File uploads in FeathersJS
==========================

Over the last months we at `ciancoders.com <https://ciancoders.com/>`_
have been working in a new SPA project using Feathers and React, the
combination of those two turns out to be **just amazing**.

Recently we were struggling to find a way to upload files without having
to write a separate Express middleware or having to (re)write a complex
Feathers service.

Our Goals
---------

We want to implement an upload service to accomplish a few important
things:

1. It has to handle large files (+10MB).
2. It needs to work with the app’s authentication and authorization.
3. The files need to be validated.
4. At the moment there is no third party storage service involved, but
   this will change in the near future, so it has to be prepared.
5. It has to show the upload progress.

The plan is to upload the files to a feathers service so we can take
advantage of hooks for authentication, authorization and validation, and
for service events.

Fortunately, there exists a file storage service:
`feathers-blob <https://github.com/feathersjs/feathers-blob>`_. With it
we can meet our goals, but (spoiler alert) it comes with its own
problems which we’ll discuss below.

Basic upload with feathers-blob and feathers-client
---------------------------------------------------

For the sake of simplicity, we will be working over a very basic
feathers server, with just the upload service.

Lets look at the server code:

.. code:: javascript

   /* --- server.js --- */

   const feathers = require('@feathersjs/feathers');
   const express = require('@feathersjs/express');
   const socketio = require('feathers-socketio');

   // feathers-blob service
   const blobService = require('feathers-blob');
   // Here we initialize a FileSystem storage,
   // but you can use feathers-blob with any other
   // storage service like AWS or Google Drive.
   const fs = require('fs-blob-store');
   const blobStorage = fs(__dirname + '/uploads');


   // Feathers app
   const app = express(feathers());

   // Parse HTTP JSON bodies
   app.use(express.json());
   // Parse URL-encoded params
   app.use(express.urlencoded({ extended: true }));
   // Add REST API support
   app.configure(express.rest());
   // Configure Socket.io real-time APIs
   app.configure(socketio());


   // Upload Service
   app.use('/uploads', blobService({Model: blobStorage}));


   // Register a nicer error handler than the default Express one
   app.use(express.errorHandler());

   // Start the server
   app.listen(3030, function(){
       console.log('Feathers app started at localhost:3030')
   });

Let’s look at this implemented in the ``@feathersjs/cli`` generated
server code:

.. code:: javascript

   /* --- /src/services/uploads/uploads.service.js --- */

   // Initializes the `uploads` service on path `/uploads'


   // Here we used the nedb database, but you can
   // use any other ORM database.
   const createService = require('feathers-nedb');

   const createModel = require('../../models/uploads.model');
   const hooks = require('./uploads.hooks');
   const filters = require('./uploads.filters');


   // feathers-blob service
   const blobService = require('feathers-blob');
   // Here we initialize a FileSystem storage,
   // but you can use feathers-blob with any other
   // storage service like AWS or Google Drive.
   const fs = require('fs-blob-store');


   // File storage location. Folder must be created before upload.
   // Example: './uploads' will be located under feathers app top level.
   const blobStorage = fs('./uploads');

   module.exports = function() {
     const app = this;
     const Model = createModel(app);
     const paginate = app.get('paginate');

     // Initialize our service with any options it requires
     app.use('/uploads', blobService({ Model: blobStorage}));

     // Get our initialized service so that we can register hooks and filters
     const service = app.service('uploads');

     service.hooks(hooks);

     if (service.filter) {
       service.filter(filters);
     }
   };

``feathers-blob`` works over abstract-blob-store, which is an abstract
interface to various storage backends, such as filesystem, AWS, or
Google Drive. It only accepts and retrieves files encoded as dataURI
strings.

Just like that we have our backend ready, go ahead and POST something to
localhost:3030/uploads`, for example with postman:

.. code:: json

   {
       'uri': 'data:image/gif;base64,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'
   }

The service will respond with something like this:

.. code:: json

   {
     'id': '6454364d8facd7a88e627e4c4b11b032d2f83af8f7f9329ffc2b7a5c879dc838.gif',
     'uri': 'the-same-uri-we-uploaded',
     'size': 1156
   }

Or we can implement a very basic frontend with ``feathers-client`` and
``jQuery``:

.. code:: html

   <!doctype html>
   <html>
       <head>
           <title>Feathersjs File Upload</title>
           <script   src='https://code.jquery.com/jquery-2.2.3.min.js'   integrity='sha256-a23g1Nt4dtEYOj7bR+vTu7+T8VP13humZFBJNIYoEJo='   crossorigin='anonymous'></script>
           <script type='text/javascript' src='//cdnjs.cloudflare.com/ajax/libs/core-js/2.1.4/core.min.js'></script>
           <script type='text/javascript' src='//unpkg.com/feathers-client@^2.0.0/dist/feathers.js'></script>
           <script type='text/javascript'>
               // feathers client initialization
               const rest = feathers.rest('http://localhost:3030');
               const app = feathers()
               .configure(feathers.hooks())
               .configure(rest.jquery($));

               // setup jQuery to watch the ajax progress
               $.ajaxSetup({
                   xhr: function () {
                       var xhr = new window.XMLHttpRequest();
                       // upload progress
                       xhr.addEventListener('progress', function (evt) {
                           if (evt.lengthComputable) {
                               var percentComplete = evt.loaded / evt.total;
                               console.log('upload progress: ', Math.round(percentComplete * 100) + '%');
                           }
                       }, false);
                       return xhr;
                   }
               });

               const uploadService = app.service('uploads');
               const reader  = new FileReader();

               // encode selected files
               $(document).ready(function(){
                   $('input#file').change(function(){
                       var file = this.files[0];
                       // encode dataURI
                       reader.readAsDataURL(file);
                   })
               });

               // when encoded, upload
               reader.addEventListener('load', function () {
                   console.log('encoded file: ', reader.result);
                   var upload = uploadService
                       .create({uri: reader.result})
                       .then(function(response){
                           // success
                           alert('UPLOADED!! ');
                           console.log('Server responded with: ', response);
                       });
               }, false);
           </script>
       </head>
       <body>
           <h1>Let's upload some files!</h1>
           <input type='file' id='file'/>
       </body>
   </html>

This code watches for file selection, then encodes it and does an ajax
post to upload it, watching the upload progress via the xhr object.
Everything works as expected.

Every file we select gets uploaded and saved to the ``./uploads``
directory.

Work done!, let’s call it a day, shall we?

… But hey, there is something that doesn’t feels quite right …right?

DataURI upload problems
~~~~~~~~~~~~~~~~~~~~~~~

It doesn’t feels right because it is not. Let’s imagine what would
happen if we try to upload a large file, say 25MB or more: The entire
file (plus some extra MB due to the encoding) has to be kept in memory
for the entire upload process, this could look like nothing for a normal
computer but for mobile devices it’s a big deal.

We have a big RAM consumption problem. Not to mention we have to encode
the file before sending it…

The solution would be to modify the service, adding support for
splitting the dataURI into small chunks, then uploading one at a time,
collecting and reassembling everything on the server. But hey, it’s not
that the same thing browsers and web servers has been doing since maybe
the very early days of the web? maybe since Netscape Navigator?

Well, actually it is, and doing a ``multipart/form-data`` post is still
the easiest way to upload a file.

Feathers-blob with multipart support.
-------------------------------------

Back with the backend, in order to accept multipart uploads, we need a
way to handle the ``multipart/form-data`` received by the web server.
Given that Feathers behaves like Express, let’s just use ``multer`` and
a custom middleware to handle that.

.. code:: javascript

   /* --- server.js --- */
   const multer = require('multer');
   const multipartMiddleware = multer();

   // Upload Service with multipart support
   app.use('/uploads',

       // multer parses the file named 'uri'.
       // Without extra params the data is
       // temporarely kept in memory
       multipartMiddleware.single('uri'),

       // another middleware, this time to
       // transfer the received file to feathers
       function(req,res,next){
           req.feathers.file = req.file;
           next();
       },
       blobService({Model: blobStorage})
   );

Notice we kept the file field name as *uri* just to maintain uniformity,
as the service will always work with that name anyways. But you can
change it if you prefer.

Feathers-blob only understands files encoded as dataURI, so we need to
convert them first. Let’s make a Hook for that:

.. code:: javascript

   /* --- server.js --- */
   const dauria = require('dauria');

   // before-create Hook to get the file (if there is any)
   // and turn it into a datauri,
   // transparently getting feathers-blob to work
   // with multipart file uploads
   app.service('/uploads').before({
       create: [
           function(context) {
               if (!context.data.uri && context.params.file){
                   const file = context.params.file;
                   const uri = dauria.getBase64DataURI(file.buffer, file.mimetype);
                   context.data = {uri: uri};
               }
           }
       ]
   });

*Et voilà!*. Now we have a FeathersJS file storage service working, with
support for traditional multipart uploads, and a variety of storage
options to choose.

**Simply awesome.**

Further improvements
--------------------

The service always return the dataURI back to us, which may not be
necessary as we’d just uploaded the file, also we need to validate the
file and check for authorization.

All those things can be easily done with more Hooks, and that’s the
benefit of keeping all inside FeathersJS services. I left that to you.

For the frontend, there is a problem with the client: in order to show
the upload progress it’s stuck with only REST functionality and not
real-time with socket.io.

The solution is to switch ``feathers-client`` from REST to
``socket.io``, and just use wherever you like for uploading the files,
that’s an easy task now that we are able to do a traditional
``form-multipart`` upload.

Here is an example using dropzone:

.. code:: html

   <!doctype html>
   <html>
       <head>
           <title>Feathersjs File Upload</title>

           <link rel='stylesheet' href='assets/dropzone.css'>
           <script src='assets/dropzone.js'></script>

           <script type='text/javascript' src='socket.io/socket.io.js'></script>
           <script type='text/javascript' src='//cdnjs.cloudflare.com/ajax/libs/core-js/2.1.4/core.min.js'></script>
           <script type='text/javascript' src='//unpkg.com/feathers-client@^2.0.0/dist/feathers.js'></script>
           <script type='text/javascript'>
               // feathers client initialization
               var socket = io('http://localhost:3030');
               const app = feathers()
               .configure(feathers.hooks())
               .configure(feathers.socketio(socket));
               const uploadService = app.service('uploads');

               // Now with Real-Time Support!
               uploadService.on('created', function(file){
                   alert('Received file created event!', file);
               });


               // Let's use DropZone!
               Dropzone.options.myAwesomeDropzone = {
                   paramName: 'uri',
                   uploadMultiple: false,
                   init: function(){
                       this.on('uploadprogress', function(file, progress){
                           console.log('progresss', progress);
                       });
                   }
               };
           </script>
       </head>
       <body>
           <h1>Let's upload some files!</h1>
           <form action='/uploads'
             class='dropzone'
             id='my-awesome-dropzone'></form>
       </body>
   </html>

All the code is available via github here:
https://github.com/CianCoders/feathers-example-fileupload

Hope you have learned something today, as I learned a lot writing this.

Cheers!