unable to return variable in node.js

Question

i'm returning the variable uploadFile from my function and when I'm trying to access it in another variable it gives me undefined

function upload(req, res, callback) {
    var dir = 'uploads/';

    if (!fs.existsSync(dir)) {
        fs.mkdirSync(dir);
    }

    console.log(req.files.file1);
    console.log(req.files.file2);

    var uploadFiles = {
        ext1: path.extname(req.files.file1.originalname),
        path1: req.files.file1.path,
        ext2: path.extname(req.files.file2.originalname),
        path2: req.files.file2.path
    }
    return callback(uploadFiles);
}

this is the function where I'm calling the upload function I guess I'm doing it the wrong way, I'm getting Callback is not a function as the error ... please guide me

function sendMail(req, res) {
    var data = req.body;
     upload(req,res);
// checking the condition if the file has been uploaded
    if (uploadFiles) {
        data_to_send.attachments = [{
            filename: 'file1' + uploadFiles.file1ext,
            filePath: uploadFiles.file1Path 
        }, {
            filename: 'file2' + uploadFiles.file2ext,
            filePath: uploadFiles.file2Path
        }]
    }
    console.log(data_to_send.attachments)
    smtpTransport.sendMail({
            from: data_to_send.from,
            to: data_to_send.to,
            subject: data_to_send.subject,
            atachments: data_to_send.attachments,
            text: data_to_send.text,
            html: data_to_send.html
        },
//.........

this [post](http://stackoverflow.com/questions/23691194/node-express-file-upload) help you — Shayan, Apr 23 '16 at 08:20
Maybe your hitting an exception, try wrapping the whole function in a try/catch and see if anything gets caught. — utamanna, Apr 23 '16 at 08:32
looks like you should not get undefined. how to you get back the value and use it? — nonopolarity, Apr 23 '16 at 08:49
even though I'm doing console(uploadFiles) in another function, I'm getting undefined — Ankit Kumar, Apr 23 '16 at 09:16
what about trying to call a callback? Say `function upload(req, res, cb) { //logic .. }` then call `cb(uploadFiles)` at the end of the function? — ArchNoob, Apr 23 '16 at 21:10
How can I use that callback in another function to check a condition if uploadFiles exists — Ankit Kumar, Apr 24 '16 at 07:50

score 2 · Accepted Answer · answered Apr 24 '16 at 11:47

The problem is that in your upload function you are not checking that callback was actually passed (and not undefined). Also, you are not returning your values, you are actually returning whatever callback is returning.

Here is some code that might help you:

// inside your upload function
var uploadFiles = {
        ext1: path.extname(req.files.file1.originalname),
        path1: req.files.file1.path,
        ext2: path.extname(req.files.file2.originalname),
        path2: req.files.file2.path
    }
if (callback) {
    callback(uploadFiles);
}

//inside your sendMail (notice the 3rd parameter passed to upload)
upload(req, res, function (uploadFiles) {
    if (uploadFiles) {
        data_to_send.attachments = [{
            filename: 'file1' + uploadFiles.file1ext,
            filePath: uploadFiles.file1Path 
        }, {
            filename: 'file2' + uploadFiles.file2ext,
            filePath: uploadFiles.file2Path
        }]
    }
    // rest of the code goes here, inside the callback.
});

Now you will actually receive your files in the callback, as you wanted.

thanks that was helpful , I really need to learn more about coding and javascript . Can u please invite me for a chat so that I can learn more from you — Ankit Kumar, Apr 24 '16 at 12:05

score -2 · Answer 2 · edited May 23 '17 at 11:45

-2

This is a scoping issue. You can't call uploadFiles in another function because you are defining it in upload. You can try defining it outside of upload, or you can try console(upload(params you are passing in)). Option three, I am completely mistaken by what you are asking.

Here is a good reference to scoping in Javascript: What is the scope of variables in Javascript?

edited May 23 '17 at 11:45

Community

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1

answered Apr 23 '16 at 21:03

Andrew Moon

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Misconception, he is not accessing the variable he is accessing the returned data (in that case uploadFiles variable) .. – ArchNoob Apr 23 '16 at 21:07

unable to return variable in node.js

2 Answers2