multer-cloud-storage

multer-cloud-storage is a multer custom store engine for Google Cloud Storage service. It is a fork from ARozar's multer-google-storage that uses latest version of Google Cloud's API, allows additional information (like destination and contentType) to be set and reduces module footprint.

Installation

npm install multer-cloud-storage --save

or

yarn add multer-cloud-storage

Usage

ES6

import * as multer from 'multer';
import * as express from 'express';
import MulterGoogleCloudStorage from 'multer-cloud-storage';

const app = express();

const uploadHandler = multer({
  storage: new MulterGoogleCloudStorage()
});

app.post('/upload', uploadHandler.any(), (req, res) => {
    console.log(req.files);
    res.json(req.files);
});

ES5 / Common.js imports

var multer = require("multer");
var express = require("express");
var multerGoogleStorage = require("multer-cloud-storage");
var app = express();
var uploadHandler = multer({
    storage: multerGoogleStorage.storageEngine()
});
app.post('/upload', uploadHandler.any(), function (req, res) {
    console.log(req.files);
    res.json(req.files);
});

NB: This package is written to work with es5 or higher. If you have an editor or IDE that can understand d.ts (typescript) type definitions you will get additional support from your tooling though you do not need to be using typescript to use this package.

Google Cloud

Creating a storage bucket

For instructions on how to create a storage bucket see the following documentation from Google.

Obtaining credentials

For instructions on how to obtain the JSON keyfile as well a projectId (contained in the key file) please refer to the following documentation from Google.

Credentials

Default method

If using the MulterGoogleCloudStorage class without passing in any configuration options then the following environment variables will need to be set:

1. GCS_BUCKET, the name of the bucket to save to.
2. GCLOUD_PROJECT, this is your projectId. It can be found in the json credentials that you generated.
3. GCS_KEYFILE, this is the path to the json key that you generated.

Explicit method

The constructor of the MulterGoogleCloudStorage class can be passed an optional configuration object.

Parameter Name	Type	Sample Value	Default Value	Notes
acl	string	"publicRead"	"private"	Accepted values are defined in predefinedAcl options
autoRetry	boolean	true	true
bucket	string	"mybucketname"		Takes precedence over GCS_BUCKET
contentType	function	(request, file): string
contentType	string	"application/pdf"		If set, this value will be used in place of file.mimetype
destination	string	"my_folder/"	""	Despite Google Cloud Storage service stores objects in a flat name space, it is possible to list and filter them in a tree-like structure (more on How Subdirectories Work article)
email	string	"test@test.com"
filename	function	(request, file, callback): void
filename	string	"my_file.pdf"		If defined, this name will be used in place of file.originalname - use with caution, because the object can be easily overwritten (consider to configure Object Versioning and Concurrency Control)
hideFilename	boolean	true	false	If set to true, an UUID v4 will be used as object filename and Content-Type will be undefined
keyFilename	string	"./key.json"		Takes precedence over GCS_KEYFILE
maxRetries	number	5	3
projectId	string	"test-prj-1234"		Takes precedence over GCLOUD_PROJECT
uniformBucketLevelAccess	boolean	true		Signifies whether uniformBucketLevelAccess is enabled on the target bucket. When true, the predefinedAcl parameter is removed from requests as it causes 400 Bad Request responses.

Custom file naming function

If you need to customize the naming of files then you are able to provide a function that will be called before uploading the file. The third argument of the function must be a standard node callback so pass any error in the first argument (or null on sucess) and the string name of the file on success.

getFilename(req, file, cb) {
	cb(null,`${file.originalname}`);
}

Custom content-type function

If you need to customize the content-type of files then you are able to provide a function that will be called before uploading the file.

getContentType( req, file ) {
	return undefined;
}

Changes in multer API

When used with multer-cloud-storage, multer will present additional file information.

File information

Each file contains the following information:

Key	Description	Origin
fieldname	Field name specified in the form	multer
originalname	Name of the file on the user's computer	multer
encoding	Encoding type of the file	multer
mimetype	Mime type of the file	multer
bucket	Bucket name	multer-cloud-storage
destination	The pseudo-folder to which the file has been saved	multer-cloud-storage
filename	The name of the file on Google Cloud Storage	multer-cloud-storage
path	The full path to the uploaded file (basically destination+ filename)	multer-cloud-storage
contentType	Content-type defined for stored object	multer-cloud-storage
size	Size of the file in bytes	multer-cloud-storage
uri	Google Cloud Storage path	multer-cloud-storage
linkUrl	Download link for allowed users (may require authentication)	multer-cloud-storage
selfLink	The link to the stored object (used for Cloud Storage APIs requests)	multer-cloud-storage