Writing a serverless method that uploads documents:

Description: One of the most common techniques for uploading documents involves a form submission from the FrontEnd application. The user points to a file at a location specified by a folder on her computer and the client-side script in the frontend reads the file as a stream. When the same file content needs to be made available to the middleware, HTTP based methods struggle with the right way to send the data.

The key to send the data is to specify it as a multipart/form-data. This is the most efficient content-type for sending binary data to the server. Multiparts means that data is sent to the server in separate parts. Each of the components may have a different content type, file name and data. The data are separated from each other by a boundary string. When a command line tool like curl sends this request , it does so as a multipart request with a specially formatted POST message body and a series of parts separated by MIME boundaries

For example,

POST /echo HTTP/1.1

Content-Type: multipart/form-data; boundary=---WD9543A

Content-Length: 100

---WD9543A

Content-Disposition: form-data; name=”user-name”

John

---WD9543A

Content-Disposition: form-data; name=”text-data”;

filename=”user.txt”

Content-Type: text/plain

[Text-Data]

---WD9543A

When the controller receives this request, it can refer directly to the parts as follows:

Request.body.name

And

Request.file

For example:

Const multer = require(‘multer’)

Const upload = multer({ dest: os.tmpdir()});

Router.post(‘/upload’, upload.single(file), function (req, res) {

const title = req.body.title;

const file = req.file;

console.log(title);

console.log(file);

res.sendStatus(200);

});