Fulfill ordersBeta

Create a function on your server to fulfill successful payments. Webhooks trigger this function, and it’s called when customers are sent to your website after completing checkout. This guide refers to this function as fulfill_checkout, but you can name the function whatever you wish.

Your fulfill_checkout function must:

1. Correctly handle being called multiple times with the same Checkout Session ID.
2. Accept a Checkout Session ID as an argument.
3. Retrieve the Checkout Session from the API with the line_items property expanded.
4. Check the payment_status property to determine if it requires fulfillment.
5. Perform fulfillment of the line items.
6. Record fulfillment status for the provided Checkout Session.

Use the code below as a starting point for your fulfill_checkout function. The TODO comments indicate any functionality you must implement.

def fulfill_checkout(session_id)
  # Set your secret key. Remember to switch to your live secret key in production.
  # See your keys here: https://dashboard.stripe.com/apikeys
  Stripe.api_key = 
'sk_test_4eC39HqLyjWDarjtT1zdp7dc'

  puts "Fullfilling Checkout Session #{session_id}"

  # TODO: Make this function safe to run multiple times,
  # even concurrently, with the same session ID

  # TODO: Make sure fulfillment hasn't already been
  # peformed for this Checkout Session

  # Retrieve the Checkout Session from the API with line_items expanded
  checkout_session = Stripe::Checkout::Session.retrieve({
    id: session_id,
    expand: ['line_items'],
  })

  # Check the Checkout Session's payment_status property
  # to determine if fulfillment should be peformed
  if checkout_session.payment_status != 'unpaid'
    # TODO: Perform fulfillment of the line items

    # TODO: Record/save fulfillment status for this
    # Checkout Session
  end
end

Depending on the payment methods you accept and your business needs, you might want to have your fulfill_checkout function do the following:

• Provision access to services.
• Trigger shipment of goods.
• Save a copy of the payment details and line items in your own database.
• Send the customer a custom receipt email if you don’t have Stripe’s receipts enabled.
• Reconcile line items and quantities purchased if you allow customers to adjust quantities during checkout.
• Update inventory or stock records.

To trigger fulfillment, create a webhook event handler to listen for payment events and trigger your fulfill_checkout function.

When someone pays you, it creates a checkout.session.completed event. Set up an endpoint on your server to accept, process, and confirm receipt of these events.

Some payment methods aren’t instant, such as ACH direct debit and other bank transfers. Funds won’t be immediately available when Checkout completes. Delayed payment methods generate a checkout.session.async_payment_succeeded event when payment succeeds later.

require 'sinatra'

# Use the secret provided by Stripe CLI for local testing
# or your webhook endpoint's secret.
endpoint_secret = 'whsec_...'

post '/webhook' do
  event = nil

  # Verify webhook signature and extract the event
  # See https://stripe.com/docs/webhooks#verify-events for more information.
  begin
    sig_header = request.env['HTTP_STRIPE_SIGNATURE']
    payload = request.body.read
    event = Stripe::Webhook.construct_event(payload, sig_header, endpoint_secret)
  rescue JSON::ParserError => e
    # Invalid payload
    return status 400
  rescue Stripe::SignatureVerificationError => e
    # Invalid signature
    return status 400
  end

  if event['type'] == 'checkout.session.completed' ||
  event['type'] == 'checkout.session.async_payment_succeeded'
    fulfill_checkout(event['data']['object']['id'])
  end

  status 200
end

You might also want to listen for and handle checkout.session.async_payment_failed events. For example, you can send an email to your customer when a delayed payment fails.

The quickest way to develop and test your webhook event handler is with the Stripe CLI. If you don’t have the Stripe CLI, follow the install guide to get started.

When the Stripe CLI is installed, you can test your event handler locally. Run your server (for example, on localhost:4242), then run the stripe listen command to have the Stripe CLI forward events to your local server:

stripe listen --forward-to localhost:4242/webhook

Ready! Your webhook signing secret is 'whsec_<REDACTED>' (^C to quit)

Add the webhook secret (whsec_...) to your event handling code, then test fulfillment by going through your checkout as a customer.

When the payment completes, verify the following:

• On your command line, where stripe listen is running, it shows a checkout.session.completed event forwarded to your local server.
• Your server logs show the expected output from your fulfill_checkout function.

After testing locally, get your webhook event handler up and running on your server. Next, create a webhook endpoint to send checkout.session.completed events to your server, then test the checkout flow again.

Listening to webhooks is required to make sure you always trigger fulfillment for every payment, but webhooks can sometimes be delayed. To optimize your payment flow and guarantee immediate fulfillment when your customer is present, trigger fulfillment from your landing page as well. You can can configure the landing page by passing return_url when creating the Checkout Session, or passing returnUrl to confirm on the front end.

Use the Checkout Session ID from the URL you specified to do the following:

1. When your server receives a request for your checkout landing page, extract the Checkout Session ID from the URL.
2. Run your fulfill_checkout function with the ID provided.
3. Render the page after the fulfillment attempt is complete.

When you render your landing page you can display the following:

• Details from the fulfillment process.
• Links or information about services the customer now has access to.
• Shipping or logistical details for physical goods.