Macromedia flex 2 Manual

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" ?>
<!-- validators/MainNameValidator.mxml -->
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" 
    xmlns:MyComp="myValidators.*"> 

    <mx:Model id="person">
        <name>
          <custName>
             <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 

TextInput

 control.