Book Image

Get Your Hands Dirty on Clean Architecture - Second Edition

By : Tom Hombergs
4 (1)
Book Image

Get Your Hands Dirty on Clean Architecture - Second Edition

4 (1)
By: Tom Hombergs

Overview of this book

Building for maintainability is key to keep development costs low (and developers happy). 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. Building upon the success of the first edition, this comprehensive guide explores the drawbacks of conventional layered architecture and highlights the advantages of domain-centric styles such as Robert C. Martin's Clean Architecture and Alistair Cockburn's Hexagonal Architecture. Then, the book dives into hands-on chapters that show you how to manifest a Hexagonal Architecture in actual code. You'll learn in detail about different mapping strategies between the layers of a Hexagonal Architecture and see how to assemble the architecture elements into an application. The later chapters demonstrate how to enforce architecture boundaries, what 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. Whether you're a seasoned developer or a newcomer to the field, "Get Your Hands Dirty on Clean Architecture" will empower you to take your software architecture skills to new heights and build applications that stand the test of time.
Table of Contents (18 chapters)

Validating input

Now, we’re talking about validating input, even though I just claimed that it’s not the responsibility of a use case class. I still think, however, that it belongs in the application layer, so this is the place to discuss it.

Why not let the calling adapter validate the input before sending it to the use case? Well, do we want to trust the caller to have validated everything as needed for the use case? Also, the use case might be called by more than one adapter, so the validation would have to be implemented by each adapter, and one might get it wrong or forget it altogether.

The application layer should care about input validation because, well, otherwise it might get invalid input from outside the application core. This might cause damage to the state of our model.

But where do we put the input validation if not in the use case class?

We’ll let the input model take care of it. For the Send money use case, the input model is the SendMoneyCommand...