Item with the same id "98" already exist

在magento项目中多次遇到这样一个错误:

Item (Bluecom_Onefieldusername_Model_Customer) with the same id "98" already exist

解决方案:

(1) 新建一个类，必须继承Varien_Object

class Mypackage_Mymodule_Model_UniqueId extends Varien_Object{

    public function getUniqueNumber(){

        list($usec, $sec) = explode(" ", microtime());
        return uniqid(mt_rand().$sec.($usec*1000000));
    }

    public function getId(){

        return $this->getUniqueNumber();
    }
}

(2)在getCollection后面使用setItemObjectClass('mymodule/uniqueId')