Examples
Payment Retries
This example demonstrates a payment retry process using Upstash Workflow. The following example handles retrying a payment, sending emails, and suspending accounts.
Use Case
Our workflow will:
- Attempt to process a payment
- Retry the payment if it fails with a 24-hour delay
- If the payment succeeds:
- Unsuspend the user's account if it was suspended
- Send an invoice email
- If the payment fails after 3 retries:
- Suspend the user's account
Code Example
api/workflow/route.ts
import { serve } from "@upstash/workflow/nextjs";type ChargeUserPayload = { email: string;};export const { POST } = serve<ChargeUserPayload>(async (context) => { const { email } = context.requestPayload; for (let i = 0; i < 3; i++) { // attempt to charge the user const result = await context.run("charge customer", async () => { try { return await chargeCustomer(i + 1), } catch (e) { console.error(e); return } }); if (!result) { // Wait for a day await context.sleep("wait for retry", 24 * 60 * 60); } else { // Unsuspend User const isSuspended = await context.run("check suspension", async () => { return await checkSuspension(email); }); if (isSuspended) { await context.run("unsuspend user", async () => { await unsuspendUser(email); }); } // send invoice email await context.run("send invoice email", async () => { await sendEmail( email, `Payment successful. Invoice: ${result.invoiceId}, Total cost: $${result.totalCost}` ); }); // by returning, we end the workflow run return; } } // suspend user if the user isn't suspended const isSuspended = await context.run("check suspension", async () => { return await checkSuspension(email); }); if (!isSuspended) { await context.run("suspend user", async () => { await suspendUser(email); }); await context.run("send suspended email", async () => { await sendEmail( email, "Your account has been suspended due to payment failure. Please update your payment method." ); }); }});async function sendEmail(email: string, content: string) { // Implement the logic to send an email console.log("Sending email to", email, "with content:", content);}async function checkSuspension(email: string) { // Implement the logic to check if the user is suspended console.log("Checking suspension status for", email); return true;}async function suspendUser(email: string) { // Implement the logic to suspend the user console.log("Suspending the user", email);}async function unsuspendUser(email: string) { // Implement the logic to unsuspend the user console.log("Unsuspending the user", email);}async function chargeCustomer(attempt: number) { // Implement the logic to charge the customer console.log("Charging the customer"); if (attempt <= 2) { throw new Error("Payment failed"); } return { invoiceId: "INV123", totalCost: 100, } as const;}main.py
from fastapi import FastAPIfrom typing import TypedDict, Optionalfrom dataclasses import dataclassfrom upstash_workflow.fastapi import Servefrom upstash_workflow import AsyncWorkflowContextapp = FastAPI()serve = Serve(app)@dataclassclass ChargeResult: invoice_id: str total_cost: floatclass ChargeUserPayload(TypedDict): email: strasync def send_email(email: str, content: str) -> None: # Implement the logic to send an email print("Sending email to", email, "with content:", content)async def check_suspension(email: str) -> bool: # Implement the logic to check if the user is suspended print("Checking suspension status for", email) return Trueasync def suspend_user(email: str) -> None: # Implement the logic to suspend the user print("Suspending the user", email)async def unsuspend_user(email: str) -> None: # Implement the logic to unsuspend the user print("Unsuspending the user", email)async def charge_customer(attempt: int) -> Optional[ChargeResult]: # Implement the logic to charge the customer print("Charging the customer") if attempt <= 2: raise Exception("Payment failed") return ChargeResult(invoice_id="INV123", total_cost=100)@serve.post("/payment-retries")async def payment_retries(context: AsyncWorkflowContext[ChargeUserPayload]) -> None: email = context.request_payload["email"] async def _check_suspension() -> bool: return await check_suspension(email) for i in range(3): # attempt to charge the user async def _charge_customer() -> Optional[ChargeResult]: try: return await charge_customer(i + 1) except Exception as e: print(f"Error: {e}") return None result = await context.run("charge customer", _charge_customer) if not result: # Wait for a day await context.sleep("wait for retry", 24 * 60 * 60) else: # Unsuspend User is_suspended = await context.run("check suspension", _check_suspension) if is_suspended: async def _unsuspend_user() -> None: await unsuspend_user(email) await context.run("unsuspend user", _unsuspend_user) # send invoice email async def _send_invoice_email() -> None: await send_email( email, f"Payment successful. Invoice: {result.invoice_id}, Total cost: ${result.total_cost}", ) await context.run("send invoice email", _send_invoice_email) # by returning, we end the workflow run return # suspend user if the user isn't suspended is_suspended = await context.run("check suspension", _check_suspension) if not is_suspended: async def _suspend_user() -> None: await suspend_user(email) await context.run("suspend user", _suspend_user) async def _send_suspended_email() -> None: await send_email( email, "Your account has been suspended due to payment failure. Please update your payment method.", ) await context.run("send suspended email", _send_suspended_email)Code Breakdown
1. Charge Customer
We attempt to charge the customer:
TypeScript
const result = await context.run("charge customer", async () => { try { return await chargeCustomer(i + 1), } catch (e) { console.error(e); return }});Python
async def _charge_customer() -> Optional[ChargeResult]: try: return await charge_customer(i + 1) except Exception as e: print(f"Error: {e}") return Noneresult = await context.run("charge customer", _charge_customer)If we haven't put a try-catch block here, the workflow would have retried the step. However, because we want to run custom logic when the payment fails, we catch the error here.
2. Retry Payment
We try to charge the customer 3 times with a 24-hour delay between each attempt:
TypeScript
for (let i = 0; i < 3; i++) { // attempt to charge the customer if (!result) { // Wait for a day await context.sleep("wait for retry", 24 * 60 * 60); } else { // Payment succeeded // Unsuspend user, send invoice email // end the workflow: return; }}Python
for i in range(3): # attempt to charge the customer if not result: # Wait for a day await context.sleep("wait for retry", 24 * 60 * 60) else: # Payment succeeded # Unsuspend user, send invoice email # end the workflow: return3. If Payment Succeeds
3.1. Unsuspend User
We check if the user is suspended and unsuspend them if they are:
TypeScript
const isSuspended = await context.run("check suspension", async () => { return await checkSuspension(email);});if (isSuspended) { await context.run("unsuspend user", async () => { await unsuspendUser(email); });}Python
async def _check_suspension() -> bool: return await check_suspension(email)is_suspended = await context.run("check suspension", _check_suspension)if is_suspended: async def _unsuspend_user() -> None: await unsuspend_user(email) await context.run("unsuspend user", _unsuspend_user)3.2. Send Invoice Email
We send an invoice we got from the payment step to the user:
TypeScript
await context.run("send invoice email", async () => { await sendEmail( email, `Payment successful. Invoice: ${result.invoiceId}, Total cost: $${result.totalCost}` );});Python
async def _send_invoice_email() -> None: await send_email( email, f"Payment successful. Invoice: {result.invoice_id}, Total cost: ${result.total_cost}", )await context.run("send invoice email", _send_invoice_email)One of the biggest advantages of using Upstash Workflow is that you have access to the result of the previous steps. This allows you to pass data between steps without having to store it in a database.
4. If Payment Fails After 3 Retries
4.1. Suspend User
If the payment fails after 3 retries, we suspend the user and send them an email to notify them:
TypeScript
const isSuspended = await context.run("check suspension", async () => { return await checkSuspension(email);});if (!isSuspended) { await context.run("suspend user", async () => { await suspendUser(email); }); await context.run("send suspended email", async () => { await sendEmail( context.requestPayload.email, "Your account has been suspended due to payment failure. Please update your payment method." ); });}Python
async def _check_suspension() -> bool: return await check_suspension(email)is_suspended = await context.run("check suspension", _check_suspension)if not is_suspended: async def _suspend_user() -> None: await suspend_user(email) await context.run("suspend user", _suspend_user) async def _send_suspended_email() -> None: await send_email( email, "Your account has been suspended due to payment failure. Please update your payment method.", ) await context.run("send suspended email", _send_suspended_email)