在同一个类中，一个方法set（）没有获得另一个方法upload_image的值

Question

我没有获得upload_image函数的值，尽管dode似乎没问题。这是代码供参考。在下面我添加了我想在调用方法中使用vlaue的方法。

namespace  App\Product;
include_once '../../vendor/autoload.php';
use PDO;
use PDOException;
use App\Connection;

class Product extends Connection{

    private $title;

    private $category;

    private $description;

    private $image_name;

    public function set($data,$image_file){

     if(array_key_exists('image_name',$data)) {
       $this->image_name=$this->upload_image($image_file,'image_name','../..upload/');                
// this method is for uploading picture

            }
        }

        //method for upoading image to a folder
    public function upload_image($file,$image_name,$upload_dir){

        $imgFile = $file["$image_name"]["name"];

        $tmp_dir = $file["$image_name"]["tmp_name"];

        $imgSize = $file["$image_name"]["size"];

        $imgExt = strtolower(pathinfo($imgFile,PATHINFO_EXTENSION));

        //   get image extension
        $valid_extensions = array('jpeg', 'jpg', 'png', 'gif');

        // valid extensions
        $userpic = rand(1000,1000000).".".$imgExt;

        move_uploaded_file($tmp_dir,$upload_dir.$userpic);

        return $userpic;

    }


    }