Switch context with ZF - JSON/HTML

gistfile1.php

<?php
class Bruegelbe_InfocusController extends Herder_Controller_Action
{
    public function init() {
        $context = $this->_helper->contextSwitch();
        $context->addActionContext('contentItems', array('json'))
                ->initContext();
    }
     public function contentItemsAction() {
        $tables = Bruegel_Model_Infocus::getTables();
        $table = $this->_getParam('table');
        
        $class = $tables[$table];
        $model = new $class();
        
        $data = null; 
        if(isset($model) && is_object($model)) {
            if($table =='tx_bruegel_people') {
                $order ='name';
            } else {
                $order ='title';
            }
            
            $data = $model->getAll(array(), null, $order);
        }
        
        $this->view->data = Bruegel_Model_Infocus::buildArray($data);
        if($this->_request->isXmlHttpRequest()) {
               $this->_helper->contextSwitch()->initContext('json');
        }
    }
}