Idempotency

curl -X POST https://api.ventry.es/v1/tickets \
  -H "Authorization: Bearer $VENTRY_KEY" \
  -H "Idempotency-Key: 7c9e6679-7425-40de-944b-e07fc1f90ae7" \
  -H "Content-Type: application/json" \
  -d '{ "ticket_type": "...", "valid_days": ["..."], "attendee": { "name": "Ada", "email": "[email protected]" } }'

await fetch("https://api.ventry.es/v1/tickets", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.VENTRY_KEY}`,
    "Idempotency-Key": "7c9e6679-7425-40de-944b-e07fc1f90ae7",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    ticket_type: "...",
    valid_days: ["..."],
    attendee: { name: "Ada", email: "[email protected]" },
  }),
});

requests.post(
    "https://api.ventry.es/v1/tickets",
    headers={
        "Authorization": f"Bearer {os.environ['VENTRY_KEY']}",
        "Idempotency-Key": "7c9e6679-7425-40de-944b-e07fc1f90ae7",
    },
    json={
        "ticket_type": "...",
        "valid_days": ["..."],
        "attendee": {"name": "Ada", "email": "[email protected]"},
    },
    timeout=30,
)

<?php
$ch = curl_init("https://api.ventry.es/v1/tickets");
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_POST => true,
    CURLOPT_HTTPHEADER => [
        "Authorization: Bearer " . getenv("VENTRY_KEY"),
        "Idempotency-Key: 7c9e6679-7425-40de-944b-e07fc1f90ae7",
        "Content-Type: application/json",
    ],
    CURLOPT_POSTFIELDS => json_encode([
        "ticket_type" => "...",
        "valid_days" => ["..."],
        "attendee" => ["name" => "Ada", "email" => "[email protected]"],
    ]),
]);

$response = json_decode(curl_exec($ch), true);
curl_close($ch);

// Good: the key is generated once and reused across retries.
const idempotencyKey = crypto.randomUUID();
await withRetries(() => createTickets(batch, idempotencyKey));

// Bad: every retry generates a new key and duplicates the batch.
await withRetries(() => createTickets(batch, crypto.randomUUID()));

import uuid

# Good: the key is generated once and reused across retries.
idempotency_key = str(uuid.uuid4())
with_retries(lambda: create_tickets(batch, idempotency_key))

# Bad: every retry generates a new key and duplicates the batch.
with_retries(lambda: create_tickets(batch, str(uuid.uuid4())))

<?php
// Good: the key is generated once and reused across retries.
$idempotencyKey = bin2hex(random_bytes(16));
withRetries(fn () => createTickets($batch, $idempotencyKey));

// Bad: every retry generates a new key and duplicates the batch.
withRetries(fn () => createTickets($batch, bin2hex(random_bytes(16))));

const idempotencyKey = `order-${order.id}-tickets`;

idempotency_key = f"order-{order.id}-tickets"

$idempotencyKey = "order-{$order->id}-tickets";

const scanId = crypto.randomUUID();  // once, when the QR is read

await checkIn(ticketCode, wristbandNfc, scanId);  // safe to retry

scan_id = str(uuid.uuid4())  # once, when the QR is read

check_in(ticket_code, wristband_nfc, scan_id)  # safe to retry

$scanId = bin2hex(random_bytes(16));  // once, when the QR is read

checkIn($ticketCode, $wristbandNfc, $scanId);  // safe to retry