Sace Upload File cakephp 3

gistfile1.txt

<?php

if($this->request->is('post')){
			$user_id = $this->Auth->user('id');
			$data = $this->request->getData();
			$location = WWW_ROOT."prescription/";
			$allowed_ext =  ['png' ,'jpg', 'jpeg'];
			$filename = $data['image_file']['name'];
			$temp = $data['image_file']['tmp_name'];
			$size = $data['file']['size'];

			$ext = strtolower(pathinfo($filename, PATHINFO_EXTENSION));

			if(!in_array($ext, $allowed_ext) ) {
                $msg = ["status" => 0, "msg" => "Select valid file to upload"];
			}elseif($size > 5000000) {
				$msg = ["status" => 0, "msg" => "File Size Exceeds 5MB limit"];
			}else{
				$newFileName = $user_id.date("dmyms")."-prec".$ext;
				$uploadImage = move_uploaded_file($temp, $location.$newFileName);
			}
  }