POPULATION ISSUE: Mongoose/Express - node.js

Question

I'm trying to have each record attached to a user who created it,
and every user have their records attached.
Here are my schemas:
1.The Records schema:
const mongoose = require('mongoose')
const RecordsSchema = new mongoose.Schema(
{
Title: { type: String, required: true },
postedby:[{
type: mongoose.Schema.Types.ObjectId,
ref: 'user'
}],
Author: { type: String, required: true},
ISBN: { type: String, required: true },
Review: { type: String },
SelectedFile: { type: String },
Likes: { type: Number, default:0},
Date: { type: Date, default: Date.now()}
});
module.exports = Records = mongoose.model('record', RecordsSchema', 'record');`
Here is the The user Schema:
const mongoose = require('mongoose')
const userSchema = new mongoose.Schema(
{
username: { type: String},
email: { type: String, required: true ,unique:true},
records:[{
type: [mongoose.Schema.Types.ObjectId],
ref: 'record' }],
password: { type: String, required: true},
Date: { type: Date, default: Date.now(), immutable: true }
});
module.exports = User = mongoose.model('user', userSchema,'user');
The express route for getting a record:
router.get('/postedby/', (req, res) => {
Records.find(req.params.id)
.populate('postedby')
.exec()
.then(post =>{
if (!post) {
return res.status(400).json({ msg: 'Add Posts' });
}
else return res.json(post);
}).catch (err => console.error(err))
});
Result of the route:
{
"postedby": [],
"Likes": 0,
"_id": "5fed8c12a4fb2c1e98ef09f6",
"Title": "New Age",
"Author": "Situma Prisco",
"ISBN": "23422",
"SelectedFile": "",
"Review": "",
"Date": "2020-12-31T08:30:10.321Z",
"__v": 0
},
I'm getting a blank Array on the populated user field(posteddby) .
Please help, What am I doing wrong? And yes, i do have a User Logged in

Answer 1

You are too close.
In your schema definition, postedby field itself is an array. Hence you can simply define it like :
postedby:[{
type: mongoose.Schema.Types.ObjectId,
ref: 'user'
}]
Make sure that the ObjectID is stored properly in the postedby array.
Also, you are trying to find a single record based on the ID, hence you can use findById(req.params.id) or findOne({_id:req.params.id}) which would return a single document.