There are many potential uses for this enhanced handler, including cross-attribute validation; enforcement of storage quotas when uploading files or creating content; CAPTCHA checks without needing to create datatypes; and much more.

Let's see how it works in practice. We use the custom edit handler with one additional method responsible for validation - “validateInput”. You can learn more about the custom edit handler here.

In its simplest form, it looks like this:

 
class MyCustomValidatorHandler extends eZContentObjectEditHandler
{
 
    function __construct()
    {
    }
 
 
    function fetchInput( $http, &$module, &$class, $object, &$version, $contentObjectAttributes, $editVersion, $editLanguage, $fromLanguage )
    {
    }
 
    static function storeActionList()
    {
    }
 
    function publish( $contentObjectID, $contentObjectVersion )
    {
    }
 
    function validateInput( $http, &$module, &$class, $object, &$version, $contentObjectAttributes, $editVersion, $editLanguage, $fromLanguage, $validationParameters )
    {
        $result = array( 'is_valid' => true, 'warnings' => array() );
        
        return $result;
    }
}

The handler must be placed in: extension/<extension-name>/content/<extension-name>handler.php. As always, the custom edit handler must be registered in a content.ini.append.php file as follows:

[EditSettings]
ExtensionDirectories[]= mycustomvalidator

Now a few notes about the validateInput method. The result is an array where one item is an is_valid boolean value, informing the system about the validation status; the second item is a warnings array where you can put relevant information about what went wrong.

Example:

 
    function validateInput( $http, &$module, &$class, $object, &$version, $contentObjectAttributes, $editVersion, $editLanguage, $fromLanguage, $validationParameters )
    {
        $result = array( 'is_valid' => true, 'warnings' => array() );
        $isValid =& $result['is_valid'];
        $warnings =& $result['warnings'];
 
        $phrase = $http->postVariable( 'ExampleTextField' );
 
        if( $phrase == '' )
        {
            $warnings[] = array( 'text' => ezi18n( 'extension/mycustomvalidator', 'The verification word is not valid' ) );
            $isValid = false;
        }
        return $result;
    }

When the validation fails (in this simple case, the user has left a required text field empty), the "The verification word is not valid" text is displayed to user.