Hotmart Code Challenge – Reactive Version

Context: This project is my solution to a coding challenge from Hotmart, now implemented using Spring WebFlux to demonstrate a fully reactive, non-blocking architecture. Below is the original challenge description and requirements.

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Version

1.2.1

Context

Imagine you're a developer at a tech company, and your new task is to build part of a high-traffic product marketplace.

So far, you’ve received the description of the following entities:

• Product: ID, name, description, creation date
• Buyer: ID, name
• Seller: ID, name
• Product Category: ID, name
• Sale: ID, seller, buyer, product

When a buyer purchases a product, they can rate it from 0 to 5 (this rating is not yet mapped in the entities).

One of the most important parts of the marketplace being built is the product search feature. Each product will receive a daily ranking score calculated using the following formula:

X = Average rating of the product over the last 12 months  
Y = Number of sales / days the product has existed  
Z = Number of news articles related to the product category on the current day

Score = X + Y + Z

The Challenge

Your task is to:

• Create a CRUD (Create, Read, Update, Delete) for products.

• Build a Product API exposing the CRUD operations (list, find, delete, update, insert).

• Create a service to search for products ordered by ranking, filtered by name and category.

  • The service output must include the fields currentDate and searchTerm, along with the list of products matching the search. Each returned product must include: { id, name, description, creationDate, score }

• All services must be auditable.

Notes:

• To get the number of news articles for a given category, you can use the API at https://newsapi.org/. Model the entities accordingly to fit the scenario. Also, create initial data for these entities.
• You should query the https://newsapi.org/docs/endpoints/top-headlines endpoint 4 times a day, store the data locally, and use the publication date of each article to support the required logic.

What We Expect from Your Test

• We want to assess your technical skills, analytical thinking (preferably through short and clear commit messages), and how you present results.
• You don’t need to implement everything, but we want a clear sense of how you approach and solve problems.
• Feel free to include/modify/remove entities, attributes, technologies, jobs, or anything else necessary to better address the challenge.

Specifically, in your project delivery, we would like to see:

• Documentation
• Proper use of libraries
• Code written with clear semantics – readability is as important as performance
• Decoupling and a clear hierarchy among components
• Automated testing

Things That Would Impress Us

• Fault tolerance when calling the external News API
• Caching with a suitable library to improve query speed
• Pagination support in product listing
• Containerization using Docker
• Strategy to avoid excessive usage of the news API
• Automated tests beyond unit tests (e.g., integration, E2E)
• Use of a tool for versioning data loading scripts
• Good solution architecture, design patterns, and object-oriented or reactive programming
• Security for endpoints that persist data (e.g., in-memory auth)
• All code written in English

What We Don’t Want to See

• Code that clearly wasn’t written by you
• A project that misses the core objectives
• Poorly readable code
• Lack of documentation or run instructions

Evaluation Criteria

• Completion of proposed objectives
• Code semantics, structure, readability, maintainability, and scalability
• Project organization
• Architecture, design patterns, and use of WebFlux reactive principles
• Performance, resilience, and error handling
• API documentation
• Entity modeling

Requirements

• Use Java or Kotlin
• Do not use tools or databases requiring commercial licenses
• Each table must have at least 100 records