Populating in array of object ids

Question

My schema:-

var playlistSchema = new Schema({
name        : {type:String,require:true},
videos      : {type:[mongoose.Schema.Types.ObjectId],ref: 'Video'},
},{collection:'playlist'})

var Playlist = mongoose.model('Playlist',playlistSchema);

I have some data in the database as exapmple:-

{
"_id" : ObjectId("58d373ce66fe2d0898e724fc"),
"name" : "playlist1",
"videos" : [ 
    ObjectId("58d2189762a1b8117401e3e2"), 
    ObjectId("58d217e491089a1164a2441f"), 
    ObjectId("58d2191062a1b8117401e3e4"), 
    ObjectId("58d217e491089a1164a24421")
],
"__v" : 0

}

And the schema of Video is :-

var videoSchema = new Schema({
name        : {type:String,required:true},
createdAt   : {type:String,default:new Date()},
isDisabled  : {type:Boolean,default:false},
album       : {type: mongoose.Schema.Types.ObjectId, ref: 'Album'}
},{collection:'video'})

var Video = mongoose.model('Video',videoSchema);

Now in order to get the name of the all the videos in playlist i am trying the code:-

 var playlistModel = mongoose.model('Playlist');
let searchParam = {};
searchParam._id = req.params.pid;
playlistModel.findOne(searchParam)
.populate('[videos]')
.exec(function(err,found){
    if(err)
        throw err;
    else{
        console.log(found.videos[0].name);
    }
})

But here i am getting the undefined result.I am not getting where i am wrong plzz anyone help me to short out this problem.

Answer 1

got the answer:- just change the schema

var playlistSchema = new Schema({
name        : {type:String,require:true},
videos      : [{type:mongoose.Schema.Types.ObjectId,ref: 'Video'}],
},{collection:'playlist'})

var Playlist = mongoose.model('Playlist',playlistSchema);

and just use

.populate('videos')

instead of

.populate('[videos]')

Answer 2

const app = await this.appModel.findOne({ slug })
    .populate({
        path: 'category', 
        populate: {
           path: 'subCategories',
           model: 'Category',
           select: { name: 1, slug: 1, _id: 0 }
        },
     });