如何從緩沖區返回文件流？

Question

我已經在 mysql 數據庫上存儲了我的圖像，它的大小（以字節為單位）和它的類型。

當我獲取它時，我正在取回圖像的緩沖區，現在我試圖弄清楚如何將它發送回我的客戶端以便它呈現圖像？

我的路線內的代碼：

  const img = await db.images.findByPk(parser.setValueAsBIN(p.id));

   const myReadableStreamBuffer = new streamBuffers.ReadableStreamBuffer({
    frequency: 10, // in milliseconds.
    chunkSize: img.Length, // in bytes.
  });



 myReadableStreamBuffer.put(img.dataValues.imageData);

下一步是什么？

如果我想記錄myReadableStreamBuffer

我只是得到：

Readable {   _readableState:    ReadableState {
     objectMode: false,
     highWaterMark: 16384,
     buffer: BufferList { head: null, tail: null, length: 0 },
     length: 0,
     pipes: null,
     pipesCount: 0,
     flowing: null,
     ended: false,
     endEmitted: false,
     reading: false,
     sync: true,
     needReadable: false,
     emittedReadable: false,
     readableListening: false,
     resumeScheduled: false,
     paused: true,
     emitClose: true,
     autoDestroy: false,
     destroyed: false,
     defaultEncoding: 'utf8',
     awaitDrain: 0,
     readingMore: false,
     decoder: null,
     encoding: null },   readable: true,   domain: null,   _events: [Object: null prototype] {},   _eventsCount: 0,   _maxListeners: undefined,   stopped: false,   stop: [Function],   size: [Function],   maxSize: [Function],   put: [Function],   _read: [Function] }

Answer 1

Fastify 在reply.send()方法中也支持 stream 和緩沖。

在這里如何管理它們：

const fs = require('fs')
const { Readable } = require('stream')
const fastify = require('fastify')({ logger: true })

fastify.get('/', (req, reply) => {
  const buffer = fs.readFileSync('demo.png')
  reply.type('image/png') // if you don't set the content, the image would be downloaded by browser instead of viewed
  reply.send(buffer)
})

fastify.get('/stream', (req, reply) => {
  const buffer = fs.readFileSync('demo.png') // sync just for DEMO
  const myStream = new Readable({
    read () {
      this.push(buffer)
      this.push(null)
    }
  })

  reply.type('image/png')
  reply.send(myStream)
})

fastify.listen(3000)

（我會避免stream-buffers package ，因為它似乎不再需要維護 - 問題未解決 - 並且 node.js 中的默認stream模塊已得到很大改進）