443 Pattern Idempotency 4745dd71

Use Workflow IDs for Idempotency

Assign a workflow ID to ensure a workflow executes only once, even if called multiple times. This prevents duplicate side effects like double payments.

Incorrect (no idempotency):

async function processPaymentFn(orderId: string, amount: number) {
  await DBOS.runStep(() => chargeCard(amount), { name: "chargeCard" });
  await DBOS.runStep(() => updateOrder(orderId), { name: "updateOrder" });
}
const processPayment = DBOS.registerWorkflow(processPaymentFn);

// Multiple calls could charge the card multiple times!
await processPayment("order-123", 50);
await processPayment("order-123", 50); // Double charge!

Correct (with workflow ID):

async function processPaymentFn(orderId: string, amount: number) {
  await DBOS.runStep(() => chargeCard(amount), { name: "chargeCard" });
  await DBOS.runStep(() => updateOrder(orderId), { name: "updateOrder" });
}
const processPayment = DBOS.registerWorkflow(processPaymentFn);

// Same workflow ID = only one execution
const workflowID = `payment-${orderId}`;
await DBOS.startWorkflow(processPayment, { workflowID })("order-123", 50);
await DBOS.startWorkflow(processPayment, { workflowID })("order-123", 50);
// Second call returns the result of the first execution

Access the current workflow ID inside a workflow:

async function myWorkflowFn() {
  const currentID = DBOS.workflowID;
  console.log(`Running workflow: ${currentID}`);
}

Workflow IDs must be globally unique for your application. If not set, a random UUID is generated.

Reference: Workflow IDs and Idempotency