idempot-js

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Fastify ​

Installation ​

bash
npm install @idempot/fastify-middleware @idempot/sqlite-store

Usage ​

javascript
import Fastify from "fastify";
import { idempotency } from "@idempot/fastify-middleware";
import { SqliteIdempotencyStore } from "@idempot/sqlite-store";

const fastify = Fastify();
const store = new SqliteIdempotencyStore({ path: ":memory:" });

// Register as a plugin - applies to all routes in this scope
fastify.register(idempotency, { store });

fastify.post("/orders", async (request, reply) => {
  const orderId = crypto.randomUUID();
  return { id: orderId, ...request.body };
});

fastify.listen({ port: 3000 });

Migration from v1.x ​

javascript
// v1.x (deprecated)
fastify.addHook("preHandler", idempotency({ store }));

// v2.x
fastify.register(idempotency, { store });

API ​

idempotency(options) ​

Creates a Fastify plugin for idempotency. The plugin registers preHandler and onSend hooks internally.

Options:

  • store (required): Storage backend implementing IdempotencyStore
  • required: Whether idempotency key is required (default: true)
  • ttlMs: Time-to-live for idempotency records in milliseconds
  • excludeFields: Fields to exclude from fingerprint calculation
  • resilience: Circuit breaker and retry options

Returns: Fastify plugin with circuit property for monitoring.