Fatal Error - Call to undefined method "Customersss::throwError()" - php

Question

I created a class and try to call in a method, but however in my error log, I am getting response "Uncaught Error: Call to undefined method Customersss::throwError()", please what am I doing wrong, because I know I have created throwError(), I can't seem to be able to access the class.
Firstly the class trying to call object
$this->throwError(INVALID_DATA_TTT, "Invalid shipping fee"); //WHERE I SUSPECT ERROR IS BEING GENERATED
The full error
PHP Fatal error: Uncaught Error: Call to undefined method
Customersss::throwError() in
/home/osconliz/public_html/Osconlizapicall/customers.php:276 Stack
trace:
#0 /home/osconliz/public_html/Osconlizapicall/api.php(177): Customersss->insertNewDelivery()
#1 [internal function]: Api->create_insert_new_delivery()
#2 /home/osconliz/public_html/Osconlizapicall/rest.php(42): ReflectionMethod->invoke(Object(Api))
#3 /home/osconliz/public_html/Osconlizapicall/index.php(4): Rest->processApi()
#4 {main} thrown in /home/osconliz/public_html/Osconlizapicall/customers.php on line 276
customers.php
require_once('constants.php');
require_once('rest.php');
class Customersss {
private $id;
private $shipping_fee;
private $pickup_fee;
function setId($id){ $this->id = $id; }
function getId() { return $this->id; }
function setShipping_fee($shipping_fee){ $this->shipping_fee = $shipping_fee; }
function getShipping_fee() { return $this->shipping_fee; }
function setPickup_fee($pickup_fee){ $this->pickup_fee = $pickup_fee; }
function getPickup_fee() { return $this->pickup_fee; }
public function __construct(){
$db = new DbConnect();
$this->dbConn = $db->connect();
}
public function insertNewDelivery(){
if ($this->shipping_fee == ""){
$this->throwError(EMPTY_PARAMETER, "Empty shipping fee");
exit();
}
if ($this->shipping_fee == ""){
$this->throwError(INVALID_DATA_TTT, "Invalid shipping fee");
exit();
}
}
}
rest.php
require_once('constants.php');
class Rest {
protected $request;
protected $serviceName;
protected $param;
public function processApi(){
$api = new API;
$rMethod = new reflectionMethod('API', $this->serviceName);
if(!method_exists($api, $this->serviceName)){
$this->throwError(API_DOST_NOT_EXIST, "API does not exist");
}
$rMethod->invoke($api);
}
public function throwError($code, $message){
header("content-type: application/json");
$errorMsg = json_encode(['error' => ['status'=>$code, 'message'=>$message]]);
echo $errorMsg; exit;
}
}
constants.php
define('INVALID_DATA_TTT', 350);
define('EMPTY_PARAMETER', 404);
define('API_DOST_NOT_EXIST', 400);
define('ACCESS_TOKEN_ERRORS', 500);
api.php
require_once "customers.php";
require_once "constants.php";
class Api extends Rest {
public $dbConn;
public function __construct(){
parent::__construct();
$db = new DbConnect;
$this->dbConn = $db->connect();
}
public function create_insert_new_delivery(){
$shipping_fee= $this->validateParameter('item_category', $this->param['shipping_fee'], STRING, true);
try {
$cust = new Customersss;
} catch (Exception $e){
$this->throwError(ACCESS_TOKEN_ERRORS, $e->getMessage());
}
}

Answer 1

You are calling Rest::ThrowError() from Customersss class. It means your function is unreachable in this context.
To call this Rest method from the Customersss class, you can:
extend Rest to Customersss (see inheritance)
make ThrowError() a static method (see static)
Using inheritance:
class Customersss extends Rest { /* your properties/methods */ }
Using a static method:
class Rest {
static public function throwError($code, $message){ /* your code */ }
}
Callable with Rest::ThrowError()