Upload to S3 using multer without a middleware function

Question

5

2

I am using multer to upload media to my s3 bucket. I am using multer-s3 as a middleware to upload media like:

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

and calling it in route as:

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

This works great. But a scenario that is not working for me is: Let say i upload one image and i want to store multiple version of it by resizing it before uploading. I am not able to call the upload function like a normal one. I want to do something like:

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

Answer 1

Use multer-s3-transform middleware to handle S3 upload with file transformation 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'))