var user = new mongoose.Schema({

  username : {type: String},
  email    : {type: String,index: {unique: true}},
  password : {type: String},
  feed     : [{
                title       : {type: String},
                description : {type: String},
                latitude    : {type:Number},
                longitude   : {type:Number},
                feedImages  : [{
                                imageUrl: {type: String}
                              }]
             }]
});

app.post('/uploadFeedImage',function(req,res) {
    var _id         = req.body._id;
    var imageUrl    = req.body.imageUrl;
    db.user.update(
        {"feed._id":_id },
        {$push : {
            feedImages:{
                imageUrl:imageUrl
            }
        }
        },function (err,result) {
            if (err) {
                res.json({"success": '0', "message": "Error adding data"});
            }
            else {
                res.json({"success": '1', "message": "Data added"});
            }
        });
});

db.user.update(
        {"feed._id":_id },
        {$push : {
            "feed.$.feedImages":{
                imageUrl:imageUrl
            }
        }
        },function (err,result) {
            if (err) {
                res.json({"success": '0', "message": "Error adding data"});
            }
            else {
                res.json({"success": '1', "message": "Data added"});
            }
        });