Poll Creator

A poll creator using Fastify, Redis and real time voting results with WebSockets

Key Features • Motivation • How To Use • Credits • License

Key Features

• Create a poll with title and the options to vote using PostgreSQL with Prisma as a ORM.
• Get the poll created with number of votes ranked.
• Voting on a poll, the number of each votes will be stored using Redis as a database.
• When accessing the WebSocket endpoint, you will subscribe to the results of this poll.
• Everytime you vote, if a WebSocket connection is estabilished, all subscribers get the results in real time.

Motivation

How real-time communication works is important, many modern applications and services works with WebSockets, e.g. real-time chat. I learned the Pub/Sub pattern, when a Subscriber makes an inscription on a channel or topic and a Publisher publishes the message in this channel and the Subscribers consumes this message. For that application, using Redis as an in-memory database was very important to learn the use-cases of this database and, because of its fast read and write operations, it is one of the first choices on a chat application and message systems.

How To Use

• To clone and run this application, you'll need Git, Node.js (which comes with npm) and Docker with Docker Compose installed on your computer. From your command line:

  # Clone this repository
  $ git clone https://github.com/evans-costa/polls-realtime.git
  
  # Go into the repository
  $ cd polls-realtime

  # Install dependencies
  $ npm install

• Rename the .env.example file to .env and fill it accordingly:

  PORT=<YOUR_PORT>
  
  POSTGRES_USER=local_user
  POSTGRES_PASSWORD=local_password
  POSTGRES_DB=polls
  POSTGRES_PORT_NUMBER=54325
  
  DATABASE_URL=postgresql://local_user:local_password@localhost:54325/polls?schema=public
  
  SECRET_KEY=<YOUR_SECRET_KEY>

• Run the command to up Postgres and Redis containers:

  # Up the containers
  $ npm run services:up

  This will up a Redis and a PostgreSQL container on your Docker installation.

• Run the Prisma migrations:

  # Run the migrations
  $ npm run migrate:dev

• Run the server:

  # Run the project
  $ npm run dev

• If you would like to access the database by a GUI, Prisma comes with a built-in GUI to view and edit the data, from your command line:

  # Access the Prisma Studio
  $ npm run prisma:studio

• Now you can test it in your favorite API Testing Platform (Insomnia, Postman, Hoppscotch)

HTTP endpoints

• The API will be accessible at http://localhost:3000 (or in the port setted in .env file)

• The API provides the following HTTP endpoints and the body requests / responses:

  Creating a poll:

  POST /polls

  • Request Body:

    {
      "title": "Qual melhor framework web para NodeJS?",
      "options": ["Express", "Fastify"]
    }

  • Response Body:

    {
      "pollId": "194cef63-2ccf-46a3-aad1-aa94b2bc89b0"
    }

  Creating a vote on a poll:

  POST /polls/{pollId}/votes

  • Request Body:

    {
      "pollOptionId": "c5271ca0-3c5b-4a81-af94-284bfbfd49b1"
    }

  Get a poll by its ID:

  GET /polls/{pollId}

  • Response Body:

    {
      "poll": {
        "id": "194cef63-2ccf-46a3-aad1-aa94b2bc89b0",
        "title": "Qual a melhor framework web para NodeJS?",
        "options": [
          {
            "id": "c5271ca0-3c5b-4a81-af94-284bfbfd49b1",
            "title": "Express",
            "score": 2
          },
          {
            "id": "780b8e25-a40e-4301-ab32-77ebf8c79da8",
            "title": "Fastify",
            "score": 1
          }
        ]
      }
    }

WebSocket endpoint

• The WebSocket endpoint is at:

  ws://localhost:3000/polls/{pollId}/votes

• Everytime when voted on a poll, the WebSocket endpoint will publish the following message:

  {
    "pollOptionId": "c5271ca0-3c5b-4a81-af94-284bfbfd49b1",
    "votes": 2
  }

Credits

This project was made for NLW #14 Expert by Rocketseat and uses the following open source packages:

• Node.js
• Prisma
• Redis
• Fastify

License

The MIT License (MIT) 2024 - Evandro Costa. Please have a look at the LICENSE for more details.

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GitHub @evans-costa  ·  LinkedIn @evandro-souzac