Zend框架ACL没有提取＆＃39;角色＆＃39;数据库中的列

Question

我目前正在开展一个需要ACL的项目，问题是＆＃39;角色＆＃39;列未被识别。我已经在“用户”中预定义了所有角色。表

AuthPlugin文件

    $auth = Zend_Auth::getInstance();

    // If user is not logged in and is not requesting login page
    // - redirect to login page.
    if (!$auth->hasIdentity()
    && $request->getControllerName() != $loginController
    && $request->getActionName()     != $loginAction) {

        $redirector = Zend_Controller_Action_HelperBroker::getStaticHelper('Redirector');
        $redirector->gotoSimpleAndExit($loginAction, $loginController);
    }

    // User is logged in or on login page.

    if ($auth->hasIdentity()) {
         $registry = Zend_Registry::getInstance();
        $acl = $registry->get('acl');
        $identity = $auth->getIdentity();
        $isAllowed = $acl->isAllowed($identity->role,
        $request->getControllerName(),
        $request->getActionName());
        if (!$isAllowed) {
        $redirector = Zend_Controller_Action_HelperBroker::getStaticHelper('Redirector');
        $redirector->gotoUrlAndExit('/');
    }
    }
    }
    }

ACL配置

<?php
$acl = new Zend_Acl();

$roles  = array('Administrator', 'User');
$controllers = array('cart', 'index', 'user', 'purchase');
    foreach ($roles as $role) {
    $acl->addRole(new Zend_Acl_Role($role));
}
foreach ($controllers as $controller) {
    $acl->add(new Zend_Acl_Resource($controller));
}
$acl->allow('Administrator'); 
$acl->allow('User');
$acl->deny('User', 'Administrator');

$registry = Zend_Registry::getInstance();
$registry->set('acl', $acl);

控制器

  public function indexAction()
{
    $form = new Application_Form_Login();
    $request = $this->getRequest();
    if ($request->isPost()) {
        if ($form->isValid($request->getPost())) {
            if ($this->_process($form->getValues())) {
                $this->_helper->redirector('index', 'index');
            }
        }
    }
    $this->view->form = $form;
}

protected function _process($values)
{
    $adapter = $this->_getAuthAdapter();
    $adapter->setIdentity($values['username']);
    $adapter->setCredential($values['password']);

    $auth = Zend_Auth::getInstance();
    $result = $auth->authenticate($adapter);
    if ($result->isValid()) {
        $user = $adapter->getResultRowObject();
        $auth->getStorage()->write($user);
        return true;
    }
    return false;
}

protected function _getAuthAdapter()
{   
    $dbAdapter = Zend_Db_Table::getDefaultAdapter();
    $authAdapter = new Zend_Auth_Adapter_DbTable($dbAdapter);

    $authAdapter->setTableName('users')
                ->setIdentityColumn('username')
                ->setIdentity($username)
                ->setCredentialColumn('password')
                ->setCredentialTreatment('MD5(?)');
    $auth = Zend_Auth::getInstance();
    $result = $auth->authenticate($authAdapter);
    if ($result->isValid()) {
        $data = $authAdapter->getResultRowObject(null, 'password'); // without password
        $auth->getStorage()->write($data);
    return $authAdapter;
}

当我尝试登录时，我收到一条错误消息

Message: A value for the identity was not provided prior to authentication with Zend_Auth_Adapter_DbTable.

请告诉我一种可以获得“角色”的方法。来自用户表。