mb_strlen() expects parameter 1 to be string, array given

Hi all,


Can anybody take a look at my code and tell me as to why i'm getting an error?

The following is my code

public function actionCreate()
	{
		$connection=Yii::app()->db;
		$model=new BusType;
         $model2=new BusProducts;
		// Uncomment the following line if AJAX validation is needed
 $this->performAjaxValidation($model);


//Get the number of models you will be working with 
 $maxRows =count($_POST['quantity']);



		if(isset($_POST['BusType']))
		{
			$model->attributes=$_POST['BusType'];
				$model2->attributes=$_POST['BusProducts'];
			
			if($model->save())
				{
					$bus_type_id=$model->bus_type_id;
				
					 for ($i = 0; $i < $maxRows ; $i++) 
            {
			$quantity = $_POST['quantity'][$i];
			 $product_id = $_POST['product_id'][$i];
			  $cat_id = $_POST['cat_id'][$i];
			   $subcat_id = $_POST['subcat_id'][$i]; 
			$sql = "insert into bus_products (bus_type_id,quantity,product_id,cat_id,subcat_id) values (:bus_type_id,:quantity,:product_id,:cat_id,:subcat_id)"; 
 
					  
			
$command=$connection->createCommand($sql);
$command->bindParam(":bus_type_id",$bus_type_id,PDO::PARAM_INT);
$command->bindParam(":quantity",$quantity,PDO::PARAM_INT);
$command->bindParam(":product_id",$product_id,PDO::PARAM_INT);
$command->bindParam(":cat_id",$cat_id,PDO::PARAM_INT);
$command->bindParam(":subcat_id",$subcat_id,PDO::PARAM_INT);

$command->execute();
		
							}
				$this->redirect(array('view','id'=>$model->bus_type_id));
		}
		}

		$this->render('create',array(
			'model'=>$model,
			'model2'=>$model2,
		));
	}

The error which i am getting is: mb_strlen() expects parameter 1 to be string, array given .