Moongoose populate method returning an empty array - node.js

Question

I am trying to fetch the blogs that a user has posted using mongoose populate method but not able to do so but when I try to look for the user who posted a blog I am able to do so. Tell me what I am doing wrong.
const mongoose = require("mongoose");
const Schema = mongoose.Schema;
const userSchema = new Schema({
username: {
type: String,
required: true,
},
email: {
type: String,
required: true,
unique: true,
},
password: {
type: String,
required: true,
},
blogPosts: [{ type: mongoose.Types.ObjectId, ref: "Blogs", required: true }],
});
const Users = mongoose.model("Users", userSchema);
module.exports = Users;
This is my user model
const mongoose = require("mongoose");
const Schema = mongoose.Schema;
const blogSchema = new Schema({
title: {
type: String,
required: true,
},
description: {
type: String,
required: true,
},
image: {
type: String,
required: true,
},
user: {
type: mongoose.Types.ObjectId,
ref: "Users",
required: true,
},
});
const blogs = mongoose.model("Blogs", blogSchema);
module.exports = { blogs, blogSchema };
this is my blogs model
router.get("/users/:id", async (req, res) => {
let userBlogs;
try {
userBlogs = await users.find({ _id: req.params.id }).populate("blogPosts");
if (!userBlogs) {
return res.status(404).json({ msg: "No user found" });
}
return res.status(200).json(userBlogs);
} catch (err) {
return res.status(500).json({ err });
}
});
this is the route that I use for fetching all the blogs that a user has posted.This is just sending me back an empty posts array.
router.post("/newBlog/:id", async (req, res) => {
let blogAuthor;
try {
blogAuthor = await users.findOne({ _id: req.params.id });
} catch (err) {
return res.status(404).json({ message: "user not found" });
}
const newBlog = blogs({
title: req.body.title,
description: req.body.description,
image: req.body.imageUrl,
user: blogAuthor._id,
});
try {
await blogAuthor.blogPosts.push(newBlog);
await newBlog.save();
return res.status(200).json(blogAuthor.blogPosts);
} catch (err) {
return res.status(500).json(err);
}
});
the above is the route that I use to add new blog to the db.
router.get("/allBlogs", async (req, res) => {
let allBlogs;
try {
allBlogs = await blogs.find({}).populate("user");
} catch (err) {
return res.status(404).json(err);
}
res.status(200).json(allBlogs);
});
this is the route that sends all the blogs posted by all the users.
Interesting thing is that when I try to populate the user of a blogpost that is working exactly as expected it is populating the user of the blog from the users model however when I try to do the reverse that's not working. It is not populating all the blogs that a user has posted.