node.js - Mongoose embedded document update not persisting -

i'm working mean stack , i'm trying update embedded document. appears work on execution, data not persist after refresh:

    // update answer exports.updateanswer = function(req, res) {   var ansid = req.params.aid;   var result;   poll.findbyid(req.params.id,function(err, poll){     if(err) { return handleerror(res, err); }     poll.answers.foreach(function(answer){       if(ansid == answer._id) result = answer;     })     var updated = _.merge(result, req.body);     poll.markmodified('answers');     updated.save(function (err) {       if (err) { return handleerror(res, err); }       return res.json(200, poll);     });   }); }; 

my schema:

'use strict';  var mongoose = require('mongoose'),     schema = mongoose.schema,     objectid = schema.objectid;  var answerschema = new schema({   answer: string,    votes:{type: number, default: 0} });  module.exports = mongoose.model('answer', answerschema);  var pollschema = new schema({   author: string,   question: string,   answers: [answerschema] });  module.exports = mongoose.model('poll', pollschema); 

put request:

 $scope.vote = function(answer) {       $scope.pollobj.answers.foreach(function(el,indx){         if(el['_id'] == $scope.radioval.selected) {           el['votes']++;           $http.put('/api/polls/'+$scope.pollid+'/answers/'+el['_id'],el).           success(function(data){             console.log(data);           })         }       }) 

answer provided laggingreflex:

exports.updateanswer = function(req, res) {       var ansid = req.params.aid;       var result;       poll.findbyid(req.params.id,function(err, poll){         if(err) { return handleerror(res, err); }         poll.answers.foreach(function(answer){           if(ansid == answer._id) result = answer;         })         var updated = _.merge(result, req.body);         poll.markmodified('answers');         poll.save(function (err) { // <== change here           if (err) { return handleerror(res, err); }           return res.json(200, poll);         });       });     };