MrJohz Posts

MrJohz

•Created by MrJohz on 4/8/2025 in #❓-help

How can I access the session in fastify when using `useWSS: true`?

I've got a fastify/trpc application that looks something like this:

  await using app = Fastify({
    loggerInstance: logger,
    bodyLimit: 5 * 1024 * 1024,
    https: stores.config.sslOptions ?? null,
    maxParamLength: 5000,
  });

  app.register(ws);
  app.register(fastifyCookie);
  app.register(fastifySession, {
    secret: "super secret, don't look at me",
  });

  function createContext({ req }: CreateFastifyContextOptions) {
    console.log(req.session); // logs "undefined"
    return {};
  }

  app.register(fastifyTRPCPlugin, {
    prefix: "/trpc",
    useWSS: true,
    keepAlive: { enabled: true, pingMs: 50 * 1000 },
    trpcOptions: { router, onError, createContext },
  });

  await using app = Fastify({
    loggerInstance: logger,
    bodyLimit: 5 * 1024 * 1024,
    https: stores.config.sslOptions ?? null,
    maxParamLength: 5000,
  });

  app.register(ws);
  app.register(fastifyCookie);
  app.register(fastifySession, {
    secret: "super secret, don't look at me",
  });

  function createContext({ req }: CreateFastifyContextOptions) {
    console.log(req.session); // logs "undefined"
    return {};
  }

  app.register(fastifyTRPCPlugin, {
    prefix: "/trpc",
    useWSS: true,
    keepAlive: { enabled: true, pingMs: 50 * 1000 },
    trpcOptions: { router, onError, createContext },
  });

I would expect that the req in the createContext function would have access to the session (and it does if useWSS is false). However, when using TRPC with websockets, it currently consistently logs undefined. I assume this is because I'm misconfiguring something somewhere, but I'm not sure what, and I'm not sure how to solve this. Has anyone experienced this, or does anyone have any suggestions about how to resolve this? Thanks in advance!

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