Naveed | Web3Auth

[heavy token]

Hi there, yes you can attach an existing payment method to a paymentIntent.

Or I'd just set the payment method as the default_payment_method when creating the subsription.

[random glade]

Hmm so basically I use PaymentElement on the frontend for a customer to subscribe to a monthly recurring plan.

I'm assuming that I can first fetch customer's default credit card to see if they have one on file, and if so instead of showing them the UI to add the credit card I can show them some basic card details e.g. use existing card,

I assume also my create subscription intent endpoint can handle the scenario where they have a card vs without one

subscriptionParams := &stripe.SubscriptionParams{
        Customer:        stripe.String(customerID),
        Items:           priceItems,
        PaymentBehavior: stripe.String("default_incomplete"),
        PaymentSettings: &stripe.SubscriptionPaymentSettingsParams{
            SaveDefaultPaymentMethod: stripe.String(string(stripe.SubscriptionPaymentSettingsSaveDefaultPaymentMethodOnSubscription)),
        },
        CollectionMethod:   stripe.String(string(stripe.SubscriptionCollectionMethodChargeAutomatically)),
        BillingCycleAnchor: stripe.Int64(currentMonthEnd.Unix()),
    }
    subscriptionParams.AddExpand("latest_invoice.payment_intent")
    subscription, err := sub.New(subscriptionParams)
    if err != nil {
        log.WithField("customer_id", customerID).WithField("error", err).Error("Failed to create stripe subscription")
        return nil, utils.NewUnexpectedError("Failed to create subscription intent", nil)
    }

this is how im setting up subscriptionParams

its doing save default payment

[fallow patio]

Hey! Taking over for my colleague. Let me catch up.

[fallow patio]

Yes that's a good option

Are you facing any particular issue with this integration so ?

[random glade]

im going to try it out, but im just wondering whats the behaviour of payment element on the frontend if i were to feed it the payment intent with default payment method attached

and btw im kind of confused about which card gets used if there are a bunch of non-default cards set up on customer account

in the above example where customer inputs their card details it will save it to their account

but i think it wont set it also as their default account

previously in our app we had customers simply set up their card (using setup intents api)

after setting up, i would set up the card to be default

with another api call

[fallow patio]

You simply don't need to show the PaymentElement as you have the PaymentMethod already

[fallow patio]

That's up to you/your customer to choose

[random glade]

right what i was assuming though that maybe itd prefill card details

[fallow patio]

Why you want to prefill card details ? if the customer has already PaymentMethod registered you can simply reuse it, without asking the merchant to reauthenticate their card agains

But in all cases, the card prefill can be managed by the customer browser and not Stripe Elements

[random glade]

oh right...

ok and basically after that ill need to also be able to handle changing of subscriptions

e.g. changing from basic -> growth -> scale etc. etc.

I guess i can simply modify subscription items in the backend

update might require payment method though

if its prorated

how does it look from customer perspective if theyve paid for growth

then want to change to scale?

at this point card has been added

im not sure if i should use create subscription intent endpoint again since itd create a new subscription

[fallow patio]

yes just do an api call udpate

[fallow patio]

the default payment method in the subscription will be used
https://stripe.com/docs/api/subscriptions/object#subscription_object-default_payment_method
No need for another Payment Method unless there is problem with the previous Payment Method

[fallow patio]

They can update, for the next billing cycle they will observe an increase in the invoice amount.

[random glade]

hmm ok a simple api endpoint to update sub items

[fallow patio]

yes, try using Stripe test clock and do some simulation :
https://stripe.com/docs/billing/testing/test-clocks

[random glade]

oh thatll help a lot

One more thing though, are subscriptions by default configured to charge default credit card

e.g. as id mentioned before i had a setup intent flow where users would set up their credit card

but not sure whatever subscriptions i create would make use of that credit card or not

e.g. if i created sub like this

// create subscription on Stripe
    subscriptionParams := &stripe.SubscriptionParams{
        Customer: stripe.String(cus.StripeID),
        Items: []*stripe.SubscriptionItemsParams{
            {
                Price: stripe.String(priceID),
            },
        },
        BillingCycleAnchor: stripe.Int64(nextMonthStart.Unix()),
        CollectionMethod:   stripe.String(string(stripe.SubscriptionCollectionMethodChargeAutomatically)),
        ProrationBehavior:  stripe.String(string(stripe.SubscriptionProrationBehaviorNone)),
    }

[fallow patio]

Add the default_payment_method too when creating the subscription:
https://stripe.com/docs/api/subscriptions/create#create_subscription-default_payment_method