public function init()
{
    /**
     * In this example the gateway is a Zend_Db_Table_Abstract subclass and returns Car objects on return.
     * The Car objects are subclasses of Zend_Db_Table_Row_Abstract.
     */
    $this->_gateway = new Car_Gateway();
    /**
     * Instantiate the special FormRedirector helper. Basicly this is the normal redirector with two extra methods.
     */
    $this->_redirector = $this->getHelper('FormRedirector');
}

public function editAction()
{
    /**
     * Fetch a form page instance. If it's available in storage, retrieve it. Otherwise make a new instance.
     * The default data source is $_POST
     */
    $form = Zend_Form_Factory::get($this->_formName, $this->_getParam('id'));
     
    if (!$form->fromStorage()) {
        /**
         * The page wasn't available in storage, so we're setting up a new one
         */

        /**
         * Colors our car can have.
         */
        $colors = array(
           'ff0000' => 'Red',
           '00ff00' => 'Green',
           '0000ff' => 'Blue'
        );
            
        /**
         * ID Element:
         * When using the formFied helper, it will output
         * <input type="hidden" name="id" value="" />
         */
        $form->addElement('id')
             ->addValidator(new Zend_Validate_Int()) // The ID needs to be an integer
             ->setAllowEmpty(true) // It can be empty, in case we want to add a new car to our DB
             ->addTypeHint(Zend_Form_Element_Hint_HTML::FORMAT, Zend_Form_Element_Hint_HTML::HIDDEN); //The type hint. The hint implies that if the field is outputted in HTML, it should be an 

        /**
         * Color field:
         * When using the formElement helper, it will output
         * <select name="color">
         *  <option value="ff0000">Red</option>
         *  <option value="00ff00">Green</option>
         *  <option value="0000ff">Blue</option>
         * </select>
         */
        $form->addElement('color', 'Zend_Form_Element_Set') //Specify the field class. It needs to be able to contain the options.
             ->addValidator(new Zend_Validate_InArray(array_flip($colors))) // The only valid values are those in the $colors array
             ->setOptions($colors) //Add the options to the set
             ->addTypeHint(Zend_Form_Element_Hint_HTML::FORMAT, Zend_Form_Element_Hint_HTML::SELECT); //And the type hint

        /** Doors Element */
        $form->addElement('doors')
             ->addValidator(new Zend_Validate_Int())
             ->addValidator(new Zend_Validate_GreaterThan(1))
             ->addTypeHint(Zend_Form_Element_Hint_HTML::FORMAT, Zend_Form_Element_Hint_HTML::TEXT);
                 
        /** Engine Element */
        $form->addElement('engine')
             ->addValidator(new Zend_Validate_Alnum())
             ->addTypeHint(Zend_Form_Element_Hint_HTML::FORMAT, Zend_Form_Element_Hint_HTML::TEXT);

        /**
         * Submit buttons.
         * All submit button names should be prefixed with a double underscore. This way, the submit action can be determined easiliy.
         * For your comofort, there are a few constants available for common submit buttons. 
         */
        $form->addElement(Zend_Form::SUBMIT_OK)
             ->setValue('OK'); //The text on the button
            
        $form->addElement(Zend_Form::SUBMIT_RESET)
             ->setValue('Reset');

        $form->addElement(Zend_Form::SUBMIT_CANCEL)
             ->setValue('Cancel');

        /**
         * If we're editing a entry from the DB, we want to load it once and set the default values for the form fields to the values in the entry.
         */
        if ($this->_getParam('id') != null) {
            /**
             * Fetch object from db
             */
            $car = $this->_gateway->getById($this->_getParam('id'));

            /**
             * And assign it's values to the form fields.
             */
            $form->setDefaultData($car->toArray());
        }
    }

    /**
     * Process the form page. If there hasn't been any submission process() will return false.
     * Otherwise all fields will receive their value which will be filtered and validated.
     */
    if ($form->process()) {
        /**
         * We want to know which button was pressed when submitting the form.
         * The process action was able to provide this information by using the double underscore prefix on submit button names.
         */
        switch ($form->getSubmitAction()) {
            /**
             * OK Button was pressed.
             */
            case Zend_Form::SUBMIT_OK:
                /**
                 * If all data is valid, forward to the save action to persist the data.
                 * Otherwise, redirect to re-display the form.
                 */
                if ($form->isValid()) {
                    $this->_redirector->formForward($form, 'save');
                } else {
                    $this->_redirector->formRedirect($form);
                }
                break;
            case Zend_Form::SUBMIT_RESET:
                $this->_redirector->formForward($form, 'reset');
                break;
            case Zend_Form::SUBMIT_CANCEL:
                $this->_redirector->formForward($form, 'cancel');
                break;
        }
    } else {
        /**
         * There was no submission, so assign the form page to the view so it can be rendered.
         */
        $this->view->form = $form;
    }
}

public function saveAction()
{
    /**
     * Fetch the form from storage
     */
    $form = Zend_Form_Factory::get($this->_formName, $this->_getParam(Zend_Form::FORM_IDENTIFIER_FIELD));
       
    /**
     * If the data isn't valid yet, go somewhere else
     */
    if (!$form->isValid()) {
        $this->_redirector->goto('index');
    }
      
    $id = (int)$form->id->value;
      
    /**
     * Collect the data
     */
    $data = array(
        'color' => $form->color->value,
        'doors' => $form->doors->value,
        'engine' => $form->engine->value
    );
        
    /**
     * Persist the data
     */
    if ($id > 0) {
        $car = $this->_gateway->find($id)->current();
    } else {
            $car = $this->_gateway->createRow();
    }
      
    $car->setFromArray($data);
    $car->save();

    /*
     * Remove the form page from storage, we don't need it anymore
     */
    Zend_Form_Factory::remove($this->_formName, $this->_getParam(Zend_Form::FORM_IDENTIFIER_FIELD));
        
    /*
     * Redirect to the view page to have a look at our fresh entry.
     */
    $this->_redirector->goto('view', null, null, array('id' => $car->id));
}

// The lazy man's way: generate a complete form
echo $this->makeForm($this->form);

// Or for more flexibility, use the formField helper
echo $this->formField($this->form->id);
echo $this->formField($this->form->color);
echo $this->formField($this->form->doors);