add event handler class

[xavdid-stripe]

Why?

We've been designing a streamlined approach to handling incoming events that is easy to get right and hard to get wrong. This PR has the initial implementation of this new system.

NOTE: final names for classes / methods are still being gaveled, so don't worry about those for now. Weigh in on this doc if you have strong feelings there!

The only other pending item is to add a method to allow handling a webhook without verifying the signature. This is good for testing and for Event Bridge, which doesn't use the signature-based verification. Otherwise, this is ready for review.

What?

• add EventHandler class
• add event handler constructor on StripeClient
• add tests

Example usage

client = StripeClient(api_key)
handler = client.router(
    webhook_secret, lambda e, cli, details: print("ignoring unhandled")
)


@handler.on_V1BillingMeterNoMeterFoundEventNotification
def handle_missing_meter(
    notif: V1BillingMeterNoMeterFoundEventNotification, client: StripeClient
):
    event = notif.fetch_event()
    print(f"Err! No meter found: {event.data.developer_message_summary}")


@app.route("/webhook", methods=["POST"])
def webhook():
    webhook_body = request.data
    sig_header = request.headers.get("Stripe-Signature")

    try:
        handler.handle(webhook_body, sig_header)
        return jsonify(success=True), 200
    except Exception as e:
        return jsonify(error=str(e)), 500

See Also

• DEVSDK-2822
• ⚠️ Add strongly typed EventNotifications #1538

[jar-stripe]

we need to address concurrency here; the GIL may not save us because it releases on IO operations.

[jar-stripe]

other than the concurrency issue around setting stripe context, this looks good!