How to upload data in nodejs

Node.js is an efficient server-side JavaScript interpreter commonly used to build high-performance, scalable and extensible web applications. In Node.js, uploading data is one of the common tasks, which is mainly achieved through HTTP requests and file uploads.

This article will introduce how to implement the method of uploading data in Node.js, including uploading files and uploading form data.

1. Node.js upload files

In Node.js, uploading files through the multipart/form-data form is a common method. This approach allows us to upload files of different types and sizes and store them on the server side. The following is a simple example of uploading files:

const http = require('http');
const fs = require('fs');
const formidable = require('formidable');

http.createServer(function (req, res) {
    if (req.url == '/upload' && req.method.toLowerCase() == 'post') {
        var form = new formidable.IncomingForm();
        form.parse(req, function (err, fields, files) {
            var oldpath = files.filetoupload.path;
            var newpath = 'C:/Users/Username/' + files.filetoupload.name;
            fs.rename(oldpath, newpath, function (err) {
                if (err) throw err;
                res.write('File uploaded and moved!');
                res.end();
            });
        });
    } else {
        res.writeHead(200, {'Content-Type': 'text/html'});
        res.write('<form action="upload" method="post" enctype="multipart/form-data">');
        res.write('<input type="file" name="filetoupload"><br>');
        res.write('<input type="submit">');
        res.write('</form>');
        return res.end();
    }
}).listen(8080);

The above code uses the formidable module in Node.js, which can help us process uploaded files. In this code, we create a server and listen to an address. When uploading files, we call the IncomingForm() method of formidable and parse the uploaded data through the parse() method.

After the upload is successful, move the temporary path of the file (oldpath) to the new path (newpath), and throw an exception if there is an error.

2. Upload form data with Node.js

In Node.js, if you do not need to upload files but only need to upload form data, you can use the following method:

const http = require('http');

http.createServer(function (req, res) {
    if (req.url == '/upload' && req.method.toLowerCase() == 'post') {
        var body = '';
        req.on('data', function (data) {
            body += data;
        });
        req.on('end', function () {
            var post = qs.parse(body);
            console.log(post);
            res.writeHead(200, {'Content-Type': 'text/plain'});
            res.end('ok');
        });
    } else {
        res.writeHead(200, {'Content-Type': 'text/html'});
        res.write('<form action="upload" method="post">');
        res.write('<input type="text" name="name"><br>');
        res.write('<input type="text" name="age"><br>');
        res.write('<input type="submit">');
        res.write('</form>');
        return res.end();
    }
}).listen(8080);

The above code uses the http and querystring built-in modules of Node.js. In this example, we create a server and listen on an address to handle requests for form data. When we submit the form data, the request will be sent to the server, and the server will listen to the event of the request data through the on() method and use the querystring module to parse the request data.

In this example, we simply parse the form data and print the results to the console. In practical applications, we may need to store these data in a database or send them to other places for processing.

Summary

This article mainly introduces how to upload data in Node.js, including uploading files and uploading form data. When uploading files, you need to use the multipart/form-data form, but uploading form data does not require uploading files. You only need to include the form field names and field values ​​in the request data. By learning these methods, we can better handle the need to upload data in Node.js.

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