How to store the return value of a mongoose collection into JavaScript array?

Question

In my JavaScript program, I would like to get the "Booking" collection fetched from MongoDB and then store the return value into a JavaScript variable.

router.get('/dashboard', function(req, res){
    //hardcode some value for testing, the program can pass this value.
    var booking = [{id: 1, name:"AAA"}, {id: 2, name:"BBB"}, {id: 3, name:"CCC"}];

    Booking.collection.find().toArray(function(err, docs) {
        console.log(docs);
        console.log("S-------------------------------------------------");
        // assign the returned value from collection to "booking" variable
        booking = docs; // Booking variable can store the value.
        console.log(booking); //can print the value here
        console.log("E-------------------------------------------------");
    });   

    // After execution of above statement, "booking" variable does not contain any value 
    // (because I cannot get the value after running the last code.)
    // Why?? How can I resolve it?

    // The "booking" variable does not contain value after execution of below code.
    res.render('dashboard', {booking:booking});
});

I can successfully get the return value but I have no idea how to store this value in my local JavaScript variable for further action.

Do anyone advise how to resolve this issue? Thank you.

Andres Jimenez · Accepted Answer · 2018-04-01 03:30:48Z

1

Ok, the problem here is that the Mongoose action is asynchronous. So you should manage the booking data inside the callback

`

Booking.collection.find().toArray(function(err, docs) {
    if(!err){
       res.render('dashboard', {booking:docs});
   }
});

`

I also recommend you as a good practice to manage all the database interaction (fetch, add ,delete ...) in a separate module. It could be a helper folder.

Helpers are 'general' helper objects (not feature specific) that execute 'static' functions that are useful throughout the entire application. For example, a function that manages string or date parameters, a function that parses the response of an ajax call, a function that manages proper cleanup of view objects, etc... https://www.quora.com/What-is-the-best-folder-structure-practice-for-Javascript-Backbone-related-to-delegate-helper-functions

And then manage their response with a callback function or promises.

answered Apr 1, 2018 at 3:30

Andres Jimenez

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2 Comments

Newbiee Over a year ago

Thanks, I solved the problems using your suggestion.

Andres Jimenez Over a year ago

You are welcome. If you need anything else don't doubt to ask it.

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