Basic nodejs back-end that exposes CRUD functionality and queries to a MongoDB collection using the library devextreme-query-mongodb.

• Download and install VirtualBox.
• Download and install Vagrant.
• Open a command line and change directory to the base path of this project.
• Execute the vagrant up command, once the process completes an Ubuntu-MongoDB virtual machine will be running.
• Continue to step 2.

mkdir C:\mongodb\data
mongod --replSet rs0 --dbpath "C:\mongodb\data"

mkdir -p /mongodb/data
mongod --replSet rs0 --dbpath /mongodb/data

Once the mongodb server is running you can continue and run this project

The Nodejs server is installed and automatically started within the Vagrant virtual machine. You should be able to access at:
http://localhost:8080/frontend

1. GET /grades: this endpoint uses the library devextreme-query-mongodb to format request/response parameters. So it can be used to test DevExtreme components.

2. (GET, POST, PUT, PATCH, DELETE) /api/grades: this endpoint exposes a basic CRUD functionality.

3. GET /grades/stream: This endpoint uses mongo Change Streams to respond with a Server-sent event when any operation (insert, update, delete) is performed on the Grades collection.

4. GET /frontend: This is an endpoint for testing the back-end endpoints. It responds with an HTML page that displays a list of Grades and dynamically updates the table when a notification (Server-sent event) is received.

You can start the nodejs server by running:
node app

Connect to mongosh
mongosh mongodb://localhost:27017/test

Then within mongosh To update a single document:

db.grades.updateOne( 
   { quizScore: { $gte: 90 } }, 
   [{ $set: { examScore: { $round: [ { $multiply: [ { $rand: {} }, 100 ] }, 2 ] } } }]
);

To update multiple documents:

try {
   db.grades.updateMany(
      { examScore: { $lte: 25 } },
      [{ $set: { examScore: { $round: [ { $multiply: [ { $rand: {} }, 100 ] }, 2 ] } } }],
   );
} catch (e) {
   print(e);
}

• https://ryantravitz.com/2018-11-29-server-sent-events/
• https://community.devexpress.com/blogs/oliver/archive/2017/04/03/devextreme-real-world-patterns-devextreme-widgets.aspx