NodeJS: 'multer' file upload callback function - node.js

Question

I am using 'multer' plugin for file upload. I want to call another function after file upload successfully.
Here my code:
module.exports.uploadFile = upload.single('file', '_id'), function (req, res, next) {
console.log('Uploade Successful');
}
var upload = multer({
storage: multer.diskStorage({
destination: './Media/ChatDocUpload',
filename: function (req, file, cb) {
var dest = './Media/ChatDocUpload';
//query string params
var _chatMessageID = req.query.chatMessageID;
var _ext = file.originalname.substring(file.originalname.indexOf("."));
var _fileName = _chatMessageID + _ext;
cb(null, _fileName);
}
})
});
I want to call my new function after image uploaded. Using this code i can upload image successfully, but not get call callback function.
I need call new function after image uploading completed.
//I need to call this function after image fully uploaded
var uploadSuccessFn = function () {
//code
}

Answer 1

You could maybe change the code to use 2 functions in your POST handler:
module.exports = {uploadFile: uploadFile, afterUpload: afterUpload};
function uploadFile(){
upload.single('file', '_id');
}
function afterUpload(req, res, next) {
console.log('Uploade Successful');
}
var upload = multer({
storage: multer.diskStorage({
destination: './Media/ChatDocUpload',
filename: function (req, file, cb) {
var dest = './Media/ChatDocUpload';
//query string params
var _chatMessageID = req.query.chatMessageID;
var _ext = file.originalname.substring(file.originalname.indexOf("."));
var _fileName = _chatMessageID + _ext;
cb(null, _fileName);
}
})
});
Then simply require the file and use it in the post request handler:
.
.
var imageUpload = require('./handler');
app.post('/image/upload',imageUpload.uploadFile,imageUpload.afterUpload);
.
.

Answer 2

The function (inside the process) when you are calling the process of upload, is the callback fuction just use it . you are written line console.log it means your callback fuction is called when your file is upload but you are not using ..
can be done like this:-
function(req,res){ //callback function
res.json({message:"file uploaded successfully"});
}
it will give you json response.

Answer 3

I suggest that you create your own customized storage engine based on multer:
Multer Storage Engine
Then you just add the customized code after your file has been uploaded. Something like this:
MyCustomStorage.prototype._handleFile = function _handleFile (req, file, cb) {
this.getDestination(req, file, function (err, path) {
if (err) return cb(err)
var outStream = fs.createWriteStream(path)
file.stream.pipe(outStream)
outStream.on('error', cb)
outStream.on('finish', function () {
// Insert here whatever you want to do...
console.log('Successfully Uploaded');
cb(null, {
path: path,
size: outStream.bytesWritten
})
}) })}
Please note that you have to use var fs = require('fs') to make it work. Hope this help.

Answer 4

In your code from where you calling upload put an if condition which checks the checks the callback response. If response null then you can call another function in that condition else show some error.
I guess the function you trying call will show some kind of success message to the user.

Answer 5

try like this
var storage = multer.diskStorage({
destination: function (req, file, cb) {
return cb(null, './Media/ChatDocUpload')
},
filename: function (req, file, cb) {
var _chatMessageID = req.query.chatMessageID;
var _ext = file.originalname.substring(file.originalname.indexOf("."));
var _fileName = _chatMessageID + _ext;
return cb(null, _fileName);
}
})
var upload = multer({ storage: storage })
module.exports.uploadFile = upload.single('file'), function (req, res, next) {
console.log('Uploade Successful');
// you function after uploading images
}