Yii2 behavior to link a filesystem resource to an ActiveRecord instance

FileSystemResource.php

<?php

namespace common\models;
use yii\base\Behavior;
use yii\db\ActiveRecord;
use yii\web\UploadedFile;

/**
 * @author: Arleigh Dickerson
 */
class FileSystemResource extends Behavior {
	public $path;
	public $attributeName;
	private $file;

	public function init() {
		parent::init();
		assert($this -> path != null);
		assert($this -> attributeName != null);
	}

	public function events() {
		return [
		ActiveRecord::EVENT_AFTER_INSERT => 'afterSave',
		ActiveRecord::EVENT_AFTER_UPDATE => 'afterSave',
		ActiveRecord::EVENT_AFTER_DELETE => 'afterDelete', ];
	}

	public function afterSave($event) {
		$this -> file = UploadedFile::getInstance($this -> owner, $this->attributeName);
		if ($this -> file != null) {
			$this->deleteFile();
			$filename = $this -> path . $this -> owner -> id . '.' . $this -> file -> extension;
			$this -> file -> saveAs($filename);
		}
	}

	public function afterDelete($event) {
		$this->deleteFile();
	}

	private function findFile() {
		$files = glob($this -> path . $this -> owner -> id . '.*');
		foreach ($files as $file) {
			return $file;
		}
		return null;
	}
	
	private function deleteFile(){
		$file = $this -> findFile();
		if ($file != null) {
			unlink($this -> file);
		}
	}

	public function canGetProperty($name, $checkVars = true) {
		return $name == $this -> attributeName || parent::canGetProperty($name, $checkVars);
	}
        public function canSetProperty($name, $checkVars = true){
		return $name == $this -> attributeName || parent::canSetProperty($name, $checkVars);
	}

	public function __get($name) {
		return $name == $this -> attributeName ? $this -> findFile() : parent::__get($name);
	}

	public function __set($name, $value) {
		if ($name == $this -> attributeName) {
			$this -> file = $value;
		} else {
			parent::__set($name, $value);
		}
	}
}

I wrote this because I didn't want to deal with avatars as BLOBs in the database. Usage :
In ActiveRecord subclass:
class MyActiveRecordSubclass extends ActiveRecord {
//...//
public function behaviors() {
return [[
'class' => FileSystemResource::className(),
'path' => '/path/to/storage/dir/',
'attributeName' => 'whatevs']];
}
//...//
}
$model = new MyActiveRecordSubclass;
//....
$model->whatevs; //return the file or null if no file found