Help with Zend Framework getAction method

I am new to MVC and Zend, so I have little idea what I am doing at the moment, but here is my question.

The following code is my get method for an API I am attempting to build in order to learn both. It works as is, but given the sparsity of code I have seen in example methods, and the fact that Zend seems to do a lot for you, is there a better way of doing this? The code is something I cobbled together because the tutorial that I was walking through forgot to add the get method code.

public function getAction()
{
    // action body
    // Is there a better way to get the id from the URL?
    $this->_getAllParams();
    $request = $this->_request->getParams();

    if (array_key_exists($request['id'], $this->_todo)){
        $return[] = array($request['id'] => $this->_todo[$request['id']]);
    }else{
        // error code here or call some error method?
        // do I do error coding here or send a message to some handler/helper?
    }
    echo Zend_Json::encode($return);
}

Essentially this will take a URL and pass json encode information that is currently stored in an array.

i.e.

http://restapi.local/api/1

displays:

[{"1":"Buy milk"}]

EDIT:

The routing apparently takes place in the bootstrap:

class Bootstrap extends Zend_Application_Bootstrap_Bootstrap
{
    public function _initRoutes()
    {
        $front = Zend_Controller_Front::getInstance();
        $router = $front->getRouter();
        $restRoute = new Zend_Rest_Route($front);
        $router->addRoute('default', $restRoute);
    }

}

And below is the full ApiController.php:

class ApiController extends Zend_Controller_Action
{
    public function init()
    {
        /* Initialize action controller here */
        $this->_helper->viewRenderer->setNoRender(true);
        $this->_todo = array (
                    "1" => "Buy milk",
                    "2" => "Pour glass of milk",
                     "3" => "Eat cookies"
        );
    }

    public function indexAction()
    {
        // action body
        echo Zend_Json::encode($this->_todo);
    }

    public function getAction()
    {
        // action body
        $this->_getAllParams();
        $request = $this->_request->getParams();
        if (array_key_exists($request['id'], $this->_todo)){
            $return[] = array($request['id'] => $this->_todo[$request['id']]);
        }
        echo Zend_Json::encode($return);
    }

    public function postAction()
    {
        // action body
        $item = $this->_request->getPost('item');

        $this->_todo[count($this->_todo) + 1] = $item;

        echo Zend_Json::encode($this->_todo);
    }

    public function putAction()
    {
        // action body
    }

    public function deleteAction()
    {
        // action body
    }
}