NodeJS - call a method after another method is fully executed

Calling a function with callback method

delete_chat_message(messageId,function(result){            
    if(result.success){
        console.log('Chat message is deleted successfully.');
    }else{
        console.log('Unable to delete Chat message.');
    }
});

Function Definition with callback execution

    delete_chat_message=function(messageId, calbackFunc){
    var results = {success: 0, id: messageId}
    
        /* Model to delete the chat message*/
        AjaxChatMessage.remove({id: messageId}, function(err, data) {
            console.log('here');
            if (err) {
                results.success = 0;
            }else{
                results.success = 1;
            }
            //call the callback function
            calbackFunc(results);
        }); 
    }

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.