How to connect user model with profile model in nodejs - node.js

Question

I am new to backend development And I am facing some issues with connecting User model with Profile model. And I also want to auto-generate username in profile model when user sets them in User model. I am not sure how to do this. Here is my code
Resolver.js
Mutation: {
signUpUser: async (parent, { userInput }) => {
const { email, username, password } = userInput;
const errors = [];
if (!validator.isEmail(email)) {
errors.push({
message: "Invalid Email",
});
}
const existingUser = await User.findOne({ email: email });
if (existingUser) {
const error = new Error("User exists already");
throw error;
}
if (errors.length > 0) {
const error = new Error("Invalid Input");
error.data = errors;
error.code = 402;
throw error;
}
const hashedPassword = await bcrypt.hash(password, 12);
const user = new User({
email: email,
password: hashedPassword,
username: username,
});
const createdUser = await user.save();
return {
...createdUser._doc,
_id: createdUser._id.toString(),
};
},
UserModel
const mongoose = require("mongoose");
const Schema = mongoose.Schema;
const userSchema = new mongoose.Schema(
{
email: {
type: String,
required: true,
},
password: {
type: String,
required: true,
},
username: {
type: String,
required: true,
},
status: {
type: String,
default: "I am new!",
},
posts: [
{
type: Schema.Types.ObjectId,
ref: "Post",
},
],
profile: {
type: Schema.Types.ObjectId,
ref: "Profile",
},
},
{ timestamps: true }
);
module.exports = mongoose.model("User", userSchema);
ProfileModel
const mongoose = require("mongoose");
const Schema = mongoose.Schema;
const profileSchema = new mongoose.Schema(
{
firstName: {
type: String,
default: null,
},
lastName: {
type: String,
default: null,
},
bio: {
type: String,
default: null,
},
profilePic: {
type: String,
default: null,
},
username: {
type: String,
default: null,
},
url: {
type: String,
default: null,
},
user: {
type: Schema.Types.ObjectId,
ref: "User",
}
},
{ timestamps: true }
);
module.exports = mongoose.model("Profile", profileSchema);
Here is the complete code if you like to give it a look
https://github.com/adityakmr7/medium-clone
Any help would be great. Thank you.
I am using Graphql here and apollo.