Why am I not able to use $this is an opencart helper?

I have the following helper function in system/helper/wholesaler.php:

<?php
function is_wholesaler() {
  return $this->customer->getCustomerGroupId() != 1 ? TRUE : FALSE;
}
?>

I loaded the helper in system/startup.php

The problem is that when I try to use the function I get a fatal error "Fatal error: Using $this when not in object context". Is there a way to use $this in a helper?

One alternative option would be to send $this as an argument in is_wholesaler() or add the function in library/customer.php and call it with $this->customer->is_wholesaler() in my opencart template view files.

Answers

Try to create an object for the Customer and you can use that object as an reference for that class

$h = new Customer();
function is_wholesaler() {
    return $h->getCustomerGroupId() != 1 ? TRUE : FALSE;
}

Or you can also create reference like

return Customer::getCustomerGroupId() != 1 ? TRUE : FALSE;

$this refers to an object (class) instance, you can't use it in a individual, you can put function is_wholesaler into a class like:

class Helper{
    private $customer;

    public function __construct($customer){
        $this->customer = $customer;
    }

    function is_wholesaler() {
        return $this->customer->getCustomerGroupId() != 1 ? TRUE : FALSE;
    }
}

$customer = new Customer(); //I suppose you have a class named Customer in library/customer.php
$helper = new Helper($customer);
$is_wholesaler = $heler->is_wholesaler();

or, you just modify the function is_wholesaler it self as following:

function is_wholesaler() {
    $customer = new Customer(); //still suppose you have a class named Customer
    return $customer->getCustomerGroupId() != 1 ? TRUE : FALSE;
}

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