查找不起作用mongodb

Question

my views data :

{
"msg": "Recently Viewed Experiences",
"data": [
    {
        "_id": "5aafce9ea33f68234466b790",
        "userId": "5aaf58dccf409c770353b5d1",
        "expId": "5aabc6d7bdd1940858284b09",
        "__v": 0,
        "created": "2018-03-19T14:52:14.154Z"
    },
    {
        "_id": "5ab09cec046e802b9c0599fc",
        "userId": "5aaf58dccf409c770353b5d1",
        "expId": "5aafdc7abea7fe08c778885d",
        "__v": 0,
        "created": "2018-03-20T05:32:28.436Z"
    }
  ]
}

my find functon :

 function getViewedExperiences(){
    return new Promise(function(resolve,reject){
        Views.find(
            [{userId: req.userId},{$lookup: {from: "experiences",localField: "_id",foreignField: "expId",as: "experience"}}
            ],function(err,result){
            if(err){
                reject(err);
            }else{
                resolve(result);
            }
        });
    });
 }

my experience :

 {
        "_id": "5aabc6d7bdd1940858284b09",
        "name": "My First Experience",
        "subtitle": "Experience Subtitle ",
        "description": "Welcome to a soulful experience of vacationing in India, the cradle of ancient civilization with rich cultural heritage.",
        "whatwedo": "Experience the sights and sounds of its amazing diversity that is embedded in its geography, people and their cultures. Explore the gifts of nature and the timeless marks",
        "whocancome": "Any on can come\n",
        "whatweprovide": "Experience the sights and sounds of its amazing diversity that is embedded in its geography",
        "cancellationPolicy": "Cancellation Policy. We require 14 days cancellation notice prior to your scheduled arrival, otherwise we will charge you cancellation fee as below. 10% of your total amount will be charged if you do not notify us about your cancellation or any changes by 14 to 8 days before your scheduled arrival",
        "hostPhone": "400",
        "geoLocation": [
            28.628454,
            28.628454
        ],
        "price": 4000,
        "__v": 0,
        "dateCreated": "2018-03-20T05:32:42.876Z",
        "rating": 5,
        "currency": "Pound",
        "address": "G70, Sector 63 Noida",
        "status": "live",
        "images": [
            "[\"https://thumbnails.trvl-media.com/59v7eyda1z0_UsX4oB0MuP8b8Ao=/a.travel-assets.com/flex/flexmanager/images/2018/02/27/TVLY_PromoCode_TRIPTIME_lpad_532x299_20180131.jpg\"]"
        ]
    }

I need to lookup data from other experiences documents in my views document there is a foreign field expId which is _id in my experiences document i want to fetch data from experiences. i used $lookup but its not working for me

Answer 1

function getViewedExperiences(){
    return new Promise(function(resolve,reject){
        Views.find(
            {userId: req.userId}
        ).populate({
            path:'expId',
            model:Experiences
        }).exec(function(err,result){
            if(err){
                reject(err);
            }else{
                resolve(result);
            }
        });
    });
}