From Spaghetti Code to a Solid Project Structure

A successful software project is not just about making features work. It’s about ensuring that the codebase remains scalable, maintainable, and easy to extend as the project grows.

One of the most common challenges in software development is the rise of spaghetti code when presentation, data, and logic are all tangled together in a messy, interdependent system.

To solve this, developers turn to more structured approaches, often inspired by Clean Architecture. In this article, we’ll explore what spaghetti code is, why it’s problematic, and how applying a better project structure can transform long-term development.

What Is Spaghetti Code?

Spaghetti code refers to code with no clear structure or separation of concerns. Its main characteristics include:

• Business logic, database queries, and UI code all crammed into the same place.

• High interdependence of different components.

• Difficulty in debugging and testing.

• A high risk of breaking existing features when making small changes.

While this style of coding might be acceptable for quick prototypes or very small projects, it quickly becomes a nightmare when requirements expand.

Why Structure Matters

A well-organized project prevents the pitfalls of spaghetti code by introducing layers with defined responsibilities. According to principles derived from Clean Architecture, good code should be:

• Framework-independent (not locked into one library or tool).

• Database-independent (you can swap databases if needed).

• UI-independent (business logic doesn’t depend on screen design).

This separation ensures each part of the system can evolve without breaking everything else.

Layers of a Structured Project

A well-structured project often consists of the following layers:

1. Entities (Core Business Rules)

• Defines the fundamental rules and models of the application.

• Independent of frameworks or external systems.

2. Use Cases (Application Logic)

• Encapsulates specific operations, such as “Register User” or “Process Order”.

• Determines how business rules interact with each other.

3. Interface Layer (Controllers / APIs / UI)

• Handles inputs like HTTP requests or user actions.

• Transforms them into a format the application logic can understand.

4. Infrastructure Layer (Databases / External Services)

• Includes storage systems, APIs, and frameworks.

• Designed to be replaceable without impacting the core logic.

Example: Refactoring User Registration

Before (Spaghetti Code):
One big function handles everything: validation, database operations, business rules, and generating responses. A small change risks breaking unrelated parts of the system.

After (Structured Code):

• Validation logic is separated into its own module.

• Business rules live in a use case.

• Database operations are handled by the infrastructure layer.

• The controller only coordinates the flow between these parts.

This structure ensures readability and makes it possible to, for example, swap databases or update validation rules without affecting the rest of the code.

Advantages of Better Structure

• Scalability → Add new features by extending existing layers instead of rewriting code.

• Maintainability → Cleaner, more readable code reduces long-term complexity.

• Testability → Business logic can be tested in isolation, without depending on frameworks or databases.

• Flexibility → Swap out frameworks, UI libraries, or databases with minimal changes to the core logic.

Conclusion

Spaghetti code may seem acceptable in the short term, but it becomes a major obstacle as projects grow. By adopting a solid project structure inspired by Clean Architecture, developers can build applications that are robust, scalable, and easy to maintain.

This approach reduces complexity, increases testability, and lays the foundation for long-term software success.