Clean Architecture in Angular

Clean architecture is a software development approach that emphasizes the separation of concerns and the organization of code into distinct layers. The goal of clean architecture is to create a codebase that is easy to maintain, test, and extend over time.

In this article, we will discuss how to implement the clean architecture in an Angular application, and how it can help us write better code.

Overview of Clean Architecture

Clean architecture is based on the principle of separating the business logic of an application from the technical details of its implementation. This is achieved by organizing the codebase into distinct layers, each with a specific responsibility.

The layers of clean architecture are typically organized as follows:

1. Presentation Layer: This layer is responsible for handling user input and rendering output. In Angular, this layer corresponds to the components and templates that make up the UI of the application.
2. Application Layer: This layer is responsible for implementing the business logic of the application. It is responsible for coordinating the interactions between the presentation layer and the domain layer.
3. Domain Layer: This layer contains the core business logic of the application. It should be independent of any technical details or implementation details, and should represent the business rules and processes that the application is designed to support.
4. Infrastructure Layer: This layer is responsible for providing the technical details of the application’s implementation, such as data persistence, network communication, and external dependencies.

Implementing Clean Architecture in Angular

To implement the clean architecture in an Angular application, we can start by organizing our codebase into distinct modules, each corresponding to a layer of the architecture.

Here’s an example of how we can organize our codebase using clean architecture principles:

src/
├── app/
│ ├── presentation/
│ │ ├── components/
│ │ ├── templates/
│ ├── application/
│ │ ├── services/
│ ├── domain/
│ │ ├── models/
│ │ ├── services/
│ ├── infrastructure/
│ │ ├── services/
│ │ ├── data-access/
├── assets/
├── environments/

In this example, we have organized our codebase into four distinct layers: presentation, application, domain, and infrastructure. We have also separated our code into distinct modules, each with a specific responsibility.

Here’s a brief overview of each layer:

1. Presentation Layer

   The presentation layer contains the components and templates that make up the UI of the application. It is responsible for handling user input and rendering output.

   In Angular, we can implement the presentation layer using components and templates. We can also use services to handle any business logic that is specific to the UI.

2. Application Layer

   The application layer contains the services that implement the business logic of the application. It is responsible for coordinating the interactions between the presentation layer and the domain layer.

   In Angular, we can implement the application layer using services. These services should be responsible for coordinating the interactions between the presentation layer and the domain layer.

3. Domain Layer

   The domain layer contains the core business logic of the application. It should be independent of any technical details or implementation details and should represent the business rules and processes that the application is designed to support.

   In Angular, we can implement the domain layer using services and models. These services should be responsible for implementing the core business logic of the application, while the models should represent the data that the application operates on.

4. Infrastructure Layer

   The infrastructure layer contains the services that provide the technical details of the application’s implementation, such as data persistence, network communication, and external dependencies.

   In Angular, we can implement the infrastructure layer using services and data-access modules. These services should be responsible for implementing the technical details of the application’s implementation, such as communicating with external APIs or persisting data to a database.