使用没有中间件功能的multer上传到S3

Question

我正在使用 multer 将媒体上传到我的 s3 存储桶。我正在使用 multer-s3 作为中间件来上传媒体，例如：

const upload = multer({
  storage: multerS3({
    s3: s3,
    bucket: myBucket,
    key: function (req, file, cb) {
      cb(null, new Date().getTime() + '_' + file.originalname)
    }
  })
});

并在路由中调用它：

router.post("/media",upload.single("media"))

效果很好。但是一个不适合我的场景是：假设我上传了一张图片，我想通过在上传之前调整它的大小来存储它的多个版本。我无法像正常那样调用上传功能。我想做类似的事情：

let thumbnail = myFunctionToReturnImageFile(req.file);
upload(thumbnail);

我知道我需要发送一些 multi-part/form-part 但我找不到解决方案。如果你给我推荐一些东西会很棒。

Answer 1

您可以尝试使用 Node.js 图片处理，例如 sharp 调整大小，然后上传到 S3。

sharp(req.file)
  .resize(320, 240)
  .toBuffer()
  .then(thumbnail => { upload(thumbnail) })
  .catch( err => { ... });

Answer 2

Multer 是一个 busboy 包装器。您可以使用 busboy 而不是 multer 来处理请求并进行所需的所有操作。

const Busboy = require('busboy');

router.post('/media', function(req, res) {

    var busboy = new Busboy({ headers: req.headers });

    busboy.on('file', function(fieldname, file, filename, encoding, mimetype) {

      console.log('File ' + filename + ' upload incoming');

      
      file.on('end', function() {
         console.log('File ' + filename + ' upload finished');

         // make all you want, eg:
         let thumbnail = myFunctionToReturnImageFile(file);
         upload(thumbnail);

         res.send('file uploaded');
      });
    });
});

Answer 3

选项 1 - 使用 multer-s3-transform middleware to handle S3 upload with file transformations, like image resizing using sharp.

const multer = require('multer')
const multerS3 = require('multer-s3-transform')
const sharp = require('sharp')
const AWS = require('aws-sdk')
const S3 = new AWS.S3({
    accessKeyId: ...,
    secretAccessKey: ...
})

const upload = multer({
  storage: multerS3({
    s3: S3,
    bucket: ...,
    shouldTransform: true,
    transforms: [
      {
        id: 'original',
        key: (req, file, cb) => cb(null, new Date().getTime() + '_' + req.file.originalname),
        transform: (req, file, cb) => cb(null, sharp().jpg())
      },
      {
        id: 'large',
        key: (req, file, cb) => cb(null, new Date().getTime() + '_large_' + req.file.originalname),
        transform: (req, file, cb) => cb(null, sharp().resize(1200, 900).jpg())
      },
      {
        id: 'small',
        key: (req, file, cb) => cb(null, new Date().getTime() + '_small_' + req.file.originalname),
        transform: (req, file, cb) => cb(null, sharp().resize(400, 300).jpg())
      }
    ]
  })
})

router.post('/media', upload.single('media'))

选项 2 - 如果您坚持手动操作，您可以使用普通 multer 来处理传入文件，使用 sharp 调整大小并使用 AWS-SDK.

将每个调整大小的文件上传到 S3

const multer = require('multer')
const sharp = require('sharp')
const AWS = require('aws-sdk')
const S3 = new AWS.S3({
    accessKeyId: ...,
    secretAccessKey: ...
})

router.post('/media', multer().single('media'), (req, res) => {
  // req.file represents the uploaded file
  let time = new Date().getTime()
  
  Promise.all([
    // original file
    S3.upload({
      Bucket: ...,
      Key: time + '_' + req.file.originalname,
      Body: req.file.buffer
    }),
    
    // large preview
    sharp(req.file)
      .resize(1200, 900)
      .toBuffer()
      .then(resized => S3.upload({
        Bucket: ...,
        Key: time + '_large_' + req.file.originalname,
        Body: resized
      }).promise()),
    
    // small thumbnail
    sharp(req.file)
      .resize(400, 300)
      .toBuffer()
      .then(resized => S3.upload({
        Bucket: ...,
        Key: time + '_small_' + req.file.originalname,
        Body: resized
      }).promise()),
  ])
  .then(() => res.send("Images uploaded"))
  .catch(e => {
    console.warn(e) // debug this error
    res.status(500).send("Unable to upload images")
  })
})

使用没有中间件功能的multer上传到S3

Upload to S3 using multer without a middleware function

node.js

express

amazon-s3

multer

multer-s3