NodeJs: aSync forEach inside mongoose find

Question

I guess it should be simple for those who familiar with Node.js and Mongoose. I'm trying to get the final result inside async forEach and mongoose find, I can see the results fine in the middle of the function, but when Im trying to get it after the second forEach, I cant.

I have tried to catch the last iteration and bring the results back, but because its async, the last iteration arrived before the find in the middle of the function.

Any suggestions? Here is what I have:

function addUsersInfoForEachVote(req, res, next){
    var itemsProcessed = 0;
    Questions.findOne({_id: req.body.question}, {answers: 1}).exec(function (err, question) {
        var finalVotes = [];
        if (err | !question) {
            return res.send({
                errors: err | "No Question Found"
            });
        } else {
            question.answers.forEach((answer, index, array) => {
                var votedUsers = [];
                votedUsers = votedUsers.concat(answer.get("votes"));
                answer._doc.votes = answer.get("votes").length;
                var ansId = answer.answerId;
                var aData = {answer: answer, users: {}};
                AnswersVote.find({'_id': {$in: getUniqueIds(votedUsers)}},{user: 1})
                           .populate('user', 'name gender')
                           .exec(function(err, votesUsers){
                                if (!err) {
                                    votesUsers.forEach(function(vote){
                                        var user = vote.get("user");
                                        if (user){
                                            aData.users[user.get("id")] = user;
                                        }
                                    });
                                    console.log("ADATA:"+JSON.stringify(aData)); //Here I can see it well! (the second time contain it all)
                                }
                            });
                //currAns = votedUsers;
                itemsProcessed++;
                if( itemsProcessed === array.length) {
                //HERE I NEED THE FINAL RESULTS:
                    console.log("ADATA after:"+JSON.stringify(aData));
                    next();
                }
            });    
        }

    });
}

Second, change if (err | !question) to just if (err) (if you want to use that anyway, the correct syntax is if (err || !question) — Derek Pollard
– Derek Pollard, Commented Aug 17, 2016 at 8:56

Abhilash Km · Accepted Answer · 2016-08-17 10:11:05Z

You can use async eachLimit or each here Read doc(http://caolan.github.io/async/docs.html#.eachLimit)

async.eachLimit((question.answers || []), 4, function(answer, callback) {
        var votedUsers = [];
        votedUsers = votedUsers.concat(answer.get("votes"));
        answer._doc.votes = answer.get("votes").length;
        var ansId = answer.answerId;
        var aData = {
            answer: answer,
            users: {}
        };
        AnswersVote.find({
            '_id': {
                $in: getUniqueIds(votedUsers)
            }
        }, {
            user: 1
        })
            .populate('user', 'name gender')
            .exec(function(err, votesUsers) {
                if (!err) {
                    votesUsers.forEach(function(vote) {
                        var user = vote.get("user");
                        if (user) {
                            aData.users[user.get("id")] = user;
                        }
                    });
                    console.log("ADATA:" + JSON.stringify(aData));
                }
                callback(err);
            });

    },
    function(error) {
        next();
    }
});

Shrabanee · Accepted Answer · 2016-08-17 08:57:51Z

0

May be you can use async.waterfall to achieve the desired result.

Refer doc for more information.

Try something like below code:-

function addUsersInfoForEachVote(req, res, next){
var itemsProcessed = 0;
  Questions.findOne({_id: req.body.question}, {answers: 1}).exec(function (err, question) {
    var finalVotes = [];
      if (err | !question) {
          return res.send({
              errors: err | "No Question Found"
          });
     } else {
question.answers.forEach((answer, index, array) => {
  var votedUsers = [];
    votedUsers = votedUsers.concat(answer.get("votes"));
    answer._doc.votes = answer.get("votes").length;
var ansId = answer.answerId;
var aData = {answer: answer, users: {}};

async.waterfall([
     function(callback){
       AnswersVote.find({'_id': {$in: getUniqueIds(votedUsers)}},{user: 1}).populate('user', 'name gender').exec(function(err, votesUsers){
        if (!err) {
            votesUsers.forEach(function(vote){
                var user = vote.get("user");
                if(user){
                aData.users[user.get("id")] = user;
              }
            });
          console.log("ADATA:"+JSON.stringify(aData)); //Here I can see it well! (the second time contain it all)

          callback(null);
        }
      });
    },
    function(callback){
         //currAns = votedUsers;
    itemsProcessed++;
    if(itemsProcessed === array.length) {
       //HERE I NEED THE FINAL RESULTS:
         console.log("ADATA after:"+JSON.stringify(aData));
          callback(null);
        }
     else {callback(null);}
    }
], function(err){next();})
});

This may help you. Let me know if it works.

answered Aug 17, 2016 at 8:57

Shrabanee

2,7861 gold badge21 silver badges32 bronze badges

4 Comments

Eran Levi Over a year ago

Thank you!, I just copied, and I have "async is not defined", Ill try to debug it anyway..

chridam Over a year ago

You need to require the module first: var async = require('async'); and make sure you do npm install async --save

Eran Levi Over a year ago

Thanks @chridam Ill try it (although, I think we went too far with it, I think its something with my design)...

Shrabanee Over a year ago

Make sure you went through the doc before using the code, so that it will be clearer for you.

Eran Levi · Accepted Answer · 2016-08-18 23:14:02Z

First, Thank you all for your help, I'm personally trying to avoid using external libraries if its unnecessary, and because I can check the amount of answers before, here is the right answer:

function addUsersInfoForEachVote(req, res, next){
      Questions.findOne({_id: req.body.question}, {answers: 1}).exec(function (err, question) {
        var finalVotes = [];
          if (err || !question) {
              return res.send({
                  errors: err || "No Question Found"
              });
          } else {
        var ansNum=0; //FOR MY ITERATIONS
        var fAns = {full : {}}; //FOR MY FINAL ANSWER

        //Here, I can assume we have only two answers so:
    question.answers.forEach(function (answer) {
      var votedUsers = [];
        votedUsers = votedUsers.concat(answer.get("votes"));
        answer._doc.votes = answer.get("votes").length;
        //answer._doc.answer = votedUsers;
      var ansId = answer.answerId;
      var aData = {answer: answer, users: {}};

  AnswersVote.find({'_id': {$in: getUniqueIds(votedUsers)}},{user: 1}).populate('user', 'name gender').exec(function(err, votesUsers){
            if (!err) {
                votesUsers.forEach(function(vote){
                    var user = vote.get("user");
                    if(user){
                    aData.users[user.get("id")] = user;
                  }
                });
            }
fAns.full[ansId] = aData;
if(ansNum > 0){ //The number of the answers here is "2", but this value can be changed
  console.log("FINAL:"+JSON.stringify(fAns)); //Here I have the full response now :)
  res.jsonp(fAns);
}
            ansNum++;
        });
    });

          }

        });

      }

Thanks again anyway.

Collectives™ on Stack Overflow

NodeJs: aSync forEach inside mongoose find

3 Answers 3

Comments

4 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

4 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related