conditional-field.inc.php

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<?php
class ConditionalField extends CollectionField
{
    private $activeOn; 
    protected static $jsDrawn = false; //< If the JavaScript has been drawn yet or not

    public function __construct($name, Form &$parentForm, array $attribs = array()) 
    {
        if(array_key_exists('fields', $attribs) === false)
            throw new Exception("key 'fields' must exist in attribs array");

        if(count($attribs['fields']) != 1)
            throw new Exception("only one field can be added to a ConditionalField");

        array_unshift($attribs['fields'], array('CheckboxField', "${name}_box", $attribs));

        # Set a "normal" default
        $this->activeOn = true;
        parent::__construct($name, $parentForm, $attribs);
    }


    public function __set($name, $value)
    {
        if($name == 'activeOn')
            $this->activeOn = $value;
        else
            parent::__set($name, $value);
    }
            
    
    public function drawInput()
    {
        $subFieldArr = $this->subFieldsToJsArray();
        $this->fields[0]->onchange = "changeCondState(this, $subFieldArr, " . ($this->activeOn ? 'true' : 'false') . ');';
        parent::drawInput();
    }
    
    public function getJs()
    {
        if(self::$jsDrawn)
            return null;

        self::$jsDrawn = true;

        return <<<EOJAVASCRIPT
        function changeCondState(chkbox, fields, activeOn)
        {
            var newDisabled;

            if(chkbox.checked == activeOn)
                newDisabled = false;
            else
                newDisabled = true;


            for(var i = 0; i < fields.length; i++)
            {
                var fieldObj = document.getElementById(fields[i]);
                fieldObj.disabled = newDisabled;
            }
        }
EOJAVASCRIPT;
    }

    
    protected function subFieldsToJsArray()
    {
        $fieldNames = array();
        foreach($this->fields as $field)
        {
            $fieldNames[] = $field->name;
        }
        array_shift($fieldNames); # don't include the checkbox (which should be the first field)

        return 'new Array(\'' . implode('\', \'', $fieldNames) . '\')';
    }
}
?>

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