public function actionBidit(){
if(!Yii::$app->user->isGuest)
{
$inv = new FillInvestForm();
if($inv->load(Yii::$app->request->post())) {
Yii::info("xxxxxxxx".VarDumper::dumpAsString($inv->attributes));
if($inv->makeInvest()){
.......
}
}
$loan= Loan::findOne($_GET['loanid']);
$inv->bidder="aaaaaa";
return $this->render('a',['model' => $inv]);
}else{
return $this->redirect("/index.php?r=site/login");
}
}

<?php $form = ActiveForm::begin(['id' => 'form-loan',
'fieldConfig' => [ 'template'=>"{input}n{error}", ],
]);
?>
<?= $form->field($model,'bidder')->hiddenInput(['style'=>'width:240px']);?>
<?php ActiveForm::end(); ?>

class FillInvestForm extends Model
{
public $amount;
public $phone;
public $loan_rate;
//public $invest_fee;
public $wmstat;

public $loanid;
public $bidder;
/**
 * @inheritdoc
 */
public function rules()
{
    return [
['loanid',
'bidder',
'amount',
'phone',
'loan_rate',
'wmstat'],'required'  ];
}

public function attributeLabels()
{
    return [
'loanid'=>'',
'bidder'=>'',
'amount'=>'',
'phone'=>'',
'loan_rate'=>'',
'wmstat'=>''];
}

public function makeInvest()
{
    Yii::info("####".VarDumper::dumpAsString($this->attributes));
    if ($this->validate()) {
        return Invest::create($this->attributes);
    }

    return -1;
}
}

2015-04-01 18:14:31 [61.135.152.208][5][326330r588imhfs6853n90suv4][error][yiibaseErrorException:256] exception 'yiibaseErrorException' with message 'Exception 'ReflectionException' with message 'Class bidder does not exist' in /home/www/womitest/vendor/yiisoft/yii2/di/Container.php:408

Stack trace:
#0 /home/www/womitest/vendor/yiisoft/yii2/di/Container.php(408): ReflectionClass->__construct('bidder')
#1 /home/www/womitest/vendor/yiisoft/yii2/di/Container.php(354): yiidiContainer->getDependencies('bidder')
#2 /home/www/womitest/vendor/yiisoft/yii2/di/Container.php(147): yiidiContainer->build('bidder', Array, Array)
#3 /home/www/womitest/vendor/yiisoft/yii2/BaseYii.php(344): yiidiContainer->get('bidder', Array, Array)
#4 /home/www/womitest/vendor/yiisoft/yii2/validators/Validator.php(204): yiiBaseYii::createObject(Array)
#5 /home/www/womitest/vendor/yiisoft/yii2/base/Model.php(422): yiivalidatorsValidator::createValidator('bidder', Object(frontendmodelsFillInvestForm), Array, Array)
#6 /home/www/womitest/vendor/yiisoft/yii2/base/Model.php(386): yiibaseModel->createValidators()
#7 /home/www/womitest/vendor/yiisoft/yii2/base/Model.php(184): yiibaseModel->getValidators()
#8 /home/www/womitest/vendor/yiisoft/yii2/base/Model.php(715): yiibaseModel->scenarios()
#9 /home/www/womitest/vendor/yiisoft/yii2/widgets/ActiveField.php(699): yiibaseModel->activeAttributes()
#10 /home/www/womitest/vendor/yiisoft/yii2/widgets/ActiveField.php(202): yiiwidgetsActiveField->getClientOptions()
#11 /home/www/womitest/vendor/yiisoft/yii2/widgets/ActiveField.php(193): yiiwidgetsActiveField->begin()
#12 /home/www/womitest/vendor/yiisoft/yii2-bootstrap/ActiveField.php(188): yiiwidgetsActiveField->render(NULL)
#13 /home/www/womitest/vendor/yiisoft/yii2/widgets/ActiveField.php(149): yiibootstrapActiveField->render()
#14 /home/www/womitest/frontend/themes/default/invest/a.php(21): yiiwidgetsActiveField->__toString()
#15 /home/www/womitest/vendor/yiisoft/yii2/base/View.php(325): require('/home/www/womit...')
#16 /home/www/womitest/vendor/yiisoft/yii2/base/View.php(247): yiibaseView->renderPhpFile('/home/www/womit...', Array)
#17 /home/www/womitest/vendor/yiisoft/yii2/base/View.php(149): yiibaseView->renderFile('/home/www/womit...', Array, Object(frontendcontrollersInvestController))
#18 /home/www/womitest/vendor/yiisoft/yii2/base/Controller.php(367): yiibaseView->render('a', Array, Object(frontendcontrollersInvestController))
#19 /home/www/womitest/frontend/controllers/InvestController.php(50): yiibaseController->render('a', Array)