javascriptapifastifyprefastify-nextjs

how to access payload from fastify-http-proxy in the prehandler hook

I am developing an application where I need to hit this endpoint https://api2.transloadit.com/assemblies to upload a file of any type. I wish to add authentication params from the server before hitting the final endpoint Please Note: It is multipart/formdata that I wish to edit in the pre handler hook This is my code:

fastify.register(require("fastify-http-proxy"), {
  upstream: "https://api2.transloadit.com/assemblies",
  undici: true,
  prefix: "/api", // optional
  http2: false,
  preHandler(request, reply, next) {
    // how to access the data in request body
    console.log(request);
    next();
  },
});

But this is the output of request.body :

body: IncomingMessage {
    _readableState: ReadableState {
      objectMode: false,
      highWaterMark: 16384,
      buffer: BufferList { head: null, tail: null, length: 0 },
      length: 0,
      pipes: [],
      flowing: null,
      ended: false,
      endEmitted: false,
      reading: false,
      sync: true,
      needReadable: false,
      emittedReadable: false,
      readableListening: false,
      resumeScheduled: false,
      errorEmitted: false,
      emitClose: true,
      autoDestroy: false,
      destroyed: false,
      errored: null,
      closed: false,
      closeEmitted: false,
      defaultEncoding: 'utf8',
      awaitDrainWriters: null,
      multiAwaitDrain: false,
      readingMore: true,
      decoder: null,
      encoding: null,
      [Symbol(kPaused)]: null
    },
    _events: [Object: null prototype] { end: [Function: clearRequestTimeout] },
    _eventsCount: 1,
    _maxListeners: undefined,
    socket: Socket {
      connecting: false,
      _hadError: false,
      _parent: null,
      _host: null,
      _readableState: [ReadableState],
      _events: [Object: null prototype],
      _eventsCount: 8,
      _maxListeners: undefined,
      _writableState: [WritableState],
      allowHalfOpen: true,
      _sockname: null,
      _pendingData: null,
      _pendingEncoding: '',
      server: [Server],
      _server: [Server],
      parser: [HTTPParser],
      on: [Function: socketListenerWrap],
      addListener: [Function: socketListenerWrap],
      prependListener: [Function: socketListenerWrap],
      _paused: false,
      _httpMessage: [ServerResponse],
      [Symbol(async_id_symbol)]: 53,
      [Symbol(kHandle)]: [TCP],
      [Symbol(kSetNoDelay)]: false,
      [Symbol(lastWriteQueueSize)]: 0,
      [Symbol(timeout)]: null,
      [Symbol(kBuffer)]: null,
      [Symbol(kBufferCb)]: null,
      [Symbol(kBufferGen)]: null,
      [Symbol(kCapture)]: false,
      [Symbol(kBytesRead)]: 0,
      [Symbol(kBytesWritten)]: 0,
      [Symbol(RequestTimeout)]: undefined
    }

Solution

  • If you want to pass along auth params to the third party, you can inject them by accessing the request.raw part of the url if it's a url param based API key. In your case:

    fastify.register(require("fastify-http-proxy"), {
  upstream: "https://api2.transloadit.com/assemblies",
  undici: true,
  prefix: "/api", // optional
  http2: false,
  preHandler(request, _reply, next) {
    request.raw.url = `${request.raw.url}&apikey=${MY_API_KEY}`;
    console.log(request);
    next();
  },
});

    If the auth params are header based, you'll actually want to define the rewriteRequestHeaders function. This would look like:

    fastify.register(require("fastify-http-proxy"), {
  upstream: "https://api2.transloadit.com/assemblies",
  undici: true,
  prefix: "/api", // optional
  http2: false,
  replyOptions: {
    rewriteRequestHeaders: (_, headers) => {
        return {
          ...headers,
          'x-api-key': MY_API_KEY
        };
      }
  }
});