c# Dependency Injection in onion architecture for NET Core

We are also using Docker Compose to group our Web application container with a container running the PostgreSQL database image. That way, we won’t need to have PostgreSQL installed on our system. Notice that we create a switch expression around the exception instance and then perform a pattern matching based on the exception type. Then, we are modifying the response HTTP status code depending on what the specific exception type is. Without this line of code, the Web API would not work.

Infrastructure Layer:

px” alt=”onion architecture .net core”/>https://www.1investing.in/ 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.

Clean architecture series — Part 3

It’s like we’re just creating interfaces that mirror those classes. If we add something to the class, we add it to the interface. By organizing the codebase according to this folder structure, developers can easily navigate and modify different components of the application. The folder structure promotes separation of concerns, with dependencies flowing inward, adhering to the dependency rule of Onion Architecture. Now we need to add a new project to our solution that will be the service layer.

• Onion architecture uses the concept of the layer but is different from N-layer architecture and 3-Tier architecture.
• The main idea is to use the access modifiers to ensure the architectural constraints.
• Using this approach, we can encapsulate all of the rich business logic in the Domain and Service layers without ever having to know any implementation details.
• If you have very complex business logic, it would make sense to encapsulate it inside of our domain entities.

Onion architecture solves the problem that we face during the enterprise applications like coupling and separations of concerns. Onion architecture also solves the problem that we confronted in three-tier architecture and N-Layer architecture. In Onion architecture, our layer communicates with each other using interfaces. From what I understand in the onion architecture, separate concerns in the same layer should not depend on one another. However, I also need to setup DI for my DbContext which is defined in the Persistence project of the same ring.

To keep it clear, in the above diagram we can see that the presentation layer depends on the logics layer, which in turn depends on the data access and so on. Onion Architecture is a software architectural pattern that promotes a modular and loosely coupled design, focusing on separation of concerns and maintainability. It helps developers create applications that are more flexible, testable, and easier to evolve over time. In this article, we will delve into the key concepts of Onion Architecture and provide an example folder structure that illustrates its implementation.

Few of the solutions developed and maintained by Microsoft MVPs like eShopOnWeb and eShopOnContainers also follow a similar (slightly more complicated variant of this approach). I have written a detailed article on API Versioning in ASP.NET Core 3.1 WebApi. Feel feel to read it to get a complete idea of this concept. And in the Startup class/ ConfigureServices method of the WebApi Just Add the following line. You can now see the advantage of this kind of approach.

In this article, We will talk about Onion Architecture In ASP.NET Core and its advantages. 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. You can find the source code of this implementation on my GitHub. 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.

We will start off by creating a Blank Solution on Visual Studio. PS, I use Visual Studio 2019 Comunity which is completely FREE. To keep things simple but demonstrate the architecture to the fullest, we will build an ASP.NET Core Web API that is quite scalable. For onion architecture .net core this article, Let’s have a WebApi that has just one entity, Product. We will perform CRUD Operations on it while using the Onion architecture. By now it should be obvious that the Presentation project will only have a reference to the Services.Abstraction project.

The flow of dependencies dictates what a certain layer in the Onion architecture can do. Because it depends on the layers below it in the hierarchy, it can only call the methods that are exposed by the lower layers. Testability is very high with the Onion architecture because everything depends on abstractions. The abstractions can be easily mocked with a mocking library such as Moq. To learn more about unit testing your projects in ASP.NET Core check out this article Testing MVC Controllers in ASP.NET Core. The Onion architecture is a form of layered architecture and we can visualize these layers as concentric circles.

When there is just a logical separation in your application, we can term it as layers or N Layers. In cases where there is both a physical and logical separation of concerns, it is often referred to as n-tiered application where n is the number of separations. In this article, we will deal with Layered Architecture.

The composition root then configures the application so that the concrete implementations are matched with the abstractions defined within the domain. When compiling, the domain does not depend on anything out of itself. Therefore, for example, the domain would not depend on the persistence project.

We don’t take some generic all-purpose repository interface and jam it into our domain. And that’s why I included it inside my template because it can be useful for anyone. Also, I didn’t want to introduce CQRS and Event Sourcing with difficult examples with different databases and propagating changes from the Write DB to the Read DB. It is just a simple “DataBase” (there is no database access, just creating mocked data inside the Repository implementation). Another option is to use tools that scan your source code to ensure architectural constraints or code reviews. They usually prefer the fast implementation approach over the long lasting and you often have to do a lot of effort to convince them.

It basically has the models/entities, Exception, validation rules, Settings, and anything that is quite common throughout the solution. To maintain structural Sanity in Mid to Larger Solutions, it is always recommended to follow some kind of architecture. You must have seen most of the Open Sourced Projects having multiple layers of Projects within a complex folder structure. Then we saw how the Service layer was created, where we are encapsulating our business logic. To make it straightforward to download the application code and be able to run the application locally we are using Docker. With Docker we are wrapping our ASP.NET Core application inside of a Docker container.

Also additional third party tools which will also live in the same ring, also need to be hooked up through the DI. 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. In this article, we will cover the onion architecture using the ASP.Net 6 Web API. Onion architecture term is introduced by Jeffrey Palermo in 2008.

Here is a simple diagrammatic representation of a variation of the N-Layer Architecture. The presentation Layer usually holds the Part that the User can interact with, i.e, WebApi, MVC, Webforms, and so on. Business Logic is probably the most important part of this entire setup. It holds all the logic related to the Business requirements. Now, every application ideally has its own dedicated Database.