How to multiple fetch data expressJS

Question

I want to display chatbot and facebook data at the same time. how to display it? because when I try to run in the browser but it does not appear anything. I've tried to look it up on stackoverflow but did not get the right reference

route.js

app.get('/cpanel/facebook', function(req, res) {
        if (req.session.user == null) {
            res.redirect('/cpanel/login');
        }   else {
            CB.getAllRecords( function(e, chatbot) {
                res.render('cpanel/facebook', { udata : req.session.user, chatbot : chatbot });
            });
            FBM.getAllRecords( function(e, facebook) {
                res.render('cpanel/facebook', { udata : req.session.user, facebook : facebook });
            });
        }
    });

facebook.js

var facebook = db.collection('facebook');

exports.addNewFacebook = function(newData, callback) {
    facebook.findOne({accesstoken:newData.accesstoken}, function(e, o) {
        if (o) {
            callback('accesstoken-taken');
        }   else {
            facebook.insert(newData, {safe: true}, callback);
        }
    });
}

exports.getAllRecords = function(callback) {
    facebook.find().toArray(
        function(e, res) {
            if (e) callback(e)
            else callback(null, res)
        }
    );
}

chatbot.js

var chatbot = db.collection('chatbot');

exports.addNewChatBot = function(newData, callback) {
    chatbot.insert(newData, {safe: true}, callback);
}

exports.getAllRecords = function(callback) {
    chatbot.find().toArray(
        function(e, res) {
            if (e) callback(e)
            else callback(null, res)
        }
    );
}

Short answer. Use the promises interface instead of the plain callback insterface with your database and then use Promise.all() to track when both requests are done. You will want to switch to promises for managing asynchronous operations because it's way simpler to manage multiple async operations when using promises. — jfriend00
– jfriend00, Commented Dec 17, 2017 at 4:38

jfriend00 · Accepted Answer · 2017-12-17 09:46:46Z

2

The easier way to manage asynchronous operations in node.js, especially when you have more than one operation that you want to coordinate is to use Promises instead of plain callbacks. And, fortunately, mongodb supports a promise-based interface for all its asynchronous operations now.

So, first change your methods to return a promise instead of taking a callback:

var chatbot = db.collection('chatbot');

exports.getAllRecords = function() {
    return chatbot.find().toArray();
}

var facebook = db.collection('facebook');

exports.getAllRecords = function() {
    return facebook.find().toArray();
}

Then, you can use those promises with Promise.all() to coordinate:

app.get('/cpanel/facebook', function(req, res) {
    if (req.session.user == null) {
        res.redirect('/cpanel/login');
    } else {
        Promise.all([CB.getAllRecords(), FBM.getAllRecords()]).then(results => {
            res.render('cpanel/facebook', { udata : req.session.user, chatbot : results[0], facebook: results[1]});
        }).catch(err => {
            // render some error page here
            res.sendStatus(500);
        });
    }
});

For a call to just a single function that returns a promise, you can use .then():

app.get('/cpanel/facebook', function(req, res) {
    if (req.session.user == null) {
        res.redirect('/cpanel/login');
    } else {
        FBM.getAllRecords().then(results => {
            res.render('cpanel/facebook', { udata : req.session.user, facebook: results});
        }).catch(err => {
            // render some error page here
            res.sendStatus(500);
        });
    }
});

edited Dec 17, 2017 at 9:46

answered Dec 17, 2017 at 5:13

jfriend00

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9 Comments

Doctor Robot Over a year ago

Thank you for the help. I tried to follow the code you gave, but the error appears: SyntaxError: Unexpected token>

jfriend00 Over a year ago

@ArifFirmansyah - On what line of code is that error? Are you sure you copied the code here exactly? What version of node.js are you running?

Doctor Robot Over a year ago

sorry I wrong copy paste. now can run in browser. i want to ask too, does promise.all it need npm install --save promise-all? because I do that

jfriend00 Over a year ago

@ArifFirmansyah - Promise.all() is part of ES6 and is built into recent versions of node.js so it does not need to be separately installed.

Doctor Robot Over a year ago

I want to ask again, how to display single data? for example just chatbot only

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