Javascript 在tRPC 10中实现服务器端缓存中间件

发布于11月20日

我正在开发一个Next.js项目，希望实现tRPC结果的内存缓存，每个tRPC过程都能够 Select 加入一个定制的TTL.我认为tRPC的中间件将适合于此目的.不幸的是，current tRPC middleware documentation似乎不包括这一特定场景.

如何在tRPC 10中实现服务器端缓存中间件？

推荐答案

对于允许轻松实现这一点的功能请求，在Github issue上有一个相关的讨论.同时，仍然可以通过实现定制逻辑来实现这一点.

下面的示例使用node-cache作为内存缓存方法.它已经在tRPC 10.43.3上进行了测试.cachedProcedures中列出的过程被配置为 Select 进入高速缓存.

// src/app/api/middleware/cache.ts

import { initTRPC } from "@trpc/server";
import NodeCache from "node-cache";

const cacheSingleton = new NodeCache();

// A map of cached procedure names to a callable that gives a TTL in seconds
const cachedProcedures: Map<string, (() => number) | undefined> = new Map();
cachedProcedures.set("router0.procedure0", () => 2 * 3600); // 2 hours
cachedProcedures.set("router0.procedure1", () => 1800); // 30 minutes
cachedProcedures.set("router1.procedure0", secondsUntilMidnight); // dynamic TTL
cachedProcedures.set("router1.procedure1", () => undefined); // never expires

const t = initTRPC.create();
const middlewareMarker = "middlewareMarker" as "middlewareMarker" & {
  __brand: "middlewareMarker";
};


const cacheMiddleware = t.middleware(
  async ({ ctx, next, path, type, rawInput }) => {
    if (type !== "query" || !cachedProcedures.has(path)) {
      return next();
    }
    let key = path;
    if (rawInput) {
      key += JSON.stringify(rawInput).replace(/\"/g, "'");
    }
    const cachedData = cacheSingleton.get(key);
    if (cachedData) {
      return {
        ok: true,
        data: cachedData,
        ctx,
        marker: middlewareMarker,
      };
    }
    const result = await next();

    //@ts-ignore
    // data is not defined in the type MiddlewareResult
    const dataCopy = structuredClone(result.data);

    const ttlSecondsCallable = cachedProcedures.get(path);
    if (ttlSecondsCallable) {
      cacheSingleton.set(key, dataCopy, ttlSecondsCallable());
    } else {
      cacheSingleton.set(key, dataCopy);
    }
    return result;
  }
);
export default cacheMiddleware;

// src/server/api, or wherever you define tRPC procedures

import cacheMiddleware from "@/app/api/middleware/cache";
...
export const publicProcedure = t.procedure.use(cacheMiddleware);

以下是几点意见: