Async functionality not functioning

Question

I have my express code below

What i am doing::

1. I am renaming the location of the image i receive on the server
2. I am also updating the name of the image to database
3. I am doing both the things simoultaniously
4. I am using async for this

---

My Problem::

• So there are two call backs in async in the program
• Only my first callback functionality works and the other one is not working
• Though i have defined both the tasks perfectly fine still, handling them at a time, i am not able to resolve it

---

app.js

var express=require('express');
var fs=require('fs');
var http=require('http');
var crypto=require('crypto');
var mysql=require('mysql');
var async=require('async');

var app=express();

var connection=mysql.createConnection({
    host: 'localhost',
    user: 'root',
    database: 'ImagePostingDB'
});

connection.connect();
app.set('port',process.env.PORT||7002); 
app.use('/Details',express.static(__dirname+'/public/images')); 
app.use(express.bodyParser());

app.post('/Details/',function(req,res,next)
{
    var file_name=req.files.key.originalFilename;
    console.log(file_name);
    async.series( [
       // Get the first table contents
       function ( callback ) 
       {
          crypto.randomBytes(8, function(ex, buf) {

                var array     = req.files.key.originalFilename.split('.');
                var type      = array[array.length - 1];
                var name      = buf.toString('hex') + '.' + type;

                fs.rename(req.files.key.path, './public/images/' + name, function(e) {


                        if (e) {
                                res.send(500, e.message);
                                } else 
                                {
                                    res.send("I got the message - This i confirm");
                                }

                });
            });
       },
       // Updating the database
       function ( callback ) 
       {

            connection.query('INSERT INTO ImagePostingTABLE (Image_Name) VALUES (?)', [file_name], function (err, rows, fields)
            {
                console.log('Connection result error ' + err);
            });
       }
    ] );
});

app.get('/Details/',function(req,res){
        res.send("Image displayed");
});

http.createServer(app).listen(app.get('port'),function(){
        console.log('Express server listening on port'+app.get('port'));

});

---

How can i resolve this

Hope i am clear

Answer 1

With the help of C Blanchard & Bulkan ..... i got solution for this

---

Here is the complete solution :: This may help someone looking something similar

var express=require('express');

    var fs=require('fs');
    var http=require('http');
    var crypto=require('crypto');
    var mysql=require('mysql');
    var async=require('async');

    var app=express();

    var connection=mysql.createConnection({
        host: 'localhost',
        user: 'root',
        database: 'ImagePostingDB'
    });

    connection.connect();
    app.set('port',process.env.PORT||7002); 
    app.use('/Details',express.static(__dirname+'/public/images')); 
    app.use(express.bodyParser());

    app.post('/Details/',function(req,res,next) {
      var file_name=req.files.key.originalFilename;

      console.log(file_name);
      async.series( [
        // Get the first table contents
        function ( callback ) {
          crypto.randomBytes(8, function(ex, buf) {

            var array = req.files.key.originalFilename.split('.');
            var type  = array[array.length - 1];
            var name  = buf.toString('hex') + '.' + type;

            fs.rename(req.files.key.path, './public/images/' + name, function(e) {

              if (e) {
                res.send(500, e.message);
              } else {
                res.send("I got the message - This i confirm");
              }

              return callback(null);
            });
          });
        },
        // Updating the database
        function ( callback ) {
          connection.query('INSERT INTO ImagePostingTABLE (Image_Name) VALUES (?)', [file_name], function (err, rows, fields) {
            console.log('Connection result error ' + err);
            return callback(null);
          });
        }
      ]);
    });

    app.get('/Details/',function(req,res){
            res.send("Image displayed");
    });

    http.createServer(app).listen(app.get('port'),function(){
            console.log('Express server listening on port'+app.get('port'));

    });

Answer 2

Please read the documentation on the Async's series method (click here)

In order to move to the next function in the series, the callback needs to be invoked

async.series([
  function(callback){
    crypto.randomBytes(8, function(ex, buf) {
      var array     = req.files.key.originalFilename.split('.');
      var type      = array[array.length - 1];
      var name      = buf.toString('hex') + '.' + type;
      fs.rename(req.files.key.path, './public/images/' + name, function(e) {
        if (e) {
          res.send(500, e.message);
        } else {
          res.send("I got the message - This i confirm");
        }
        callback(null); // Pass whatever you think is appropriate
      });
    });
  },
  function(callback){
      connection.query('INSERT INTO ImagePostingTABLE (Image_Name) VALUES (?)', [file_name], function (err, rows, fields) {
          console.log('Connection result error ' + err);
          callback(err, rows)
        });
  }
]);

Answer 3

You need to call the callback that is passed to the task functions of async.series Here is the code

app.post('/Details/',function(req,res,next) {
  var file_name=req.files.key.originalFilename;

  console.log(file_name);
  async.series( [
    // Get the first table contents
    function ( callback ) {
      crypto.randomBytes(8, function(ex, buf) {

        var array = req.files.key.originalFilename.split('.');
        var type  = array[array.length - 1];
        var name  = buf.toString('hex') + '.' + type;

        fs.rename(req.files.key.path, './public/images/' + name, function(e) {

          if (e) {
            res.send(500, e.message);
          } else {
            res.send("I got the message - This i confirm");
          }

          return callback(null);
        });
      });
    },
    // Updating the database
    function ( callback ) {
      connection.query('INSERT INTO ImagePostingTABLE (Image_Name) VALUES (?)', [file_name], function (err, rows, fields) {
        console.log('Connection result error ' + err);
        return callback(null);
      });
    }
  ]);
});