Develop Reference

What would be necessary to code the callback function to receive the access token?

I am trying to retrieve the access token from an API (https://github.com/Axosoft/node-axosoft/)
To receive an access token we have to follow this process:
var axo = nodeAxosoft(axosoftUrl, credentials);
axo.Api.getLoginUrl(function(url) {
// open browser using authorizationUrl and get code parameter from
//redirected Url after login
var code = 'code received from redirect';
axo.Api.exchangeCodeForToken(code);
});
As I did not understood exactly how to get the code following that example nor what is the url parameter on getLoginUrl, I did it on my own.
I have a login route that redirects the user to the axosoft website for authentication and redirects the user to the /authorization-process route on my application.
On the /authorization-process I get the code returned by the login and call a function that should get the access token by calling:
axo.Api.exchangeCodeForToken(code);
Code:
var axosoft_code = req.query.code;
console.log(axosoft_code);
var token = request.exchangeAuthCodeForAccessToken(axosoft_code)
.then(function(token)
{
res.send(token);
})
The Method:
var connection = nodeAxosoft(client_url, credentials);
return new Promise(function(resolve, reject){
console.log("CODE: ", axosoft_code)
var token = connection.Api.exchangeCodeForToken(axosoft_code, function(token){
console.log(token);
resolve(token)
})
The problem is that returns null
I had a look at the API lib api.js and found that:
https://github.com/Axosoft/node-axosoft/blob/master/lib/api.js
function exchangeCodeForToken(code, callback) {
_credentials.code = code;
_access_token = '';
_authenticateCredentails(function (err) {
if (!err) {
callback(null, _access_token);
} else {
callback(err);
}
})
}
So I have two questions:
Does anyone has an Idea what am I doing wrong?
What would be necessary to code the callback function?
The method expects a callback function but I don't really know how to do it.
EDIT:
return new Promise(function(resolve, reject){
var token = connection.Api.exchangeCodeForToken(axosoft_code, function(response,err){
if(!err){
console.log("token",response)
resolve(token);
}
else{
console.log("error",err)
resolve(token);
}
});
})
OR
var token = connection.Api.exchangeCodeForToken(axosoft_code, function(response,err){
if(!err){
console.log("token",response.body)
return response.body;
}
else{
console.log("error",err)
return err;
}
});
I am giving to my callback function two args (response and err), my problem is that I am falling at the else condition.
The output of err is something similar to a token though the documentation here shows that it should be like that:
{
"error" : "invalid_request",
"error_description" : "One or more parameters are missing: client_secret"
}
Another point is that the page is frozen waiting for something to happen but nothing happens.

Given that this is the input:
function exchangeCodeForToken(code, callback) {
_credentials.code = code;
_access_token = '';
_authenticateCredentails(function (err) {
if (!err) {
callback(null, _access_token);
} else {
callback(err);
}
})
}
You should format your call as:
exchangeCodeForToken(axosoft_code, function(err, response) {
if (err) {
// Deal with error
} else {
// Deal with response
}
}
Node functions often pass through error variables first so that you have to receive them, which is considered good practice.

callback is not a function in node js

I am trying a simple operation that will result the particular users details from the database. Pooling database and all other connections work perfectly but the callback is not working. Am I doing anything wrong here?
Below is the code I use.
db_crud.js
var express = require('express');
var app = express();
var crud = require('./routes/crud_op_new.js');
var search = require('./routes/search.js');
var connection;
var result;
app.get('/search',(req,res)=>{
crud.connection(function (con) {
search.getuser(con,req.param('name'),result);
res.send(result);
});
});
app.listen(8003);
Finally here is where the error occurs ... search.js
exports.getuser = function(connection,req,callback){
console.log("GET Request iniciated");
connection.query("select * from user,addr where name=? and user.id=addr.e_id",[req],(err,row)=>{
if(err){
callback("DB ERROR: "+err);
}
else {
if(row.length==0){
callback("No Records found");
}
else {
callback(row);
}
}
});
}
The db_crud will send the credentials to search.js and here the callback is called to send result. crud_op_new.js creates the db pool connection and is in variable con.

As mentioned by Jaromanda X in the answer, result is just declared and unassigned which should be a callback function.
Also, the callback in search.js is being returned the error and result both as the first argument. You have to change this callback(row) to callback(null, row) to handle the error and result as below.
Note: Best practice in node js callback function would be, first argument
should return an error (null in case of no error) and then remaining arguments can be the return
values.
db_crud.js
var express = require('express');
var app = express();
var crud = require('./routes/crud_op_new.js');
var search = require('./routes/search.js');
var connection;
app.get('/search',(req,res)=>{
crud.connection(function (con) {
search.getuser(con,req.param('name'), function(err, result) {
if(err) {
res.status(501).send(err);
} else {
res.send(result);
}
});
});
});
app.listen(8003);
search.js
exports.getuser = function(connection,req,callback){
console.log("GET Request iniciated");
connection.query("select * from user,addr where name=? and user.id=addr.e_id",[req],(err,row)=>{
if(err){
callback("DB ERROR: "+err);
}
else {
if(row.length==0){
callback("No Records found");
}
else {
callback(null, row);
}
}
});
}

you call your function search.getuser(con,req.param('name'),result); ... result is not a function, it's undefined ... a callback needs to be a function so it can be called back
This should work
app.get('/search',(req,res)=>{
crud.connection(function (con) {
// vvvvvvvvvvvvvvv this is the callback function
search.getuser(con,req.param('name'),function(result) {
res.send(result);
});
});
});

async watefall doesn't call the functions

So i am actually woking on a simple program with node.Js and i have an issue using async.waterfall :
I created a function in my user model that connect the user by accessing the database, here is the code :
exports.connection = function (login,password) {
async.waterfall([
function getLogin(callback){
usersModel.findOne({ login: login }, function (err, res) {
if (err){
callback(err,null);
return;
}
if(res != null ){
// test a matching password if the user is found we compare both passwords
var userReceived = res.items[0].login;
callback(null,userReceived);
}
});
},
function getPassword(userReceived, callback){
console.log(userReceived);
callback(null,'done')
}
], function(err){
if (err) {
console.error(err);
}
console.log('success');
});
}
Using node-inspector i figured out that the main issue(I think) is that when it enters the waterfall function it doesn't execute the callback function of findOne it literally skips this and directly jump to the getPassword function (which isn't executed too).
so if someone could help me figuring out what's the problem that would be nice since i'm on it for around two days now.
Thank you
EDIT:
After adding the different missing cases of tests(which was why the callback didn't worked) I have this connection function:
exports.connection = function (login,password) {
async.waterfall([
function getLogin(callback){
usersModel.findOne({ login: login }, function (err, res) {
console.log('login: ',res.login);
console.log('erreur: ',err);
if (err){
callback(err,null);
return;
}
if(!res)
{
console.log('getLogin - returned empty res');
callback('empty res');
}
if(res != null ){
// test a matching password if the user is found we compare both passwords
var userReceived = res;
callback(null,userReceived);
}
});
},
function getPassword(userReceived, callback){
console.log('login received :',userReceived.login);
var Ulogin = userReceived.login;
var Upassword = userReceived.password;
// function that compare the received password with the encrypted
//one
bcrypt.compare(password, Upassword, function(err, isMatch) {
if (err) {
console.log(err);
callback(err,null);
return;
}
else if (isMatch) {
console.log('Match', isMatch);
callback(null,isMatch);
}
else {
console.log('the password dont match', isMatch);
callback('pwd error',null);
}
});
},
], function(err){
if (err) {
console.error('unexpected error while connecting', err);
return false;
}
console.log('connected successfully');
return true;
});
}
And in my main file server.js i'm doing currently doing :
var connect = users.connection(login,password);
//the goal is to use the connect variable to know if the connection
//failed or not but it's 'undefined'
if(connect){
res.send('youyou connecté');
}
else {
res.send('youyou problem');
}
this absolutely don't work so i tried to use Q library but I have an error saying
"TypeError: Cannot read property 'apply' of undefined at Promise.apply"
here is the code using Q:
app.post('/signup', function (req, res) {
var login = req.body.login;
var password = req.body.password;
Q.fcall(users.connection(login,password))
.then(function (connect) {
if(connect){
res.send('connected');
}
else {
res.send('problem');
}
})
.catch(function (error) {
throw error;
})
.done();
});
but i am a little bit astonished i thought that by using async.waterfall() i told the function to wait until it received all the callbacks return so i don't understand why the connect variable is 'undefined'?

What I don't understand is - what was the flow exactly? did 'usersModel.findOne' get called?
What I see that is missing here in the getLogin function is a callback in the case that both the 'if' statement return false. in this case you'll get stuck in the first function and you won't advance to 'getPassword' function.
If this still doesn't work, please try executing the following code and report what was printed:
exports.connection = function (login,password) {
async.waterfall([
function getLogin(callback){
usersModel.findOne({ login: login }, function (err, res) {
if (err){
console.log('getLogin - error has occured');
callback(err,null);
return;
}
if(!res)
{
console.log('getLogin - returned empty res');
callback('empty res');
}
console.log('getLogin - result seems OK');
// test a matching password if the user is found we compare both passwords
var userReceived = res.items[0].login;
callback(null,userReceived);
}
});
},
function getPassword(userReceived, callback){
console.log('getPassword');
console.log(userReceived);
callback(null,'done')
}
], function(err){
if (err) {
console.error(err);
}
console.log('success');
});
}

Processing a database query in Javascript

I'm using Express and Handlebars to display a value set by the user and stored in the database.
Handlebars is set up to display the value "{{userMotto}}".
Express does the following:
function isUserAuthenticated(req, res, next) {
if (!req.user) {
res.render('index', {
user: req.user
});
} else {
currentUser = req.user.username;
userMottoCaught = queryDatabase("motto", currentUser);
next();
}
}
I want it to set the value of "userMottoCaught" to whatever it finds in the database. The query itself is this:
function queryDatabase(dbCollection, dbUID) {
this.dbCollection = dbCollection;
this.dbUID = dbUID;
return MongoClient.connectAsync(hiddenkeys.mongodbUri)
.then(function(db) {
return db.collection(dbCollection).findOneAsync({
_id: dbUID
});
})
.then(function(item) {
console.log("Found: ");
console.log(item);
return dbQueryResult;
})
.catch(function(err) {
//err
});
}
The problem is that I cannot for the life of me get the dbQueryResult out and return it to function queryDatabase itself. Probably because it's being returned to a sub function right now instead of the main function, I think. I highly suspect this can be easily resolved but I'm just at a loss on how to fix this. I am using Bluebird here to see if I could solve this with promises, but I'm not sure this is the right route either. I've also looked into callbacks but I cannot for the life of me figure out how to apply either concept to my code to solve my problem.
Later on when I render the page I do this to render it on the page:
router.get('/', isUserAuthenticated, function(req, res) {
res.render('dashboard', {
user: req.user,
userMotto: userMottoCaught
});
});
Currently this yields on the page: "Motto: [object Promise]", because I haven't returned the proper value to the main function.
Is there anyone out there with some wise words?
Cheers,
Dean

i think you need to make a callback here
function isUserAuthenticated(req, res, next) {
if (!req.user) {
res.render('index', {
user: req.user
});
} else {
currentUser = req.user.username;
userMottoCaught = queryDatabase("motto", currentUser,function(err,data){
userMottoCaught = data
next();
});
}
}
and the definition of queryDatabase should look like
function queryDatabase(dbCollection, dbUID,cb) {
this.dbCollection = dbCollection;
this.dbUID = dbUID;
return MongoClient.connectAsync(hiddenkeys.mongodbUri)
.then(function(db) {
return db.collection(dbCollection).findOneAsync({
_id: dbUID
});
})
.then(function(item) {
console.log("Found: ");
console.log(item);
dbQueryResult = JSON.stringify(item.motto);
cb(null,dbQueryResult)
})
.catch(function(err) {
//err
cb(err);
});
}

Cannot return values to response with mongoose/mongodb and nodejs

I am using Nodejs, ExpressJs, MongoDB via Mongoose. I have created a simple UserSchema . I have my code separated into multiple files because I foresee them getting complex.
The url '/api/users' is configured to call the list function in 'routes/user.js' which happens as expected. The list function of UserSchema does get called, but it fails to return anything to the calling function and hence no result goes out.
What am I doing wrong ?
I tried to model it based on http://pixelhandler.com/blog/2012/02/09/develop-a-restful-api-using-node-js-with-express-and-mongoose/
I think I am doing something wrong with the function definition of userSchema.statics.list
app.js
users_module = require('./custom_modules/users.js'); // I have separated the actual DB code into another file
mongoose.connect('mongodb:// ******************');
var db = mongoose.connection;
db.on('error', console.error.bind(console, 'connection error:'));
db.once('open', function callback() {
users_module.init_users();
});
app.get('/api/users', user.list);
custom_modules/users.js
function init_users() {
userSchema = mongoose.Schema({
usernamename: String,
hash: String,
});
userSchema.statics.list = function () {
this.find(function (err, users) {
if (!err) {
console.log("Got some data"); // this gets printed
return users; // the result remains the same if I replace this with return "hello"
} else {
return console.log(err);
}
});
}
UserModel = mongoose.model('User', userSchema);
} // end of init_users
exports.init_users = init_users;
routes/user.js
exports.list = function (req, res) {
UserModel.list(function (users) {
// this code never gets executed
console.log("Yay ");
return res.json(users);
});
}

Actually in your code you are passing a callback, which is never handled in function userSchema.statics.list
You can try the following code:
userSchema.statics.list = function (calbck) {
this.find(function (err, users) {
if (!err) {
calbck(null, users); // this is firing the call back and first parameter should be always error object (according to guidelines). Here no error, so pass null (we can't skip)
} else {
return calbck(err, null); //here no result. But error object. (Here second parameter is optional if skipped by default it will be undefined in callback function)
}
});
}
Accordingly, you should change the callback which is passed to this function. i.e.
exports.list = function (req, res){
UserModel.list(function(err, users) {
if(err) {return console.log(err);}
return res.json(users);
});
}