如何检查重复记录DB mongodb？使用yii2

Question

我的行动

if(Yii::$app->request->post()){
            $eventName = Event::find()->select(['Event_name'])->from('Event')->where(['Calendar' => ['4']])->all();
            $model->file = $model->uploadFile($model,'file');
            $fh = fopen($_FILES['uploadfile']['tmp_name'], "r");
            while (($row = fgetcsv($fh, 0, ","))!= FALSE)
            {   
                $model = new Event();
                $model->Event_name = $row[0];
                $model->Discription =  $row[1];
                foreach ($eventName as $value){
                if($value->Event_name != $model->Event_name){
                    $model->save();
                }
            }
        }
    }
}
return $this->render('index', ['model' => $model,'value'=> $query]);

我想检查我的db（mongodb）和csv文件中的重复记录。 if condition true model将数据保存到db 否则删除旧数据并将新数据保存到db