CODEWITHSUNDEEP
javascriptnode.jsmongodbexpress
Areg
Areg

Reputation: 1485

Express does not return valid response

i am trying to use mongodb to get some data for our analytics page, there's alot of data that's processing but for some reason the express returns empty array as response even when i use console log i see the data on terminal.

This is my endpoint

import Analytics from '../classes/Analytics';
import { Router } from 'express';
import role from '../middleware/role';

const router = Router();

router.use(role('admin'));


router.get('/analytics/weekly', async (req, res) => {
    try {
        const data = await Analytics.getWeekly();

        return res.status(200).send({ data });
    } catch (err) {
        console.log(err);
        return res.status(500).send({ message: 'Something went wrong, please try again later!' });
    }
});

module.exports = router;

This is where all the magic happens for data variable

class Analytics {
    static async getWeekly() {
        // ignore this one day difference thing
        const startDate = moment().subtract(1, 'days').startOf('week').format();
        const endDate = moment().subtract(1, 'days').endOf('week').format();

        try {
            const orders = await Order.find(
                {
                    sent_at: {
                        $gte: startDate,
                        $lte: endDate,
                    },
                },
                { user: 1, created_at: 1, sent_at: 1 }
            );

            let counter = [];

            for await (const item of orders) {
                const date = moment(item.sent_at).format('YYYY-MM-DD HH');

                if (!counter[date]) counter[date] = [];

                if (!counter[date][item.user.username]) counter[date][item.user.username] = 0;

                counter[date][item.user.username] += 1;
            }

            return counter;
        } catch (err) {
            console.log(err);
        }
    }
}

The point of the static method above is to fetch all orders and count how many times which user has handled the order.

Now when i console.log the data from the router endpoint i see the data on console perfectly just how i wanted it to be

 '2021-07-03 22': [
    Johnson: 10,
    Mikaels: 15,
    Vasquez: 24,
    Blaskovich: 3
  ],
  '2021-07-03 23': [
    Johnson: 2,
    Vasquez: 12,
    Mikaels: 15,
    Blaskovich: 5
  ]

The problem is when i make a request to my endpoint it returns an empty array []. What am i missing here?

Upvotes: 0

Views: 49

Answers (1)

jfriend00
jfriend00

Reputation: 707188

Change this:

if (!counter[date]) counter[date] = [];

to this:

if (!counter[date]) counter[date] = {};

And this:

let counter = [];

to this:

let counter = {};

Your code here:

if (!counter[date][item.user.username]) counter[date][item.user.username] = 0;

Is adding a property to an array, not adding an array element. And JSON.stringify() ignores properties on an array. It only serializes actual array elements so when you try to send the JSON version of the array, it always appears empty.

So, when you call res.status(200).send({ data });, the .send() method serializes your object which contains a bunch of arrays that have no actual array elements, only properties.

By changing the arrays to be objects, then JSON.stringify() will serialize all those properties. Arrays and Objects have many things in common, but they are not the same. You should use the appropriate type for your situation.

In addition, change this:

    } catch (err) {
        console.log(err);
    }

to this:

    } catch (err) {
        console.log(err);
        throw err;
    }

So that you are properly propagating errors back to the caller. Otherwise, you're just eating the error and returning undefined, both of which will cause problems for the caller.

Upvotes: 2

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