Magento 图片上传表单字段

我跟着这个链接 http://www.magentocommerce.com/wiki/5_-_modules_and_development/admin/how_to_create_pdf_upload_in_backend_for_own_module使图像上传在我的 Magento 模块中工作，但代码所做的最重要的事情是通过 POST 传递选定的文件名：$_FILES每当我添加时数组都是空的image or file fields.

这是我的代码：

<?php
class Moo_News_Block_Adminhtml_News_Edit_Tab_Form extends Mage_Adminhtml_Block_Widget_Form
{
    protected function _prepareForm()
    {
        $form = new Varien_Data_Form();
        $this->setForm($form);
        $fieldset = $form->addFieldset('news_form', array('legend' => Mage::helper('news')->__('Item information')));

        $fieldset->addField('title', 'text', array(
            'label'     => Mage::helper('news')->__('Title'),
            'class'     => 'required-entry',
            'required'  => true,
            'name'      => 'title',
        ));

        $fieldset->addField('published', 'select', array(
            'label'     => Mage::helper('news')->__('Published'),
            'name'      => 'published',
            'required'  => true,
            'values'    => array(
                array(
                    'value'     => 1,
                    'label'     => Mage::helper('news')->__('Yes'),
                ),

                array(
                    'value'     => 0,
                    'label'     => Mage::helper('news')->__('No'),
                ),
            ),
        ));

        $fieldset->addField('short_description', 'editor', array(
            'name'      => 'short_description',
            'label'     => Mage::helper('news')->__('Short Description'),
            'title'     => Mage::helper('news')->__('Short Description'),
            'style'     => 'width:98%; height:200px;',
            'wysiwyg'   => false,
            'required'  => true,
        ));

        $fieldset->addField('body', 'editor', array(
            'name'      => 'body',
            'label'     => Mage::helper('news')->__('Body'),
            'title'     => Mage::helper('news')->__('Body'),
            'style'     => 'width:98%; height:400px;',
            'wysiwyg'   => false,
            'required'  => true,
        ));


        $fieldset->addField('image', 'file', array(
            'label'     => Mage::helper('news')->__('Image'),
            'required'  => false,
            'name'      => 'image',
        ));

        if ( Mage::getSingleton('adminhtml/session')->getNewsData() )
        {
            $form->setValues(Mage::getSingleton('adminhtml/session')->getNewsData());
            Mage::getSingleton('adminhtml/session')->setNewsData(null);
        } elseif ( Mage::registry('news_data') ) {
            $form->setValues(Mage::registry('news_data')->getData());
        }

        return parent::_prepareForm();
    }
}

和控制器代码：

<?php

/**
 *
 *
 */

class Moo_News_Adminhtml_NewsController extends Mage_Adminhtml_Controller_Action
{

    protected function _initAction()
    {
        $this->loadLayout()
            ->_setActiveMenu('news/items')
            ->_addBreadcrumb(Mage::helper('adminhtml')->__('Items Manager'), Mage::helper('adminhtml')->__('Item Manager'));
        return $this;
    }

    public function indexAction() {
        $this->_initAction();
        $this->_addContent($this->getLayout()->createBlock('news/adminhtml_news'));
        $this->renderLayout();
    }

    public function editAction()
    {
        $newsId     = $this->getRequest()->getParam('id');
        $newsModel  = Mage::getModel('news/post')->load($newsId);

        if ($newsModel->getId() || $newsId == 0) {

            Mage::register('news_data', $newsModel);

            $this->loadLayout();
            $this->_setActiveMenu('news/items');

            $this->_addBreadcrumb(Mage::helper('adminhtml')->__('Item Manager'), Mage::helper('adminhtml')->__('Item Manager'));
            $this->_addBreadcrumb(Mage::helper('adminhtml')->__('Item News'), Mage::helper('adminhtml')->__('Item News'));

            $this->getLayout()->getBlock('head')->setCanLoadExtJs(true);

            $this->_addContent($this->getLayout()->createBlock('news/adminhtml_news_edit'))
                 ->_addLeft($this->getLayout()->createBlock('news/adminhtml_news_edit_tabs'));

            $this->renderLayout();
        } else {
            Mage::getSingleton('adminhtml/session')->addError(Mage::helper('news')->__('Item does not exist'));
            $this->_redirect('*/*/');
        }
    }

    public function newAction()
    {
        $this->_forward('edit');
    }

    public function saveAction()
    {
        if ( $this->getRequest()->getPost() ) {
            try {
                $postData = $this->getRequest()->getPost();
                $newsModel = Mage::getModel('news/post');

                $imgFilename = NULL;

                //if (isset($postData['image']) && $postData['image'] != '') {
                //if (isset($_FILES['image']['name']) && $_FILES['image']['name'] != '') {
                if (false) {
                    try {
                        $uploader = new Varien_File_Uploader('image');

                        $uploader->setAllowedExtensions(array('jpg','jpeg','gif','png'));
                        $uploader->setAllowRenameFiles(false);
                        $uploader->setFilesDispersion(false);

                        // Set media as the upload dir
                        $media_path  = Mage::getBaseDir('media');

                        $imgFilename = $media_path . $postData['image'];

                        while (file_exists($filename)) {
                            $pieces = array();

                            $res = preg_match('/^(.+)_(\d+)$/', $filename, $pieces);

                            if (!$res) {
                                $filename .= '_1';
                            } else {
                                $filename .= '_' . strval(intval($pieces[2]) + 1);
                            }
                        }

                        // Upload the image
                        $uploader->save($media_path, $postData['image']);
                    }
                    catch (Exception $e) {
                        Mage::log($e);
                        $this->redirectError(502);
                    }
                } else {
                    if(isset($postData['image']['delete']) && $postData['image']['delete'] == 1) {
                        $imgFilename = NULL;
                    }
                }

                if(isset($imgFilename))
                    $newsModel->setImage($imgFilename);

                $newsModel->setId($this->getRequest()->getParam('id'))
                    ->setTitle($postData['title'])
                    ->setBody($postData['body'])
                    ->setShortDescription($postData['short_description'])
                    ->save();

                Mage::getSingleton('adminhtml/session')->addSuccess(Mage::helper('adminhtml')->__('Item was successfully saved'));
                Mage::getSingleton('adminhtml/session')->setNewsData(false);

                $this->_redirect('*/*/');
                return;
            } catch (Exception $e) {
                Mage::getSingleton('adminhtml/session')->addError($e->getMessage());
                Mage::getSingleton('adminhtml/session')->setNewsData($this->getRequest()->getPost());
                $this->_redirect('*/*/edit', array('id' => $this->getRequest()->getParam('id')));
                return;
            }
        }
        $this->_redirect('*/*/');
    }

    public function deleteAction()
    {
        if( $this->getRequest()->getParam('id') > 0 ) {
            try {
                $newsModel = Mage::getModel('news/post');

                $newsModel->setId($this->getRequest()->getParam('id'))
                    ->delete();

                Mage::getSingleton('adminhtml/session')->addSuccess(Mage::helper('adminhtml')->__('Item was successfully deleted'));
                $this->_redirect('*/*/');
            } catch (Exception $e) {
                Mage::getSingleton('adminhtml/session')->addError($e->getMessage());
                $this->_redirect('*/*/edit', array('id' => $this->getRequest()->getParam('id')));
            }
        }
        $this->_redirect('*/*/');
    }
    /**
     * Product grid for AJAX request.
     * Sort and filter result for example.
     */
    public function gridAction()
    {
        $this->loadLayout();
        $this->getResponse()->setBody(
               $this->getLayout()->createBlock('importedit/adminhtml_news_grid')->toHtml()
        );
    }
}

所以，问题是：我应该如何以正确的方式做到这一点？

诀窍是更改默认的表单创建代码

$form = new Varien_Data_Form(array(
    'id' => 'edit_form',
    'action' => $this->getUrl('*/*/save', array('id' => $this->getRequest()->getParam('id'))),
    'method' => 'post',
));

to

$form = new Varien_Data_Form(array(
    'id' => 'edit_form',
    'action' => $this->getUrl('*/*/save', array('id' => $this->getRequest()->getParam('id'))),
    'method' => 'post',
    'enctype' => 'multipart/form-data'
));

不在我提供的代码内，而是在该部分的调用者内（..._Adminhtml_News_Edit_Form代替..._Adminhtml_News_Edit_Tab_Form).