The contract for IGeoLocation doesn’t mention any details of the underlying infrastructure. The actual implementation, within Supermarket.Infrastructure.Http.Clients, uses the Google Maps API but you wouldn’t know it from looking at the interface. This is done on purpose since the Domain Entities and Interfaces don’t need to know anything about the implementation details. The details of the Maps API call are hidden by making Google’s API contract internal to Supermarket.Infrastructure.Http.Clients. The name Onion Architecture was originally coined by Jeff Palermo, but has since gone under lots of other pseudonyms. Ports and Adapters, Hexagonal Architecture and Clean Architecture are all different names for effectively the same thing.
Create a new ASP.NET Core Web API Project
As you can see, we mark the service implementations with the internal keyword, which means they will not be publicly available outside of onion architecture .net core the Services project. As we can see, it consists of the Web project, which is our ASP.NET Core application, and six class libraries. The Domain project will hold the Domain layer implementation.
In this layer, we add our third party libraries like JWT Tokens Authentication or Serilog for logging, etc. so that all the third libraries will be in one place. In our project, we have implemented almost all important libraries, you can plug & play (add/remove) based on your project requirement in StartUp.cs file. So we have entities again, and repository interfaces again. But notice the CleanArchitecture.PizzaStore.Application project. It contains specific use cases, that we want the application to fulfill. Discussing AI software development, and showing off what we’re building.
Step 1: Download extension from project template
We have now the knowledge of how the layer communicates with each other’s in onion architecture and how we can write the Generic code for the Interface repository and services. Now we can develop our project using onion architecture for API Development OR MVC Core Based projects. This layer lies in the center of the architecture where we have application entities which are the application model classes or database model classes. Using the code first approach in the application development using Asp.net core these entities are used to create the tables in the database.
- We will also together build a WebApi that follows a variant of Onion Architecture so that we get to see why it is important to implement such an architecture in your upcoming projects.
- With Onion Architecture, the game changer is that the Domain Layer (Entities and Validation Rules that are common to the business case ) is at the Core of the Entire Application.
- However, in the OnModelCreating method, we are configuring our database context based on the entity configurations from the same assembly.
- The name Onion Architecture was originally coined by Jeff Palermo, but has since gone under lots of other pseudonyms.
Step 1. Create Project Structure
- The Domain project will hold the Domain layer implementation.
- Now we need to add the student controller that will interact will our service layer and display the data to the users.
- Remember that we have two abstract exception classes BadRequestException and NotFoundException inside of the Domain layer?
- I will be implementing a CRUD (Create, Read, Update, Delete) operation in an ASP.NET Core Web API using the Onion Architecture and Prototype Design Pattern.
- We can be more or less strict, depending on our needs.
You must have seen most of the Open Sourced Projects having multiple layers of Projects within a complex folder structure. But here we need to add the project reference of the Domain layer in the repository layer. Write click on the project and then click the Add button after that we will add the project references in the Repository layer. We will follow the same project as we did for the Domain layer. Add the library project in your application and give a name to that project Repository layer.
Adding Swagger To WebApi Project
In the Startup.cs file, configure dependency injection. Install Microsoft.EntityFrameworkCore.Design package in OnionArchitectureGuide.Api project, for the migration to work. Create a file named ApplicationServiceExtensions.cs in the root level of the OnionArchitectureGuide.Application.Implementation project. This whiteapp contains following features, uncheck feature need to implement yet. In the Startup.cs file, configure dependency injection and middleware. Onion Architecture, introduced by Jeffrey Palermo, is structured in concentric layers, where.
That’s quite everything in this simple yet powerful implementation of Onion Architecture in ASP.NET Core. This will be an Empty API Controller which will have API Versioning enabled in the Attribute and also a MediatR object. We will not have to re-define the API Versioning route or the Mediator object. But we will just add the BaseAPI Controller as the base class. Remember we created an IApplicationDBContext Interface in the Application Layer? Create a new folder named Context and add a new class ApplicationDbContext.
A key principle here is that the dependencies flow inwards. This allows specific implementations to be changed in the future without impacting other parts of the application. “Adapters” are responsible for implementing these interfaces and connecting the application to external systems or frameworks. However the principles are essentially the same, so from here on out we’ll be focusing on onion. It’s worth noting here that this pattern is sometimes referred to as the “Hexagonal Architecture” or “Ports and Adapters Architecture”. Conceptually, the infrastructure and presentation layers are considered to be at the same level in the hierarchy.
The presentation layer, once again similar to the onion architecture, is responsible for handling user interactions and displaying data to the user interface. This architecture is particularly useful for larger applications where maintainability and testability are crucial. By adhering to Onion Architecture principles, you can build robust, scalable applications in .NET Core that are well-organized and easy to maintain over time. Let’s build a Product and Order service using Onion Architecture.
We will have to register Swager within the application service container. Navigate to ../Startup.cs and add these lines to the ConfigureServices method. Next, let’s go to the Infrastructure Folder and add a layer for Database, (EFCore). Now we can see when we hit the GetAllStudent Endpoint we can see the data of students from the database in the form of JSON projects.
Setting Up the Project
The domain layer, identical to the onion architecture layer, represents the core business rules and entities. However, we are going to do something different from what you are normally used to when creating Web APIs. By convention, the controllers are defined in the Controllers folder inside of the Web application.Why is this a problem? Because ASP.NET Core uses Dependency Injection everywhere, we need to have a reference to all of the projects in the solution from the Web application project.
Remember that we have two abstract exception classes BadRequestException and NotFoundException inside of the Domain layer? Great, we saw how we wired up all of the dependencies of our application. However, there are still a couple of things to take care of. We did not see how to wire up any of our dependencies.
CQRS and Event Sourcing
Supermarket.Http.Utilities is named differently from the other projects. Its classes aren’t domain specific and are generic enough that they can be used in many different contexts. In a real world application you’d probably want the project to be part of a NuGet package that it can be used where needed.
In order to access the Database, we introduce a Data Access Layer. This layer usually holds ORMs for ASP.NET to fetch/write to the database. There are more examples, but hopefully, you get the idea.
We have connected all of our Onion architecture implementation layers, and our application is now ready for use. We’ve shown you how to implement the Domain layer, Service layer, and Infrastructure layer. Also, we’ve shown you the Presentation layer implementation by decoupling the controllers from the main Web application. As you can see, the implementation is extremely simple.
