How to upload file/images using nodejs?

I am assuming you already have install NodeJS in your System, Just follow below simple steps


Install below module ?

npm install express

npm install fs

npm install body-parser

npm install multer

HTML Part?
Create a file upload.html and add below code in file.

        <form action="http://127.0.0.1:8081/file_upload" enctype="multipart/form-data" id="uploadForm" method="POST" onsubmit="return uploadForm()">
Upload File: <input name="file" size="50" type="file" />
            <br />
<input type="submit" value="Upload File" />
        </form>

Node JS Code create upload.js file and add below code.

var express = require('express');
var app = express();
var fs = require("fs");

var bodyParser = require('body-parser');
var multer  = require('multer');

app.use(express.static('public'));
app.use(bodyParser.urlencoded({ extended: false }));
var upload = multer({ dest: './tmp' });

app.get('/upload.html', function (req, res) {
   res.sendFile( __dirname + "/" + "upload.html" );
})

app.post('/file_upload', upload.single('file'), function (req, res) {
    console.log(req.file);
    
    
   var file = __dirname + "/public/upload/" + req.file.originalname;
   
   
   fs.readFile( req.file.path, function (err, data) {
      fs.writeFile(file, data, function (err) {
         if( err ){
            console.log( err );
            }else{
               response = {
                  message:'File uploaded successfully',
                  filename:req.file.originalname
               };
            }
         console.log( response );
         res.end( JSON.stringify( response ) );
      });
   });
})

var server = app.listen(8081, function () {
   var host = server.address().address
   var port = server.address().port
   
   console.log("Example app listening at http://%s:%s", host, port)
})

Question: Following are sample of file object in ?

 { fieldname: 'file',
  originalname: 'Desert.jpg',
  encoding: '7bit',
  mimetype: 'image/jpeg',
  destination: './tmp',
  filename: '3570feafa527690b90b972a1bf085bdd',
  path: 'tmp\\3570feafa527690b90b972a1bf085bdd',
  size: 845941 }

Create following empty folder?

/tmp

/public

/public\upload

Now Start the Node project?

node upload.js

Access the Web URL?

http://127.0.0.1:8081/upload.html

Select the File and click on Upload File?
It will show below simiar message

{"message":"File uploaded successfully","filename":"Desert.jpg"}

Question: What port we have used here?
We have used 8081 port, but you can change it by change in upload.js

Best Related Posts are Following:

1. Express JS - use res.sendFile - use EJS template - Set and Get Session data.
2. How to Create RESTful APIs in Node Js using Express JS and MongoDB.
3. How to use cookies with expressJS in node.js.
4. Express js Interview questions and answers.

What is a promise and how to use with mongoose?

Question: What is a promise?
A promise is an abstraction for asynchronous programming.
It's an object that proxies for the return value thrown by a function that has to do some asynchronous processing.


Question: How does promise work?
The Promise constructor takes a function (an executor) that will be executed immediately and passes in two functions: resolve , which must be called when the Promise is resolved (passing a result), and reject , when it is rejected (passing an error)


Question: Give example of promise work in mongoose?

User.update({id: 100}, {$inc: { views: 1 }}).limit(1).exec();

Here execute multiple function in one line is promise.


Question: How to setup mongoose with promise?

var mongoose = require('mongoose');
mongoose.Promise = require('bluebird');
mongoose.connect('mongodb://localhost:27017/dbname');
var db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function() {
    console.log("MongoDB connected Successfully.!");
});

Question: How to Add the data in mongoDb with mongoose?

//Ajax chat messages
var AjaxChatMessageSchema = mongoose.Schema({
    id: Number,
    userID: Number,
    userName: String,
    userRole: String,
    channel: String,
    dateTime: String,
    ip: String,
    text: String,
    status: String,
    vid: Number
}, {collection: 'ajax_chat_messages'});
var AjaxChatMessage = mongoose.model('ajax_chat_messages', AjaxChatMessageSchema);

var saveData={id:11, userName:'testuser',text:'hello user'}
var AjaxChatMessageDtls = new AjaxChatMessage(saveData);
AjaxChatMessageDtls.save(function(err) {
    if (err) {
        console.log("Error while saving the details");
        response.success = 0;
        res.send(response);
    } else {
        response.success = 1;        
        res.send(response);
    }
});

Question: How to do decrement the value by 1?

AjaxChatMessage.update({id: 100}, {$inc: { views: -1 }}).limit(1).exec();

Question: From where we can read more about promise?
http://mongoosejs.com/docs/promises.html

Best Related Posts are Following:

1. How to Create RESTful APIs in Node Js using Express JS and MongoDB.
2. Mongoose Tutorial - listing records, Add Record, update record and delete record.
3. Express js Interview questions and answers.