View file

$form=$this->beginWidget('CActiveForm', array(

'id'=>'registration-form',
'enableAjaxValidation'=>true,
'htmlOptions' => array('enctype' => 'multipart/form-data'),

));

<?php echo $form->labelEx($model,'csv_file'); ?> <?php echo $form->fileField($model,'csv_file'); ?> <?php echo $form->error($model, 'csv_file'); ?> <?php echo CHtml::submitButton('Upload CSV',array("class"=>"")); ?> <?php echo $form->errorSummary($model); ?>

$this->endWidget();

Model file

public function rules()

{
            array('csv_file',
	      'file', 'types' => 'csv',
	      'maxSize'=>5242880,
	      'allowEmpty' => true,
	      'wrongType'=>'Only csv allowed.',
	      'tooLarge'=>'File too large! 5MB is the limit'),
   }

public function attributeLabels()

{
           'csv_file'=>'Upload CSV File',
    }

Controller file

public function actionImport() {

	$model = new Registration;
	//$file = CUploadedFile::getInstance($model,'csv_file');
	if(isset($_POST['Registration']))
	{
		$model->attributes=$_POST['Registration'];
		if(!empty($_FILES['Registration']['tmp_name']['csv_file']))
		{
			$file = CUploadedFile::getInstance($model,'csv_file');
			

			$fp = fopen($file->tempName, 'r');
			if($fp)
			{
				//	$line = fgetcsv($fp, 1000, ",");
				//	print_r($line); exit;
				$first_time = true;
			 do {
			 	if ($first_time == true) {
			 		$first_time = false;
			 		continue;
			 	}
					$model = new Registration;
					$model->firstname = $line[0];
					$model->lastname  = $line[1];

					$model->save();

				}while( ($line = fgetcsv($fp, 1000, ";")) != FALSE);
				$this->redirect('././index');

			}
			//    echo	 $content = fread($fp, filesize($file->tempName));
				
		}

	}

	$this->render('import', array('model' => $model) );

}