Defining the Domain Model in mediTurn

Foundation

Establishing a robust domain model is the cornerstone of any scalable application. In the sabrimassola/mediTurn project, the focus recently shifted toward formalizing the core domain entities. A well-defined model acts as the "single source of truth," ensuring that business logic is encapsulated correctly and that data integrity is maintained throughout the application lifecycle.

The Role of Domain Modeling

Think of a domain model as the architectural blueprint for a house. Just as you need to know where the load-bearing walls are before you start wiring electricity, you need to define your entities and their relationships before implementing complex service layers. By mapping out these relationships early, you reduce the risk of "anemic" objects—classes that hold data but lack the behavior necessary to enforce domain rules.

Implementation Strategy

In Java, creating a domain model involves leveraging clean object-oriented principles. By keeping entities focused on specific responsibilities, we ensure the codebase remains maintainable as new features are added. Here is an illustrative example of how one might structure a core entity:

public class Appointment {
    private UUID id;
    private LocalDateTime schedule;
    private Status status;

    public Appointment(LocalDateTime schedule) {
        this.id = UUID.randomUUID();
        this.schedule = schedule;
        this.status = Status.PENDING;
    }

    public void confirm() {
        if (this.status == Status.CANCELLED) {
            throw new IllegalStateException("Cannot confirm cancelled appointment");
        }
        this.status = Status.CONFIRMED;
    }
}

By placing validation logic like confirm() directly within the entity, we prevent invalid states from propagating to the database or other parts of the system.

Results

Completing the domain model for mediTurn provides a clear roadmap for subsequent development. Developers now have defined interfaces and entity states to work with, which simplifies the creation of repositories and service controllers.

Next Steps

With the domain model in place, the next logical step is to implement repository interfaces to manage persistence. Focus on keeping these layers decoupled so that your domain remains agnostic to the underlying storage technology.

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