API Idempotence - sample

index.ts

const app = new Hono().post(
  "idempotence",
  validator("header", (value, ctx) => {
    const idempotencyKey = value["x-idempotency-key"];
    if (idempotencyKey == undefined || idempotencyKey === "") {
      throw new HTTPException(400, {
        message: "X-Idempotency-Key is required",
      });
    }
    return { idempotencyKey };
  }),
  async (ctx) => {
    const { idempotencyKey } = ctx.req.valid("header");
    const body = await ctx.req.json();
    if (IDEMPOTENCY_CACHE.has(idempotencyKey)) {
      return ctx.json(IDEMPOTENCY_CACHE.get(idempotencyKey));
    } else {
      const response = {
        /* ... */
      };
      IDEMPOTENCY_CACHE.set(idempotencyKey, response);
      return ctx.json(response);
    }
  },
);