Storing and replaying messages using MongoDB

Currently, if a new user joins the chat, they will not see any messages until someone actively sends messages. As such, new users will not be able to participate well in ongoing discussions. To solve this issue, we can store messages in the database and replay them when a user joins.

Creating the Mongoose schema

Follow these steps to create a Mongoose schema for storing chat messages:

1. Copy the existing ch14 folder to a new ch15 folder, as follows:

   $ cp -R ch14 ch15

2. Open the new ch15 folder in VS Code.
3. Create a new backend/src/db/models/message.js file.
4. Inside it, define a new messageSchema, which we are going to use to store chat messages in the database:

   import mongoose, { Schema } from 'mongoose'
   const messageSchema = new Schema({

5. The message schema should contain username (person who sent the message), message, a room that it was sent in, and a sent date for when the message was sent:

     username...