<catch>

A <catch> element is an event handler.

Syntax

<catch cond="expression"
       count="integer"
       event="event1 ..." />

Attributes

cond

An expression which must evaluate to true after conversion to boolean in order for the event to be caught. Default value is true.

count

The occurrence of the event. The count allows you to handle different occurrences of the same event differently. Default value is 1.

event

The event or events to catch. A space-separated list of events may be specified, indicating that this element catches all the events named in the list. In such a case a separate event counter is maintained for each event. If the attribute is unspecified, all events are to be caught.

Children

<assign>, <audio>, <clear>, <disconnect>, <enumerate>, <exit>, <goto>, <if>, <log>, <prompt>, <reprompt>, <return>, <script>, <submit>, <throw>, <value>, and <var>.

Parents

<field>, <form>, <initial>, <menu>, <object>, <record>, <subdialog>, <transfer>, and <vxml>.

Variables

_event

The _event shadow variable identifies the event name that caused the exception.

_message

The user-defined message from the event.

Example

The following example illustrates catching an event.

<?xml version="1.0" encoding="UTF-8"?>
<vxml xmlns="http://www.w3.org/2001/vxml" 
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
  xsi:schemaLocation="http://www.w3.org/2001/vxml 
   http://www.w3.org/TR/voicexml20/vxml.xsd"
   version="2.0">
 <meta name="author" content="VoiceXML 2.0"/>
 <meta name="maintainer" content="productsupport@chant.net"/>
 <form id="launch_missiles">
  <field name="user_id" type="digits"> 
    <prompt>What is your username</prompt> 
  </field>
  <field name="password"> 
    <prompt>What is the code word?</prompt> 
    <grammar version="1.0" root="root">
     <rule id="root" scope="public">rutabaga</rule>
    </grammar>
   <help>It is the name of an obscure vegetable.</help> 
   <catch event="nomatch noinput" count="3"> 
     <prompt>Security violation!</prompt> 
     <submit next="http://www.example.com/apprehend_felon.vxml" namelist="user_id"/> 
   </catch> 
  </field> 
  </form>
</vxml>

Version Information

Supported in: VoiceXML 1.0, VoiceXML 2.0, and VoiceXML 2.1.