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express-form-post

1.4.2 • Public • Published

Express Form Post

npm version js-standard-style npm

A simple and efficient solution to handling file uploading to disk, s3, or dropbox

Note: This module works in any node.js setting. Express is not required for usage.

Why use this module?

  • Easy setup
    • abstracts set up for both dropbox and aws-s3 multipart uploads
  • Validation for the entire request body before finalizing uploads
    • Other modules only offer validation based on file size or metadata
    • Perfect for applications that require uploads on signup and those looking to save api requests
    • This makes efp faster for cloud storage as it can abort the file upload if you invalidate the request body
  • Pipes buffer streams to api endpoints making it a very fast and memory efficient file uploader

Installation

$ npm install express-form-post --save

Usage

The information for the uploaded file will be available in the files object in the request object. Fields that were sent along the request will be available on thebody object in the request object. express-form-post can be dropped in as middleware or used as a function to handle file upload. Check out the samples on the github repository for more specific usage!

Quick Start as express.js middleware

Errors from validations will be passed in as a paramter to next(err). Check out this sample of handling the errors sample

var express = require("express");
var app = express();
var efp = require("express-form-post");
var formPost = efp();
 
app.use(formPost.middleware());

Usage as an asynchronous function (express.js not required)

You can also use express-form-post's method 'upload' instead of the middleware method.

var express = require("express");
var app = express();
var efp = require("express-form-post");
var formPost = efp();
 
app.post("/upload", function(req, res, next) { 
    formPost.upload(req, res, function(err) {
        if(err) {
            console.log(err);
        }
        console.log("My files are located here:", req.files);
        res.redirect("/");
    });
}

Usage as a promise (express.js not required)

You can also specify a promise options in efp(opts) to use the upload method as a promise. For those that prefer using promises, this is definitely a viable option.

var express = require("express");
var app = express();
var efp = require("express-form-post");
var formPost = efp({
    promise: true
});
 
app.post("/upload", function(req, res, next) { 
    formPost.upload(req, res).then(() => {
        // add your response statements here
        console.log("The uploaded file information is located here:", req.files);
        res.redirect("/");
    }).catch((err) => {
        // add your catch statements here
    });
}

Usage with Disk Storage

var express = require("express");
var app = express();
var efp = require("express-form-post");
const formPost = efp({
    store: "disk",
    directory: path.join(__dirname, "tmp"),
    maxfileSize: 10000,
    filename: function(req, file, cb) {
        cb(Date.now() + "-" + "this is the file name");
    },
    validateFile: function(file, cb) {
        if(file.mimetype != "application/pdf") {
            return cb(false);
        }
        return cb();
    },
    validateBody: function(body, cb) {
        // validates password length before uploading file
        if(body.password.length > 7) {
            return cb(false);
        }
        cb();
    }
});
 
app.post("/upload", formPost.middleware(), function(req, res, next) {
    console.log("I just received files", req.files);
    res.send("Upload successful!");
});

Usage with aws-s3

$ npm install aws-sdk@2.56.0 --save
var express = require("express");
var app = express();
var efp = require("express-form-post");
const formPost = efp({
    store: "aws-s3",
    maxfileSize: 100000,
    filename: function(req, file, cb) {
        cb(file.originalname);
    },
    api: {
        accessKeyId: process.env.AWS_ACCESS_KEY_ID,
        secretAccessKey: process.env.secretAccessKey,
        bucketName: process.env.S3_BUCKET_NAME,
        ACL: "public-read"
    }
})
 
app.post("/upload", formPost.middleware(), function(req, res, next) {
    console.log("I just received files", req.files);
    res.send("Upload successful!");
});

Usage with dropbox

$ npm install dropbox-stream@1.1 --save
var express = require("express");
var app = express();
var efp = require("express-form-post");
const formPost = efp({
    store: "dropbox",
    filename: function(req, file, cb) {
        cb(file.originalname);
    },
    api: {
        accessToken: process.env.dropboxAccessToken
    }
});
 
app.use(formPost.middleware(function(err) {
    if(err) console.log(err);
    console.log("Here are my files", req.files);
}));

API

When initializing an instance of efp (express-form-post) you can provide it different options that will change the way efp handles your file uploads.

express-form-post([opts])

express-form-post accepts an "optional" options parameter list. Keep in mind all fields are OPTIONAL. If you don't provide any, the express-form-post api will take care of that using the default options.

Key Description Note
store The type of store 'aws-s3', 'disk', or 'dropbox'
directory The folder to which the file will be saved defaults to current directory
promise True if upload is to be used as a promise Optional field. Defaults to false
filename function to determine file save name defaults to the a unique 64 bit hash generated by hasha
maxfileSize Maximum Size of the uploaded file in bytes defaults to infiniti
minfileSize Minimum Size of the uploaded file in bytes defaults to 0
validateFile function to validate uploaded file takes params: file, callback, skip
validateBody function to validate the body of the request before storing the validated file takes params: body, callback, skip
api api configuration information (api keys) read further documentation for specifications

Validation

One of the advantages of using express-form-post to handle file uploads is the validation api. There are two (optional) validation methods available during setup: validateFile and validateBody.

If specifying a validation method property, you must call the callback or skip (for validateFile) or your file will go unhandled.

Both validate functions were designed to be an intuitive way to create conditional file handling. It doesn't matter how many times you call the callback or skip function, only the first occurrence will be used to determine validity.

Calling the callback without any arguments or passing in null or undefined will 'validate' the file for that validate function.

In order to invalidate a request/file upload, you pass in an error message in the callback function. Alternatively, you can pass in an error object or false, but a string works the same.

validateFile also allows you the option to skip or ignore a certain file. Simply, call the skip function.

Examples are listed below.

validateBody(body, callback, skip)

The validateBody method validates the request's body before sending off your file to the specified store. This is especially helpful for handling signups that require uploading some type of file (e.g a resume). For example, if the user signs up without filling in the proper fields, you can cancel the file upload (saves api requests and creates faster responses for errors). Here is an example with validating that a field called 'username' was sent.

const formPost = efp({
    validateBody: function(body, cb, skip) {
        if(file.fieldname != "validName") {
            skip(); // skipping a file if their fieldname is not "validName"
        }
        if(body.username == undefined) {
            return cb("Username is required");
        }
        cb();
    }
});

validateFile(file, callback, skip)

The validateFile method validates the file data itself.

  • Calling the callback with no arguments continues the upload.
  • Calling the callback with any argument will abort the upload process.
  • Calling the skip function will skip that particular file and continue the upload.

An example use case would be aborting the upload if the file is not a pdf and only accepting files of a particular fieldname. (That fieldname will be "validName" in this example)

const formPost = efp({
    validateFile: function(file, cb, skip) {
        if(file.fieldname != "validName") {
            skip(); // skipping a file if their fieldname is not "validName"
        }
        if(file.mimetype != "application/pdf") {
            cb("File needs to be a PDF"); // aborts the upload
        } else {
            cb(); // continues upload
        }
    }
});

Available storage methods

  • disk
  • aws s3
  • dropbox

Storage handlers

There are three different ways to handle form data with express-form-post. The three ways are available as methods in the instance of a express-form-post object.

upload(request, response[, callback])

This method is used inside routes as a function rather than middleware. This allows better readability and customizability. This function takes in three parameters : request, response, and an optional callback. The request and response object should be the ones provided by express.

middleware()

This method is used as middleware and provides a good layer of abstraction for file handling. Errors are passed in as an argument to next(err).

fields()

This method is used to only parse the fields and ignore the files. I would recommend against using this and to use body-parser instead, but fields is available for those who are not looking to download multiple modules that do the same.

Configuring cloud storage

Here are the different information you can input for each api storage. These options would go inside the api property of the options listed above.

aws-s3

Key Description Note
accessKeyId AWS access key id Optional if already set through aws.config.update. You can find it here : aws console
secretAccessKey secret key for aws Optional based on your s3 settings
bucketName The name of your bucket. Required
ACL Access control list Privacy control. Defaults to "private"

dropbox

Key Description Note
accessToken used by Dropbox to identify your app Required Check out the docs
clientId Dropbox client Id Optional
selectUser Specific user in a team box Optional

Samples

Samples are also available on the github page. Please take a look and reach out if you have any questions: github

install

npm i express-form-post

Downloadsweekly downloads

95

version

1.4.2

license

ISC

homepage

github.com

repository

Gitgithub

last publish

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