Clean Architecture in Go: A Trader Monorepo with MongoDB

You’ll learn what ports and adapters are, why they exist and how they help decouple business logic from external systems like databases or APIs. We map these concepts directly into a Go folder structure.

You’ll understand how to initialize a MongoDB client properly, configure timeouts, handle context propagation and manage connections responsibly inside a Clean Architecture project.

This lesson explains ObjectIDs, how MongoDB generates them, how to use them in Go, how to convert them from strings and how they integrate with BSON and JSON tags.

We review one of the most common mistakes when mapping domain entities to database documents: coupling domain objects to BSON and JSON tags. You’ll learn how to prevent this and why it matters for long-term maintainability.

You’ll learn how to build transformers to convert entities into database models and vice versa. This ensures that domain logic stays pure while infrastructure remains flexible.

An overview of the testing pyramid, where unit tests, integration tests and end-to-end tests fit in and how Clean Architecture simplifies testing at every level.

You’ll write your first unit tests, learn about the testing package, error handling patterns and how to organize tests across files and packages.

You’ll learn how to use popular assertion libraries to write cleaner, more readable tests. This lesson shows when assertions help and when they don’t.

A deep dive into one of Go’s most important testing patterns: table-driven tests. You’ll learn how to run multiple scenarios cleanly and when to use this approach.

In this lesson, we're covering everything you need to know in order to run any test case or test package using just the terminal.

Execute tests in parallel, use only short tests, generate coverage reports, detect race conditions, everything you need to use the terminal as a pro.

You’ll implement the core logic for retrieving a Strategy by its ID using a port interface, ensuring clean separation between domain and infrastructure.

We introduce domain errors such as “strategy not found," invalid input errors and how to expose them consistently across layers.

You’ll implement the logic for creating a new strategy, validating input, preparing domain objects, and calling the repository.

You’ll learn how to manually create a fake repository for testing, helping you understand how mocks should behave before relying on automation tools.

A practical lesson on installing, configuring and using the mockery tool to generate mocks automatically based on your interfaces.

We complete the use case implementation by integrating real repositories, transformers and domain validation logic.

You’ll build the actual service layer that ties use cases together, preparing it for its usage in the HTTP transport integration.

In this lesson, we explore why Gin is one of the most popular and efficient HTTP frameworks in the Go ecosystem and why it's a great fit for Clean Architecture projects.

You’ll learn what Gin is, when it makes sense to use it instead of the standard net/http and how its routing, middleware system, performance, and developer-friendly APIs can significantly speed up backend development.

We’ll also cover how Gin fits perfectly inside a Clean Architecture project: how to keep handlers thin, how to map incoming HTTP requests to use cases, and how to wire Gin routes without coupling your domain or application layers to the framework.

By the end of the lesson, you’ll know exactly how to integrate Gin safely and cleanly as the transport layer of a scalable Go backend.

You’ll create the HTTP handler, decode JSON input, validate fields, call the use case and return a proper JSON response.

You’ll implement the handler that reads an ID from the URL, calls the use case, handles errors and renders JSON output.

You’ll set up routes, group endpoints, initialize controllers and ensure your transport layer remains independent from the rest of the application.

You’ll assemble all components: repositories, use cases and HTTP handlers into a cohesive application object following Clean Architecture principles.

You’ll build the real application entrypoint, initialize configuration, database and server.

You’ll learn how to manage environment variables for different environments (dev, prod), handling config defaults and safe loading patterns.

We launch the full backend for the first time, hitting endpoints from Postman, validating MongoDB integration and confirming everything works end-to-end.