Streaming multer storage engine for Minio

multer-minio-storage.ts

/* global Express */
import { Request } from 'express'
import { Client, ClientOptions, UploadedObjectInfo } from 'minio'
import multer from 'multer'
import path from 'path'

type FilenameCallbackType = (req: Request, file: Express.Multer.File) => string
type HandleFileCallbackInfoType = Partial<Express.Multer.File> & { objectinfo?: UploadedObjectInfo }
type HandleFileCallbackType = (error?: any, info?: HandleFileCallbackInfoType) => void
const defaultFilenameCallback:FilenameCallbackType = (_req, file) => {
  const fileExt = path.extname(file.originalname)
  return `${Date.now()}${fileExt}`
}

type Options = {
  filename?: FilenameCallbackType
  bucket: string
  clientOptions: ClientOptions
}

class MulterMinioStorage implements multer.StorageEngine {
  private filename: FilenameCallbackType
  private bucket: string
  private minioClient: Client

  constructor (opts: Options) {
    this.filename = opts.filename || defaultFilenameCallback
    this.bucket = opts.bucket
    this.minioClient = new Client(opts.clientOptions)
  }

  _handleFile (
    req: Request,
    file: Express.Multer.File,
    callback: HandleFileCallbackType
  ) {
    const fileName = this.filename(req, file)
    const fileReadStream = file.stream
    this.minioClient.putObject(this.bucket, fileName, fileReadStream)
      .then(value => {
        callback(null, {
          ...file,
          filename: fileName,
          objectinfo: value
        })
      })
      .catch(err => {
        callback(err, {})
      })
  }

  _removeFile = (_req: Request, file: Express.Multer.File, callback: (error: Error | null) => void): void => {
    this.minioClient.removeObject(this.bucket, file.filename, () => callback(null))
  }
}

export default MulterMinioStorage