Book Image

Get Your Hands Dirty on Clean Architecture

By : Tom Hombergs
Book Image

Get Your Hands Dirty on Clean Architecture

By: Tom Hombergs

Overview of this book

Building for maintainability is key to keeping development costs low and processes easy. The second edition of Get Your Hands Dirty on Clean Architecture is here to equip you with the essential skills and knowledge to build maintainable software. With this comprehensive guide, you’ll explore the drawbacks of conventional layered architecture and the advantages of domain-centric styles such as Robert C. Martin's Clean Architecture and Alistair Cockburn's Hexagonal Architecture. Then, you’ll dive into hands-on explanations on how to convert hexagonal architecture into actual code. You'll learn in detail about different mapping strategies between the layers of hexagonal architecture and discover how to assemble the architectural elements into an application. Additionally, you’ll understand how to enforce architecture boundaries, which shortcuts produce what types of technical debt, and how, sometimes, it is a good idea to willingly take on those debts. By the end of this second edition, you'll be armed with a deep understanding of the hexagonal architecture style and be ready to create maintainable web applications that save money and time.
Table of Contents (13 chapters)

Different Input Models for Different Use Cases

We might be tempted to use the same input model for different use cases. Let's consider the use cases "Register Account" and "Update Account Details." Both will initially need almost the same input, namely some account details such as a description of the account.

The difference is that the "Update Account Details" use case also needs the ID of the account to be able to update that specific account. And the "Register Account" use case might need the ID of the owner, so that it can assign it to him or her. So, if we share the same input model between both use cases, we'd have to allow a null account ID to be passed into the "Update Account Details" use case and a null owner ID to be passed into the "Register Account" use case.

Allowing null as a valid state of a field in our immutable command object is a code smell by itself. But more importantly, how are we handling input validation...