Wik

[simple whale]

Hi 👋 yes, you can use the upcoming invoice API to preview the next Invoice for a Subscription, and provide adjustments in that request to simulate changes being made to the Subscription.

This document goes into a bit more detail about that and shows an example of retrieving an upcoming Invoice for a Subscription using a new Price:
https://stripe.com/docs/billing/subscriptions/prorations#preview-proration

[wraith thicket]

Yes, but this doc mentions only changing subscription, not adding to it

I tried creating an invoice item to preview how it'll change the price, but I am getting an error

Stripe::InvoiceItem.create({
customer: 'cus_NejoWOf0IUwOmM',
price: 'price_1Mqc27JA8pMPzFjlM40EXYmT',
})

Stripe::InvalidRequestError: The price specified is set to type=recurring but this field only accepts prices with type=one_time.

So I wonder - how can I preview how the price will change if I add a second product to my current subscription?

[simple whale]

To add an additional subscription item to the preview, you'll provide the details for the new item in the subscription_items hash. When doing so you'll omit the id parameter in that hash as you want to simulate a new subscription item rather than simulate changing an existing one.
https://stripe.com/docs/api/invoices/upcoming#upcoming_invoice-subscription_items

[wraith thicket]

Great, thank you! One more question

Can I use the upcoming invoice to see how much I'd have to pay if I were to change the subscription today, not at the end of the period and taking into consideration what I paid for my current subscription (subscription_proration_behavior: "create_prorations" I think, I'm not sure how to change billing date though)

oh, I see proration date!

[simple whale]

Exactly, the subscription_proration_date field allows you to simulate making the update at a specific time. I believe that field defaults to the current time if the parameter is not provided.

[wraith thicket]

I have a user on $199/month plan (subscribed today). I want to see what Stripe will return for changing them to $19/month plan + $100/month seat. They'd be charged $0 for the next few payments as that $199 would cover the next few month, but upcoming invoice has total: 43662. Why is that?

Stripe:: Invoice.upcoming({
customer: 'cus_NejoWOf0IUwOmM',
subscription: "sub_1MtQKQJA8pMPzFjlFSgOxKiI",
subscription_proration_behavior: "create_prorations",
subscription_proration_date: proration_date,
subscription_items: [
{plan: "monthly-19usd-plus-20201101"},
{price: "price_1MoiQiJA8pMPzFjla4njMBh1"}
]
})

[queen perch]

👋 stepping in

Can you share the payload that you get back from your upcoming invoice request?

[queen perch]

Can you pull out just the lines data and format it?

That is what you want to look at specifically for why the total is the amount it is

[wraith thicket]

sure

Oh, so it looks like instead of changing $199 => $19 + $100, I did ($199 + $19 + $100) + ($19 + $100)?

How can I fix the request then? When I tried removing subscription, I got an error saying that it's mandatory

[queen perch]

Ah you added an item

Instead of replacing

You need to pass the Subscription Item ID

See https://stripe.com/docs/billing/subscriptions/upgrade-downgrade

Should look like items: [{ id: subscription.items.data[0].id, price: 'price_CBb6IXqvTLXp3f', }]

[wraith thicket]

trying

hm, still seems wrong

I did

customer: 'cus_NejoWOf0IUwOmM',
subscription_proration_behavior: "create_prorations",
subscription_proration_date: proration_date,
subscription: "sub_1MtQKQJA8pMPzFjlFSgOxKiI",
subscription_items: [
id: subscription.items.data[0].id,
price: "monthly-19usd-plus-20201101",
price: "price_1MoiQiJA8pMPzFjla4njMBh1"
]
})```

hoping to see $199 => $19 + $100 change

but lines suggest it only calculated for $100 seat, ignoring the $19 bit?

I tried modelling items differently but still not luck ```items = [{
id: subscription.items.data[0].id,
price: 'monthly-19usd-plus-20201101',
},
{
id: subscription.items.data[0].id,
price: 'price_1MoiQiJA8pMPzFjla4njMBh1'
}]

Stripe::InvalidRequestError: The array you specified contains a duplicate entry: 'si_NejoWvQcxIXbxX'

any idea how to do this call to see how adding a product to an existing subscription will change it? I do not want to remove the original product though

[queen perch]

Sorry server is busy, coming back around to this

[wraith thicket]

no worries 🙌

[queen perch]

So wait you do want to add an item or you want to replace the current one?

[wraith thicket]

I'll need to jump to a call in 10 so will be inactive for 30 minutes

[queen perch]

Maybe I misunderstood

[wraith thicket]

let me rephrase 🙂

GIVEN I'm on $199 plan/month that started on 1st April
WHEN I add $100/month seat on 5th April
THEN I want to be able to preview how much I'll be charged with proration

And I am trying to figure out how to ask your API about this using the upcoming invoice mechanism

[queen perch]

Ah okay

Thanks for clarifying

Then you want ```Stripe:: Invoice.upcoming({
customer: 'cus_NejoWOf0IUwOmM',
subscription: "sub_1MtQKQJA8pMPzFjlFSgOxKiI",
subscription_proration_behavior: "create_prorations",
subscription_proration_date: proration_date,
subscription_items: [
{price: "price_1MoiQiJA8pMPzFjla4njMBh1"}
]
})

By passing plan and price you were adding two items

plan is our legacy API

price is our newer API

You will still see references to plan as we still support the legacy API

But you don't want to pass both here

[wraith thicket]

yay, it worked! just one more question, sorry 😅

[queen perch]

Glad it worked!

And no worries -- we are here to help!

[wraith thicket]

my one more question

is about coupons

I added a 10% off forever coupon

but lines show as if it was only applied to the remaining time

even though total seems correct?

customer: 'cus_NejoWOf0IUwOmM',
subscription: "sub_1MtQKQJA8pMPzFjlFSgOxKiI",
        coupon: "wik-all-forever",
subscription_items: [
{price: "price_1MoiQiJA8pMPzFjla4njMBh1", quantity: 2}
]
})```

"total": 53813,