multer-firebase-storage

Multer Storage Engine for Firebase

Installation

npm install multer-firebase-storage

Usage

Using Express:

const Express = require('express')
const Multer = require('multer')
const FirebaseStorage = require('multer-firebase-storage')
const app = new Express()

const multer = Multer({
  storage: FirebaseStorage({
    bucketName: 'your-default-bucket',
    credentials: {
      clientEmail: 'your-firebase-client-email',
      privateKey: 'your private key',
      projectId: 'your-project-id'
    }
  })
})

app.post('/file', multer.single('file'), (req, res) => {
  res.status(201).json(req.file)
})

app.listen(3000, () => {
  console.log('Example app listening on port 3000!')
})

Tweaks and options

Firebase Storage supports the following setup options:

{
    bucketName: string;
    credentials: string | { projectId: string, privateKey: string, clientEmail: string }
    directoryPath?: string
    mimeMap?: {
      [fileName: string]: string
    }
    appName?: string
    namePrefix?: string
    nameSuffix?: string
    unique?: boolean
    public?: boolean
    hooks: {
      [hookName: string]: function
    }
}

Required options

bucketName: The name of the bucket to upload to.
credentials: The credentials to use for authentication. It can be a refresh token string or the Firebase credentials object (just like the firebase admin SDK requests).
- Credentials can be provided by reading the Firebase Service Account JSON file and passing the contents as an object
- Credentials can be a set of the following properties: projectId, privateKey, clientEmail which can be obtained by the Firebase console.
- Note: The privateKey field needs to be in the same format as in the JSON file.

Optional options

directoryPath: Will be prepended to the file name to include the file in a subdirectory.
- For example: if the file name is image.jpg and the directory path is images, the resulting file name will be images/image.jpg. There's no need to add a trailing slash.
appName: Firebase allows only a single instance of its admin SDK to be executed per app. If you need more than one, specify the name of the app you want to use. Remember it needs to be unique in the application
namePrefix: The prefix to be added to the file name.
- This will append a string before the file name, but after the directory path. For example: if the file name is image.jpg and the prefix is preview_, the resulting file name will be preview_image.jpg.
nameSuffix: The suffix to be added to the file name.
- This will append a string after the file name, but before the file extension. For example: if the file name is image.jpg and the suffix is _final, the resulting file name will be image_final.jpg.
unique: If set to true, the file name will be unique by generating a time-based hash that will be appended to the end of the file name (after nameSuffix and before the file extension). If set to false, the file name will be the same as the original file name.
- For example: if the file name is image.jpg and the suffix is _final and unique is true, the resulting file name will be image_final<somehashhere>.jpg.
public: If set to true, the file will be made public and the public URL will be returned. If set to false, the file will be private.
hooks: Where you can define lifecycle hooks

Returned data

After a successful insertion, all returned data will be appended to the req.file object. Besides the original Multer properties, the following properties will be added:

fileRef: A reference to the Firebase Storage file object. You can use that to manipulate the file after the upload has been done.
- Common operations to this reference are: generating signed URLs, deleting the file, etc.
- The type of this property is the same as if you were using the Firebase Storage SDK directly with firebase.storage().bucket().file(filename)
path: The path of the file in the bucket.
bucket: The name of the bucket.
bucketRef: A reference to the Firebase Storage bucket object. You can use that to manipulate the bucket after the upload has been done.
- The type of this property is the same as if you were using the Firebase Storage SDK directly with firebase.storage().bucket(bucketname)
isPublic: If the file is public or private.
publicUrl: If the file is public, the public URL will be returned.

Using your own Firebase instance

You can pass an optional parameter to the FirebaseStorage constructor to use your own Firebase instance. In this case, the credentials and bucket options will be ignored.

const Express = require('express')
const Multer = require('multer')
const fbAdmin = require('firebase-admin')
const FirebaseStorage = require('multer-firebase-storage')
const app = new Express()

const fbInstance = fbAdmin.initializeApp({
  credential: fbAdmin.credential.cert(somecredentials),
  storageBucket: 'some bucket'
})

const multer = Multer({
  storage: FirebaseStorage({}, fbInstance)
})

app.post('/file', multer.single('file'), (req, res) => {
  res.status(201).json(req.file)
})

app.listen(3000, () => {
  console.log('Example app listening on port 3000!')
})

Lifecycle hooks

Multer-Firebase-Storage supports the following lifecycle hooks:

beforeUpload: This hook will be called before the file is uploaded to Firebase Storage.
afterUpload: This hook will be called after the file is uploaded to Firebase Storage.
beforeDelete: This hook will be called before the file is deleted from Firebase Storage.
afterDelete: This hook will be called after the file is deleted from Firebase Storage.
beforeInit: This hook will be called before the Firebase Storage instance is initialized.
afterInit: This hook will be called after the Firebase Storage instance is initialized.

Each hook has a different function signature:

beforeUpload: (req, file) => void
- req is the Express request object. file is the Multer file object.
afterUpload: (req, file, fileRef, bucketRef) => void
- req is the Express request object. file is the Multer file object. fileRef and bucketRef are the references to the Firebase Storage objects.
beforeDelete: (req, file) => void
- req is the Express request object. file is the Multer file object.
afterDelete: (req, file, fileRef, bucketRef) => void
- req is the Express request object. file is the Multer file object. fileRef and bucketRef are the references to the Firebase Storage objects.
beforeInit: (storageInstance) => void
- storageInstance is the Firebase Storage instance passed as this.
afterInit: (storageInstance, firebaseInstance) => void
- storageInstance is the Firebase Storage instance passed as this. firebaseInstance is the Firebase instance passed either as the second parameter to the FirebaseStorage constructor or the internally constructed instance.

Usage example

const Express = require('express')
const Multer = require('multer')
const FirebaseStorage = require('multer-firebase-storage')
const app = new Express()

const multer = Multer({
  storage: FirebaseStorage({
    bucketName: 'your-default-bucket',
    credentials: {
      clientEmail: 'your-firebase-client-email',
      privateKey: 'your private key',
      projectId: 'your-project-id'
    },
    hooks: {
      beforeInit (instance) {
        console.log(`before init:`, instance)
      },
      afterInit (instance, fb) {
        console.log(`after init:`, instance, fb)
      },
      beforeUpload (req, file) {
        console.log(`before upload:`, req, file)
      },
      afterUpload (req, file, fref, bref) {
        console.log(`after upload:`, req, file, fref, bref)
      },
      beforeRemove (req, file) {
        console.log(`before remove:`, req, file)
      },
      afterRemove (req, file, fref, bref) {
        console.log(`after remove:`, req, file, fref, bref)
      }
    }
  })
})

app.post('/file', multer.single('file'), (req, res) => {
  res.status(201).json(req.file)
})

app.listen(3000, () => {
  console.log('Example app listening on port 3000!')
})