name>

<first>{firstInput.text}</first>

<middle>{middleInput.text}</middle>

<last>{lastInput.text}</last>

</custName>

</name>

</mx:Model>

<mx:TextInput id="firstInput"/>

<mx:TextInput id="middleInput"/>

<mx:TextInput id="lastInput"/>

<MyComp:NameValidator id="nameVal"

source="{person}" property="custName"

listener="{firstInput}"/>

<mx:Button label="Validate" click="nameVal.validate();"/>

</mx:Application>

This validator examines three input fields. You specify firstInput as the validation listener.

Therefore, when a validation error occurs, Flex shows a validation error message on the first

Te xt In pu t control.