Intro

Welcome to the Cozero coding challenge!

Our idea is to offer you a fun and practical challenge so that we can later use it as a conversation starter to go over your thought process.

Cozero Challenge

We created a very simple MVP for an app where users can signup and list their carbon emission offsetting projects. The current functionality includes:

• Users can register/login into the app
• Users can post projects
• Anyone can see projects

Stack

• Frontend: ReactJS
• Backend: NestJS + TypeORM + MySQL.

Before run

You need:

• Node version >= 12.
• Docker

How to run

MySQL in Docker

docker-compose up -d

Backend running on port 3001

cd cozero-backend
npm i
npm run dev

Frontend running on port 3000

cd cozero-frontend
npm i
npm run dev

Requirements

We need to build upon our MVP and fix some bugs.

Improvements

• We need to be able to search for projects. Create an API endpoint that searches for projects by their title/description. The API response should be with the same fields as the listing project.

• Currently, when making a request to create a new project we can omit the listing proposal field. We need to make the field listing proposal required.

• We realized that some of the clients sometimes would mistakenly delete projects. Our clients are not tech-savvy so it would be great if we can find a way to retrieve projects that were deleted mistakenly.

Questions

• How would you make sure the emails provided from the users are real?
• After running the app for a while, we suddenly get a huge influx of new projects. We currently have over 5.000.000 projects in our database. The response time of the /projects endpoint went from 50ms to 3s. Assuming the frontend is fetching data per language and within specific timeframe (from - to date), what would you do in oder to make the app faster? E.g. request from the frontend -> GET /projects?language=${lang}&createdAtGreaterThan=${date}&createdAtLowerThan=${date}
• What else can we do in order to improve the time?
• What kind of metrics would you collect from your application to know that everything is OK?

How to submit

1. Create a PR and commit your changes
2. Assign it back to your hiring manager
3. Send an email with an answer to the questions and a confirmation that you're done with the challenge

What happens next

• We'll set up a follow-up call and check with you about your availability