ASYNC issue on node.js

Question

I'm new to node and I tried to make a basic app with authentification . Data are stored on a mongoDB remote server. My HTML form POST data to my server URL. Here the route :

app.post('/auth', function(req, res){
handleRequest(req, res);

});

And the called handler :

function handleRequest(request, response) {
    if (request.method == 'POST') {
        console.log("Trying to get POST");
        var body = '';
        request.on('data', function (data) {
            body += data;
        });

        // Get datas, parse them and create user with it
        request.on('end', function () {
            var data = JSON.parse(body);
            var login = data.login;
            var password = data.password;
            var email = data.email;

            myUser = userClass.create(login,email,password);

            console.log ("email : "+email);
            console.log ("password : "+password);


            // authenticate with user
            var auth = userClass.authenticate(myUser,function(result){
                console.log("result = "+result);
                    });

             });
    }
}

The userClass.authenticate :

exports.authenticate = function(user,callback){
    var result = "false";
    var query = User.where(
    { 
        email : user.email,
        password : user.password

    });
    query.findOne(function(err,user){
        if(err){return handleError(err);}
        if(user){
            result = "true";
        }
        console.log(user);
    });
    console.log("callback inc")
    callback(result);
}

I'm pretty sure it's not optimized but it's not what I'm looking for. When I launch the server and I send it some POST (correct) data, this strange thing happens :

My user stored in remote DB is found , so in userClass.authenticate result = true But when the callback function is ran, the log say it's false. Did I do a something wrong in the callback ?

Jaromanda X · Accepted Answer · 2015-11-21 01:27:28Z

1

if query.findOne is Asynchronous, you're calling the callback before findOne is complete. Put the callback(result) inside the findOne callback - like this

exports.authenticate = function(user,callback){
    var result = "false";
    var query = User.where(
    { 
        email : user.email,
        password : user.password

    });
    query.findOne(function(err,user){
        if(err){return handleError(err);}
        if(user){
            result = "true";
        }
        console.log(user);
        callback(result);
    });
}

answered Nov 21, 2015 at 1:27

Jaromanda X

1

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2 Comments

Azrael_404 Over a year ago

That's a point I didn't saw before. Callback calls must been done inside the calling function ? Thx for fast response, I mark as solved in 2 mins

Jaromanda X Over a year ago

Callback calls must been done inside the calling function in this case, yes, because findOne is asynchronous, you wont have a value until the findOne callback is called, so it's in this callback you call your callback

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