How can get two collection documents and calculate points using express.js?

Question

exports.show = = function(req, res) {
    var userdata = [{
        "productcode": "9563456789",
        "cost": "1000"

    }, {
        "productcode": "8756348947",
        "cost": "5600"

    }]



    var parameterObject = [];

    Parameter.find().exec(function(err, Parameters) {
        if (err) {
            return handleError(res, err);
        }
        // i want to push Parameters[0].value to parameterObject
        parameterObject.push({
            pointvalue: Parameters[0].value
        });


    });


    for (var i = 0; i < userdata.length; i++) {

        Product.find({
            'productcode': userdata[i].productcode
        }).exec(function(err, Products) {
            if (err) {
                return handleError(res, err);
            }
            var point = 0;
            if (!Products) {
                point = 0;
            } else if (Products[0].product.point > 0) {
                point = Products[0].product.point;
            }
            if (point > 0) {

                // here i am not getting userdata[i].cost
                //parameterObject.pointvalue value also not getting
                totalprice = userdata[i].cost / parameterObject.pointvalue * point;
            }


        });
    }
};

Here i have written function for calculating totalprice. i have mentioned userdata(this is my req.body).

Expectation :

i need to store Parameters objects in some variable to access where ever i want. i want to pass userdata object in Product.find() function

how can i calculate this

totalprice= userdata[i].cost/parameterObject.pointvalue) * point);

if you expect someone to read your code, understand your problem and come up with a solution, please take the time to at least format it! It's like 3 keystrokes in any IDE/editor — Balázs Édes, Nov 22 '16 at 09:31
Possible duplicate of [How do I return the response from an asynchronous call?](http://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call) — DrakaSAN, Nov 22 '16 at 09:49
@mojo: Yes I could, but if you took the time to read the duplicate, or anything about asynchronous programming, you should have understood where is your error. Your attitude of "plz giv me ze codzzz" doesn't help at all. — DrakaSAN, Nov 22 '16 at 10:08
@DrakaSAN i did not understand that and i dont think both are same — its me, Nov 22 '16 at 10:14
They are, you just use Promises instead of callback, and a part of the accepted answer scecifically adress their use — DrakaSAN, Nov 22 '16 at 10:19
I did, and even reformatted it. The error is simple and nagging me will not help — DrakaSAN, Nov 22 '16 at 10:28
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/128699/discussion-between-mojo-and-drakasan). — its me, Nov 22 '16 at 10:29
@mojo you can you node js promises for that. you better search some ducumentation with that — Beginner, Nov 22 '16 at 11:36

score 1 · Answer 1 · answered Nov 22 '16 at 09:27

You can use promises when you want to use the result of two functions and later use it for further computation.

In your case, you can execute the two asynchronous functions in parallel. It can look like this.

Promise.all([
    asyncFunc1(),
    asyncFunc2(),
])
.then(function(result){
    // result is an array and has the response of the functions which is
    // result[0] and result[1]
    ···
   // you can manipulate the result of the functions here
})
.catch(function(err){
    // Receives rejection/error among the Promises
    ···
});

Here asyncFunc1() will be your first find function

asyncFunc2() will be your second find function.

The result[0] and result[1] will be the results of the functions respectively.

Later you can use the result to do further computations.

Hope this helps.

http://stackoverflow.com/questions/41124705/based-on-value-how-to-create-new-document-using-node-js-mongodb — its me, Dec 14 '16 at 07:07

Beginner · Accepted Answer · 2016-11-23T07:12:04.737

1

exports.show = = function(req, res) {
    var userdata = [{
        "productcode": "9563456789",
        "cost": "1000"

    }, {
        "productcode": "8756348947",
        "cost": "5600"

    }]

    var parameterObject = [];

    Parameter.find().exec(function(err, Parameters) {
        if (err) {
            return handleError(res, err);
        }
        // i want to push Parameters[0].value to parameterObject 
        parameterObject.push({
            pointvalue: Parameters[0].value
        });

        return FindProducts(parameterObject, function(data) {
            console.log(data);
        });
    });

    function FindProducts(parameterObject, callback) {
        for (var i = 0; i < userdata.length; i++) {
            var totalprice = 0;
            findProduct(i, parameterObject,  function(i, price) {
                totalprice += price;
                if (i <= userdata.length) {
                    return callback({
                        "userid": "myuserid",
                        "total": totalprice
                    });
                }
            });
        }
    }

    function findProduct(i, parameterObject, callback) {
        Product.find({
            'productcode': userdata[i].productcode
        }).exec(function(err, Products) {
            if (err) {
                return handleError(res, err);
            }
            var point = 0;
            if (!Products) {
                point = 0;
            } else if (Products[0].product.point > 0) {
                point = Products[0].product.point;
            }
            if (point > 0) {

                // here you can now get the value of userdata[i].cost 
                // here you can now get the value of parameterObject 
                totalprice = userdata[i].cost / parameterObject[0].pointvalue * point;

                return callback(i, totalprice);
            }

        });
    }


};

edited Nov 23 '16 at 07:12

answered Nov 22 '16 at 11:43

Beginner

4,118
3
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26

not running this function Product.find() and i add console.log(userdata[i].productcode) .its continusly printing only 9563456789 value in console – its me Nov 22 '16 at 12:31
Where did you put the console? – Beginner Nov 22 '16 at 12:32
inside while loop – its me Nov 22 '16 at 12:36
while (i < userdata.length) { //console.log(userdata[i].productcode); – its me Nov 22 '16 at 12:37
Did you try to put it inside find() callback – Beginner Nov 22 '16 at 13:22
Where i need to add callback sir@NewbeeDev – its me Nov 23 '16 at 03:12
@mojo let us continue in chat – Beginner Nov 23 '16 at 03:15
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/128773/discussion-between-mojo-and-newbee-dev). – its me Nov 23 '16 at 05:12
@mojo the chat has gone – Beginner Nov 23 '16 at 06:58
http://stackoverflow.com/questions/43501008/how-to-do-find-in-node-and-mongodb.help – its me Apr 19 '17 at 16:24

How can get two collection documents and calculate points using express.js?

2 Answers2

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