express - Node.js - waiting on all Model.find() to finish -

i have following 2 monogoose models:

clanmember: tag:string, name:string; war: members:array; #array of tags 

i finding array of current members by:

clanmember.find({     'tag': {         $in: membertags #an array of tags     } }).limit(membertags.length)   .exec(function(err, members) {  } 

from want execute war.find()s , add info each member document, this:

clanmember.find({     'tag': {         $in: membertags     } }).limit(membertags.length)     .exec(function(err, members) {      var memberarray = [];      (var member in members) {         if (members.hasownproperty(member)) {             var currentmember = members[member];             war.find({members: currentmember.tag}).exec(function(err, wars) {                 currentmember.wars = wars;                 memberarray.push(currentmember);             });         }     }     #i want render here  }); 

after happens, i'd pass whole new array of member objects (with war objects) view:

    res.render('members', {         members: memberarray,     }); 

what best way of ensuring war.find() functions found , finished executing before passing array render function?

for have use promises. code should below.

var promise = require('promise'); clanmember.find({     'tag': {         $in: membertags     } }).limit(membertags.length)     .exec(function(err, members) {     var promises = [];     var memberarray = [];      members.foreach((member)=>{             var currentmember = member;             let warpromise = war.find({members: currentmember.tag}).exec().then(function(wars) {                 currentmember.wars = wars;                 memberarray.push(currentmember);                 return true;             }).catch(function(err){                throw err;             });             promises.push(warpromise);         }     });       promise.all(promises).then(function(result){       #i want render here        }).catch(function(err){        });  }); 

here promise.all() function ensure previous promises has been completed. , can give response then.