Yii user-> isGuest返回false，但在打印到屏幕时显示为guest

I have a really odd problem showing up the beginnings of my authentication for a small Yii app I am building. I have an "account" table set up in my database that is set up with a different primary key than an AUTO_INCREMENT id.

At this point, I am simply using the tutorial-level UserIdentity file supplied from here: http://www.yiiframework.com/doc/guide/1.1/en/topics.auth

I'm grabbing the login data from my form using POST and checking it in the controller as necessary.

public function actionLogin()
{   
    if( isset($_POST["username"]) && isset($_POST["password"]) ){
        $identity = new UserIdentity($_POST["username"], $_POST["password"]);

        if($identity->authenticate()){
            $success = Yii::app()->user->login($identity);
            $this->redirect(array('site/index'));

        } else {
            echo print_r($identity->errorMessage);
        }
    }

    $this->render('login');
}

authenticate() returns true when entering proper credentials, and false when I put nonsense in the fields, as it should. After the authentication, it redirects to the index/home page.

Now, this is the part that doesn't make sense: In the index page, I am checking the state of my user by dumping the getId() method (which I have overridden), as well as checking a state variable I have set. In addition, when I

echo Yii::app()->user->isGuest;

to the screen, it returns false. Wow, great -- the login should be successful. WRONG.

When I do a dump of the user property of the app,

print_r(Yii::app()->user);

It shows the CWebUser being empty and as a guest. It's driving me insane.

CWebUser Object ( 
[allowAutoLogin] => 1 
[guestName] => Guest 
[loginUrl] => Array ( 
    [0] => /site/login ) 
[identityCookie] => 
[authTimeout] => 
[autoRenewCookie] => 
[autoUpdateFlash] => 1 
[loginRequiredAjaxResponse] => 
[_keyPrefix:CWebUser:private] => ccd216fa11757a8e75e940c97a24ee44                 
[_access:CWebUser:private] => Array ( ) 
    [behaviors] => Array ( ) 
[_initialized:CApplicationComponent:private] => 1 
[_e:CComponent:private] => 
[_m:CComponent:private] => )

Any insight? Is there an issue with my configuration or something I may have missed?

EDIT: UserIdentity Class

class UserIdentity extends CUserIdentity

{ private $_id;

public function authenticate(){
    $record = Account::model()->findByAttributes(array('username'=>$this->username));

    if($record === NULL){
        $this->errorCode = self::ERROR_USERNAME_INVALID;

    } else if($record->password !== crypt($this->password, $record->password)){
        $this->errorCode = self::ERROR_PASSWORD_INVALID;

    } else {
        $this->_id = $record->id;
        $this->setState('username', $this->username);
        $this->setState('friend_code', $record->friend_code);
        $this->errorCode = self::ERROR_NONE;
    }

    return !$this->errorCode;
}

public function getId(){
    return $this->_id;
}

EDIT: I've checked some other things over, and updated my UserIdentity Class. I can now also get $_id from Yii::app()->user->id OR Yii::app()->getId().

I've found that Yii::app()->user->identityCookie doesn't exist, and I don't see any cookies other than PHPSESHID in my browser resources. Is this normal?

EDIT EDIT: So after seeing the first answer, I decided to take a look deeper into the CWebUser class. It looks like the only piece of the puzzle that may not be working is this line here.

$this->changeIdentity($id,$identity->getName(),$states);
// what this method actually looks like:
protected function changeIdentity($id,$name,$states)
{
Yii::app()->getSession()->regenerateID(true);
$this->setId($id);
$this->setName($name);
$this->loadIdentityStates($states);
}

I think I found the problem. Look at the following code from CWebUser:

public function getIsGuest()
{
    return $this->getState('__id')===null;
}

It retrieves the $id-attribute from your UserIdentity and bypasses the getId()-method.

So to fix this, you should either scrap using your $_friend_code-attribute and only use $this->id, or add the following line in your authenticate()-method in the second else-block.

// some code before this
else {
    $this->_friend_code = $record->friend_code;
    $this->id = $record->friend_code;
    $this->setState('username', $this->username);
    $this->setState('test', "test");
    $this->errorCode = self::ERROR_NONE;
}

I recommend the first choice, as it tends to be the normal way to do things. But it's up for you to decide.

Hope this helped!

EDIT: another option would be to override the getIsGuest()-method in CWebUser of course.