StringValidator

Package	mx.validators
Class	public class StringValidator
Inheritance	StringValidator Validator EventDispatcher Object

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

The StringValidator class validates that the length of a String is within a specified range.

MXML Syntax expanded

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The <mx:StringValidator> tag inherits all of the tag attributes of its superclass, and add the following tag attributes:

  <mx:StringValidator
    maxLength="NaN" 
    minLength="NaN" 
    tooLongError="This string is longer than the maximum allowed length. This must be less than {0} characters long." 
    tooShortError="This string is shorter than the minimum allowed length. This must be at least {0} characters long." 
  />

View the examples

More examples

Enabling and disabling a validator
Validating strings

Learn more

Validating data
About the source and property properties
About triggering validation
Triggering validation by using events
Triggering validation programmatically
Validating required fields
General guidelines for validation
Working with validation errors
Working with validation events

Public Properties

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	Property		Defined By
		constructor : Object A reference to the class object or constructor function for a given object instance.	Object
		enabled : Boolean Setting this value to false will stop the validator from performing validation.	Validator
		listener : Object Specifies the validation listener.	Validator
		maxLength : Object Maximum length for a valid String.	StringValidator
		minLength : Object Minimum length for a valid String.	StringValidator
		property : String A String specifying the name of the property of the source object that contains the value to validate.	Validator
		required : Boolean = true If true, specifies that a missing or empty value causes a validation error.	Validator
		requiredFieldError : String Error message when a value is missing and the required property is true.	Validator
		source : Object Specifies the object containing the property to validate.	Validator
		tooLongError : String Error message when the String is longer than the maxLength property.	StringValidator
		tooShortError : String Error message when the string is shorter than the minLength property.	StringValidator
		trigger : IEventDispatcher Specifies the component generating the event that triggers the validator.	Validator
		triggerEvent : String Specifies the event that triggers the validation.	Validator

Protected Properties

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	Property		Defined By
		actualListeners : Array [read-only] Contains an Array of listener objects, if any, or the source object.	Validator
		actualTrigger : IEventDispatcher [read-only] Contains the trigger object, if any, or the source object.	Validator
		resourceManager : IResourceManager [read-only] A reference to the object which manages all of the application's localized resources.	Validator
		subFields : Array An Array of Strings containing the names for the properties contained in the value Object passed to the validate() method.	Validator

Public Methods

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	Method		Defined By
		StringValidator() Constructor.	StringValidator
		addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void Registers an event listener object with an EventDispatcher object so that the listener receives notification of an event.	EventDispatcher
		dispatchEvent(event:Event):Boolean Dispatches an event into the event flow.	EventDispatcher
		hasEventListener(type:String):Boolean Checks whether the EventDispatcher object has any listeners registered for a specific type of event.	EventDispatcher
		hasOwnProperty(name:String):Boolean Indicates whether an object has a specified property defined.	Object
		initialized(document:Object, id:String):void Called automatically by the MXML compiler when the Validator is created using an MXML tag.	Validator
		isPrototypeOf(theClass:Object):Boolean Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.	Object
		propertyIsEnumerable(name:String):Boolean Indicates whether the specified property exists and is enumerable.	Object
		removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void Removes a listener from the EventDispatcher object.	EventDispatcher
		setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void Sets the availability of a dynamic property for loop operations.	Object
		toLocaleString():String Returns the string representation of this object, formatted according to locale-specific conventions.	Object
		toString():String Returns the string representation of the specified object.	Object
		validate(value:Object = null, suppressEvents:Boolean = false):ValidationResultEvent Performs validation and optionally notifies the listeners of the result.	Validator
		validateAll(validators:Array):Array [static] Invokes all the validators in the validators Array.	Validator
		validateString(validator:StringValidator, value:Object, baseField:String = null):Array [static] Convenience method for calling a validator.	StringValidator
		valueOf():Object Returns the primitive value of the specified object.	Object
		willTrigger(type:String):Boolean Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type.	EventDispatcher

Protected Methods

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	Method		Defined By
		addListenerHandler():void Sets up all of the listeners for the valid and invalid events dispatched from the validator.	Validator
		doValidation(value:Object):Array [override] Override of the base class doValidation() method to validate a String.	StringValidator
		getValueFromSource():Object Returns the Object to validate.	Validator
		handleResults(errorResults:Array):ValidationResultEvent Returns a ValidationResultEvent from the Array of error results.	Validator
		isRealValue(value:Object):Boolean Returns true if value is not null.	Validator
		removeListenerHandler():void Disconnects all of the listeners for the valid and invalid events dispatched from the validator.	Validator
		resourcesChanged():void This method is called when a Validator is constructed, and again whenever the ResourceManager dispatches a "change" Event to indicate that the localized resources have changed in some way.	Validator

Events

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	Summary	Defined By
activate	[broadcast event] Dispatched when the Flash Player or AIR application gains operating system focus and becomes active.	EventDispatcher
deactivate	[broadcast event] Dispatched when the Flash Player or AIR application operating loses system focus and is becoming inactive.	EventDispatcher
invalid	Dispatched when validation fails.	Validator
valid	Dispatched when validation succeeds.	Validator

Protected Constants

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	Constant		Defined By

Property Detail

maxLength

property

maxLength:Object

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Maximum length for a valid String. A value of NaN means this property is ignored.

The default value is NaN.

Implementation
public function get maxLength():Object
public function set maxLength(value:Object):void

minLength

property

minLength:Object

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Minimum length for a valid String. A value of NaN means this property is ignored.

The default value is NaN.

Implementation
public function get minLength():Object
public function set minLength(value:Object):void

tooLongError

property

tooLongError:String

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Error message when the String is longer than the maxLength property.

The default value is "This string is longer than the maximum allowed length. This must be less than {0} characters long.".

Implementation
public function get tooLongError():String
public function set tooLongError(value:String):void

tooShortError

property

tooShortError:String

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Error message when the string is shorter than the minLength property.

The default value is "This string is shorter than the minimum allowed length. This must be at least {0} characters long.".

Implementation
public function get tooShortError():String
public function set tooShortError(value:String):void

Constructor Detail

()

Constructor

public function StringValidator()

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Constructor.

Method Detail

doValidation

()

method

override protected function doValidation(value:Object):Array

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Override of the base class doValidation() method to validate a String.

You do not call this method directly; Flex calls it as part of performing a validation. If you create a custom Validator class, you must implement this method.

Parameters

value:Object — Object to validate.

Returns

Array — An Array of ValidationResult objects, with one ValidationResult object for each field examined by the validator.

validateString

()

method

public static function validateString(validator:StringValidator, value:Object, baseField:String = null):Array

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

Convenience method for calling a validator. Each of the standard Flex validators has a similar convenience method.

Parameters

	`validator:StringValidator` — The StringValidator instance.

	`value:Object` — A field to validate.

	`baseField:String` (default = `null`) — Text representation of the subfield specified in the `value` parameter. For example, if the `value` parameter specifies value.mystring, the `baseField` value is `"mystring"`.

Returns

Array — An Array of ValidationResult objects, with one ValidationResult object for each field examined by the validator.

Related API Elements

mx.validators.ValidationResult

Examples How to use this example

StringValidatorExample.mxml

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<?xml version="1.0" encoding="utf-8"?>
<!-- Simple example to demonstrate StringValidator. -->
<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">

    <fx:Script>
        import mx.controls.Alert;
    </fx:Script>

    <fx:Declarations>
        <mx:StringValidator source="{fname}" property="text" 
                tooShortError="This string is shorter than the minimum allowed length of 4. " 
                tooLongError="This string is longer than the maximum allowed length of 20." 
                minLength="4" maxLength="20"  
                trigger="{myButton}" triggerEvent="click" 
                valid="Alert.show('Validation Succeeded!');"
                invalid="Alert.show('Validation Failed!');"/>
    </fx:Declarations>

    <s:Panel title="StringValidator Example"
            width="75%" height="75%"
            horizontalCenter="0" verticalCenter="0">
        <mx:Form left="10" right="10" top="10" bottom="10">
                <mx:FormItem label="Enter a name between 4 and 20 characters: ">
                    <s:TextInput id="fname" width="100%"/>
                </mx:FormItem>
                <mx:FormItem >
                    <s:Button id="myButton" label="Validate" />
                </mx:FormItem>
        </mx:Form>
    </s:Panel>

</s:Application>

StringValidator - AS3 Flex

Classes x

maxLength

minLength

tooLongError

tooShortError