Update Subscription quantity at the end of the cycle

[ignaciocunado]

Description

This PR adds functionality to update the subscription count at the end of the cycle. This is needed because if a user wants to decrease their subscription count, there is currently no way to make the billing and downgrading of the count to happen at the end of the cycle.

• Related Issue: Fixes Changing subscription count at the end of cycle #228

Additional Information

I believe this PR would not break any existing functionality, but is probably considered a major release as a new column needs to be added to the database.

---

Thank you for reviewing my PR!

[Naoray]

Hi @ignaciocunado,

thank you for your contribution!

I don't think another property next_quantity is needed to be able to achieve what you want!

If I am not mistaken - @sandervanhooft, please correct me if I am wrong - you could create an OrderItemObserver that reacts to an OrderItem who is being created.

<?php

namespace App\Observers;

use Laravel\Cashier\Order\OrderItem;
use Laravel\Cashier\Subscription;

class OrderItemObserver
{
    public function creating(OrderItem $orderItem): void
    {
        $orderItem->quantity -= 1;

        if (!$orderItem->orderableIsSet()) {
            return;
        }

        // we only want to decrement the quantity of subscriptions
        // that are set to process in the future
        if ($orderItem->process_at->lessThanOrEqualTo(now())) {
            return;
        }

        /** @var Subscription $subscription */
        $subscription = $orderItem->orderable;

        if ($subscription->quantity === 1) {
            // quantity would be 0 now
            // you can cancel the subscription or do something else
            return;
        }

        $subscription->decrement('quantity');   
    }
}

// in AppServiceProvider
use App\Observers\OrderItemObserver;
use Laravel\Cashier\Order\OrderItem;

// ...

public function boot(): void
{
        OrderItem::observe(OrderItemObserver::class);
}

You could also scope this functionality to a specific plan, by checking the $subscription->plan before decrementing.

---

I am aware that this is just a workaround and is far from ideal. The solution you proposed seems to be okaish, but I am not convinced this is the best path forward. I believe in future versions of this library we are able to expose more events before and after processing order items which may result in an easier implementation for this scenario!

If you have any further questions, please feel free to submit an Issue!

[ignaciocunado]

Thank you for your response and suggestion @Naoray.

However, I do not understand how this would allow a user to choose if they want to change (usually downgrade) their subscription count at the end of the cycle. Wouldn't this decrease the quantity for all subscriptions when a new order item is created?

[sandervanhooft]

Thanks @ignaciocunado !

@Naoray 's suggestion is valid in the sense that it takes care of the swapping and billing. However, the subscription quantity will be out of sync for the remainder of the cycle.

I have to agree with @ignaciocunado that adding columns similar to swap-next-cycle is desirable here.

I consider it to breaking, so best to consider this PR for next major release.

[ignaciocunado]

Hi @sandervanhooft!

Do we have an ETA for the next major release?

Thanks

[sandervanhooft]

Not as of yet

[sandervanhooft]

Switched to target v3_develop branch

[sandervanhooft]

We'll also need to make sure the subscription doesn't get restarted if it has ended.