L4.2 Extend/override Cashier to add Tax feature

Question

I am using Laravel 4.2 with Cashier and I need to modify its protected function buildPayload() but I don't want to do it directly in the vendor file as I could break the code when I composer Update... How should I proceed to override this function with my own Logic ?

I currently use Cashier in one of my controller by doing:

$user->subscription('testplan')
                    ->create(Input::get('stripeToken'), [
                        'email' => 'email@email.com,
                    ]);

But I want to add a withTax() parameters... Like so:

$user->subscription('testplan')
                        ->withTax(10)
                        ->create(Input::get('stripeToken'), [
                            'email' => 'email@email.com,
                        ]);

I already know how to do it directly in the StripeGateway.php file but it's bad practice...

I know that I need to add:

protected $taxPercent = 0;

    public function withTax($tax)
    {
        $this->taxPercent = $tax;

        return $this;
    }

    protected function buildPayload()
    {
        $payload = [
            'plan' => $this->plan, 'prorate' => $this->prorate,
            'quantity' => $this->quantity, 'trial_end' => $this->getTrialEndForUpdate(),
            'tax_percent' => $this->taxPercent,
        ];

        return $payload;
    }

What I don't know is how to add this code not directly in the Cashier Original file.

Answer 1

I managed to find how to do it by myself, it's first time I do this kind of thing... Please correct me if my method is wrong!

First:

I created a Folder named Lib\Cashier like so: laravel/app/Lib/Cashier

I then created 2 files: BillableTrait.php and NewStripeGateway.php

BillableTrait.php code:

<?php namespace Lib\Cashier;

use Laravel\Cashier;
use Lib\Cashier\NewStripeGateway as StripeGateway;

trait BillableTrait {
    use Cashier\BillableTrait;

    /**
     * Get a new billing gateway instance for the given plan.
     *
     * @param  \Laravel\Cashier\PlanInterface|string|null  $plan
     * @return \Laravel\Cashier\StripeGateway
     */
    public function subscription($plan = null)
    {
        if ($plan instanceof PlanInterface) $plan = $plan->getStripeId();

        return new StripeGateway($this, $plan);
    }


}

For NewStripeGateway.php:

<?php namespace Lib\Cashier;

use Laravel\Cashier\StripeGateway;

class NewStripeGateway extends StripeGateway {

    protected $taxPercent = 0;

    public function withTax($tax)
    {
        $this->taxPercent = $tax;

        return $this;
    }

    protected function buildPayload()
    {
        $payload = [
            'plan' => $this->plan, 'prorate' => $this->prorate,
            'quantity' => $this->quantity, 'trial_end' => $this->getTrialEndForUpdate(),
            'tax_percent' => $this->taxPercent,
        ];

        return $payload;
    }
}

And then I edited my Model that use Cashier like so (only changed the USE block):

use Lib\Cashier\BillableTrait;
use Laravel\Cashier\BillableInterface;

I can now do this directly to set the tax on a subscription:

$user->subscription('testplan')
                        ->withTax(10)
                        ->create(Input::get('stripeToken'), [
                            'email' => 'email@email.com',
                        ]);

It's working perfectly!! If there is anything I did wrong, please notice me of the changes, it's first time I dig in PHP classes (traits, extends, etc) by myself..

Thank you!

Raphael