How to use object of one query into nested query in Mongoose

Question

I am new in MongoDb and NodeJs, I am using Mongoose in nodejs, But I am facing a problem, I am using result object of first query into nested query but getting undefined of first query object. please give me any suggestion. Thanks.

LuckyLunch.find(criteria, function (err, lunches) {   // First Query
   if (err) 
       return;
   var allLunches = lunches;   // Accurate result here
   for (var i = 0; i < allLunches.length; i++)
       {
         if (typeof allLunches[i].luckyMatch != 'undefined') {
              var usernames = [];
              Match.findOne(criteria2, function (err, singleMatch) {   // Second Query
                if (singleMatch != null) {
                     var userids = [];
                   for (var k = 0; k < singleMatch.participants.length; k++)
                   {
                      userids.push(ObjectId(singleMatch.participants[k]));
                   }
                      User.find(criteria, function (err, getusers) {  // Third Query
                      for (var j = 0; j < getusers.length; j++)
                          usernames.push(getusers[j].name);

                      allLunches[i].luckyUsers = usernames;  // allLunches[i] is undefined here.

                   });
                 }
              });
            }
          } 
      });

`getting undefined of first query object`, what do you mean? is `lunches` undefined? — Eamonn McEvoy, Oct 20 '16 at 04:58
LuckyLunch.find(criteria, function (err, lunches), here lunches giving the accurate result, but when using inside the nested query (allLunches[i].luckyUsers), here it is undefined. — Umesh Sehta, Oct 20 '16 at 05:00
when ur query object doesn't have key, which ur using that key then it will say undefined — Umakant Mane, Oct 20 '16 at 05:05
@UmakantMane, Key has value, but object is not accessible "allLunches" inside the nested query, Can you give me any alternate to execute the queries in sequence, I think queries are synchronous so the problem is occurring. — Umesh Sehta, Oct 20 '16 at 05:13
similar one, http://stackoverflow.com/questions/10448295/callback-after-for-loop-finishes-in-node-js — Umakant Mane, Oct 20 '16 at 06:11

Umakant Mane · Accepted Answer · 2016-10-20T06:56:09.627

try this,

 var getData = function(callback) {
     LuckyLunch.find(criteria, function (err, lunches) {   // First Query
      if (err) {
         callback(err); 
         return;
      }        
      var len =   lunches.length; // try to use lenches only, Accurate result here
      for (var i = 0; i < len; i++)
       {
        (function(i) { 
         if (typeof lunches[i].luckyMatch != 'undefined') {
          var usernames = [];
          Match.findOne(criteria2, function (err, singleMatch) {   // Second Query
            if (singleMatch) {
                 var userids = [];
               for (var k = 0; k < singleMatch.participants.length; k++)
               {
                  userids.push(ObjectId(singleMatch.participants[k]));
               }
                  User.find(criteria, function (err, getusers) {  // Third Query
                  for (var j = 0; j < getusers.length; j++)
                      usernames.push(getusers[j].name);

                  lunches[i].luckyUsers = usernames;  // allLunches[i] is undefined here.

               });
             }
          });
        }
        })(i);
      }

      callback(null, "put here need data to return"); //this must be end of the ur loop
  });

 }

 getData(function(err, result){

   if(err)
     console.log(err);
     else
     console.log(result); 
 });

Thanks a lot, Its very helpful to me. Its solved my problem. Great ! — Umesh Sehta, Oct 20 '16 at 07:39

score 0 · Answer 2 · answered Oct 20 '16 at 07:39

After some changes , I got my result. My Answer is:

var getData = function (id,callback) {
      var criteria = {
          luckyMatch: { $exists: true },
          companyid: ObjectId(id)

      }
      LuckyLunch.find(criteria, function (err, lunches) {   // First Query
          var len = lunches.length; // try to use lenches only, Accurate result here
          for (var i = 0; i < len; i++) {
              (function (i) {
                  if (typeof lunches[i].luckyMatch != 'undefined') {
                      var usernames = [];
                      var criteria2 = {
                          participants: { $exists: true, $ne: [] },
                          _id: ObjectId(lunches[i].luckyMatch)
                      }
                      Match.findOne(criteria2, function (err, singleMatch) {   // Second Query
                          if (singleMatch) {
                              var userids = [];
                              var len2 = singleMatch.participants.length;
                              for (var k = 0; k < len2; k++) {
                                  userids.push(ObjectId(singleMatch.participants[k]));
                              }
                              var criteria3 = {
                                  _id: { $in: userids }
                              }
                              User.find(criteria3, function (err, getusers) {  // Third Query
                                  var len3 = getusers.length;
                                  for (var n = 0; n < len3; n++) {
                                      lunches[i].luckyUsers.push(getusers[n].name);
                                  }
                                  if (i == len - 1)
                                      callback(null, lunches); //this must be end of the ur loop
                              });
                          }
                      });
                  }
              })(i);
          }
      });
  }

How to use object of one query into nested query in Mongoose

2 Answers2