AsyncNodeJS: Error: Callback was already called

Question

I am new to node.js and I have to solve a bug in it. I am trying to update the group members by the following service and whenever I try to call this API, I got error as

Error: Callback was already called.

My code is:

'app.post('/api/updateGroup/:group_id', function (req, res) {
  var checkGroup = Group.findOne({'_id': req.params.group_id}).exec();
    checkGroup.addBack(function( err , existingGroup ) {
        if ( err ) {
            res.json({'message' : err });
        }else if( existingGroup ){

Group.findOne({ '_id': req.params.group_id })
        .execQ()
        .then(function(existingUser) {
            var friendphoneNumber = req.body.friendphoneNumber.split(',');

            var friends = [];
            console.log('existingUser', friendphoneNumber);

            async.each(friendphoneNumber, function(phonenum, callback) {

                var phonenum = phonenum.split("\'")[0];
                console.log('phonenum', phonenum);

                User.findOne({
                    'phoneNumber': phonenum
                })
                .execQ()
                .then(function(existingFriend) {

                    if(existingFriend === null) {
                        friends.push({
                            'details': {
                                'phoneNumber': phonenum
                            }
                        });
                        callback();

                    } else {

                        friends.push({'details': existingFriend});
                        callback();
                    }

                })
                .catch(function(err) {
                    console.log('err', err)
                    friends.push({
                        'details': {
                            'phoneNumber': phonenum
                        }
                    });
                    callback();
                 })
                .done(function() {

                });

            }, function(err) {
                console.log('callback')

                group.group_id = req.params.group_id;
                // group.user_id = req.body.userId;
                // group.createdDate = moment().format('YYYY-MM-DD hh:mm a');

                group.friends = friends;

                group.update(function(err) {
                    if (err) {
                        res.json({
                            message: err
                        });
                    } else {

                        res.json({
                            success: 1,
                            message: 'Group updated',
                            group: group
                        });
                    }
                });


            });

        })
        .catch(function(err) {
            res.json({
                success: 0,
                message: 'user id Not Match. Please try again'
            });

        })
        .done(function(events) {


        });
    }
    else {

        console.log('nope');
    }

});


});

I have seen few answers regarding the same, but still I can't solve it.

Answer 1

If callback throws an error, it is going to get called in both the then and the following catch. You should probably be calling it in the done function.

            .then(function(existingFriend) {

                if(existingFriend === null) {
                    friends.push({
                        'details': {
                            'phoneNumber': phonenum
                        }
                    });
                } else {

                    friends.push({'details': existingFriend});
                }

            })
            .catch(function(err) {
                console.log('err', err)
                friends.push({
                    'details': {
                        'phoneNumber': phonenum
                    }
                });
             })
            .done(function() {
                callback();
            });