Wsrtjtyk

I have this request handler on my node server. It has three MongoDB queries, and I want all the results to be returned, before the response is sent.

api.get('/getStats/:productID', (req,res)=>{

  let data = {};

  let dailySales = ;

  let avgProduct = "";

  let customers = ;



  Sales.find({productID: productID}).then(

    sales => {

      dailySales = sales;

    }

  );



  Products.find({}).then(

    products => {

      // Calculate Avg product here

      avgProduct = result;

    }

  );



  Customers.find({}).then(

    customers => {

      customers = customers;

    }

  );



  data = {

    dailySales,

    avgProduct,

    customers

  };



  res.json(data);

});

But running this returns

data: {

  dailySales: ,

  avgProduct: "",

  customers: 

}

i.e. The Mongo response is returning before the data is run. Please how to I fix. Thank You

you can try using the Promise.all where you can pass the MongoDB queries as parameter to it ,the promise will be resolved when all the queries return the result in the array

wait for all the promises to resolve before sending the actual response

const sales = Sales.find({productID: productID});

const allProducts = Products.find({});

const allCustomers = Customers.find({});



Promise.all([sales, allProducts, allCustomers])

 .then(data => res.json(data));  

Try using the in-built util.promisify function along with
async-await to get data correctly!

const promisify = require('utils').promisify;



const salesFindOnePromise = promisify(Sales.find);

const productsFindAllPromise = promisify(Products.find);

const customersFindAllPromise = promisify(Customers.find);



findDailySalesByIdAsync = async (productID) => {



    try {

        return await salesFindOnePromise({ productID: productID });

    } catch(err) {

        throw new Error('Could not fetch the appropriate sales with productID');

    }



}



findProductsAsync = async () => {



    try {

        return await productsFindAllPromise({});

    } catch (err) {

        throw new Error('Could not fetch sales!');

    }

}



findCustomersAsync = async () => {



    try {

        return await customersFindAllPromise({});

    } catch (err) {

        throw new Error('Could not fetch customers!');

    }

}





api.get('/getStats/:productID', async (req,res)=>{



try {

  const dailySales = await findDailySalesByIdAsync(productID);

  const avgProduct = await findProductsAsync();

  const customers = await findCustomersAsync();



    const data = {

        dailySales,

        avgProduct,

        customers

    };



    return res.status(200).send(data);



  } catch(err) {

    console.err(`Failed because: {err}`);

    throw new Error('Could not fetch data because of some error!');

  }



});