无效的yii关系有多个

我正在用Yii构建一个简单的投票应用程序

我有以下表格：

create table poll (
    id integer not null auto_increment,
    title varchar(255) not null,
    views integer not null default 0,
    created_at timestamp not null default NOW(),
    PRIMARY KEY(id)
);

create table choice (
    poll_id integer not null,
    choice varchar(200) not null,
    votes integer not null default 0
);

我有一个投票的ActiveRecord，定义为：

class Poll extends CActiveRecord
{
...
    public function relations()
    {
        return array(
            'choices'=>array(self::HAS_MANY, 'Choice', 'poll_id'),
        );
    }
...
}

但是，当我使用以下代码时：

$p = Poll::model()->findByPk($id)->with('choices')->findAll();

它给了我回溯：

Invalid argument supplied for foreach()

#0  
+  /home/william/scm/bmbraga/clickpoll/yii/framework/db/ar/CActiveFinder.php(791): CJoinElement->populateRecord(CJoinQuery, array("1", "0", "", "2011-02-28 13:11:41", ...))
#1  
+  /home/william/scm/bmbraga/clickpoll/yii/framework/db/ar/CActiveFinder.php(736): CJoinElement->populateRecord(CJoinQuery, array("1", "0", "", "2011-02-28 13:11:41", ...))
#2  
+  /home/william/scm/bmbraga/clickpoll/yii/framework/db/ar/CActiveFinder.php(395): CJoinElement->runQuery(CJoinQuery)
#3  
+  /home/william/scm/bmbraga/clickpoll/yii/framework/db/ar/CActiveFinder.php(72): CJoinElement->find(CDbCriteria)
#4  
+  /home/william/scm/bmbraga/clickpoll/yii/framework/db/ar/CActiveRecord.php(1242): CActiveFinder->query(CDbCriteria, true)
#5  
+  /home/william/scm/bmbraga/clickpoll/yii/framework/db/ar/CActiveRecord.php(1323): CActiveRecord->query(CDbCriteria, true)
#6  
+  /home/william/scm/bmbraga/clickpoll/poll/protected/controllers/PollController.php(156): CActiveRecord->findAll()

有人知道我做错了什么吗？我对Yii很陌生

---

谢谢

好的，我发现问题了

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投票表需要一个主键。

好的，但是还有其他方法处理这个问题吗？谢谢你的提示。只需在模型中定义一个虚拟PrimaryKey:public function PrimaryKey（）{return'id'；}或一个组合的PrimaryKey:public function PrimaryKey（）{return array（'id1'，id2'）；}