CODEWITHSUNDEEP
javascriptnode.js
JerinJoseph
JerinJoseph

Reputation: 18

Wait until forEach fetch data from db

I am trying to implement a forEach to fetch data from a mongo database and push each data to an array. I need to console log that array after all data is pushed. I tried with a promises but couldn't get desired result. Here's what I've got

count=[];
array.forEach((data)=>{
    userDetailsModel.find({UpdateStatusDate:data}).countDocuments()
    .exec((err,data)=>{count.push(data)}) 
})

Thanks for any help!

Upvotes: 0

Views: 545

Answers (3)

Ilijanovic
Ilijanovic

Reputation: 14904

Make sure your function has async keyword infront of it and you should be good to go

let count = await Promise.all(
  array.map(data =>
    userDetailsModel
      .find({ UpdateStatusDate: data })
      .countDocuments()
      .exec()
  )
);
consle.log(count);

Upvotes: 1

Piou
Piou

Reputation: 1066

You are missing the point of the promise pattern applied to an array of promises.

Exec will return a promise that will resolve only for one element of the data array. Thus you will have a promise for each data in your array and your code must wait for all promises to resolve. Keep in mind this will result in one Mongo query per data in your array.

Best way to do so is to map your data array to an array of promises and use Promise.all to wait for all of them to resolve:

// get an array of promises for each data to query:
let promises = array.map(data => { 
    return userDetailsModel
        .find({UpdateStatusDate:data})
        .countDocuments()
        .exec(); 

});
    
// when all the promises fulfill 
Promise.all(promises).then(counts => {
    console.log(counts);
    // for each counts log the result:
    counts.forEach(result => { console.log(result); });
});

Upvotes: 1

Dj0ulo
Dj0ulo

Reputation: 470

You could use the Promise.all() method to wait after all promises

let count = [];
const promiseArray = array.map((data) => (
  new Promise((resolve) => {
    userDetailsModel.find({ UpdateStatusDate: data })
      .countDocuments()
      .exec((err, data) => { resolve(data) })
  })
))
Promise.all(promiseArray).then((values) => {
  count = values;
  console.log(count);
});

Upvotes: 0

Related Questions