It doesn’t depend much on the previous layers, so you can easily swap databases and other details. The main idea you should understand is group coupling. This is when layers depend on each other to work appropriately. In our case, there should always be an inward dependency. This means that the code should only depend on what’s closer to the center, ignoring “outside” layers. Having created a domain model and a web API, we needed to seamlessly connect them.
You could say that it’s another approach to solving a business problem. Onion architecture might seem hard in beginning but is widely accepted in the industry. It is a powerful architecture and enables easy evolution of software. By separating the application into layers, the system becomes more testable, maintainable and portable. It helps easy adoption of new frameworks/technologies when old frameworks become obsolete.
Today, we are going to cover uploading & downloading multiple files using ASP.Net Core 5.0 web API by a simple process.
The “Onion Architecture,” a well-known software design, has a number of benefits for both businesses and developers. Some of the main advantages of onion architecture are listed below. Giving software projects https://www.globalcloudteam.com/ a distinct structure and a separation of concerns, onion architecture can aid in achieving these objectives. This layer contains application entities and DB model classes which work independently.
- In 3-tier and n-tier architectures, none of the layers are independent; this fact raises a separation of concerns.
- Code should depend only on the same layer or layers more central to itself.
- In this post, we’ll examine the main principles, advantages, and application of onion architecture to your projects.
- Being a Microsoft certified engineer, he specializes in web development and has experience in creating desktop and mobile solutions.
- Now, it is time we moved on to the pros and cons of this type.
The Model is used to pass the data between View and Controller on which the business logic performs any operations. The Controller is used to handle the web request by action methods and returns View accordingly. Hence, it solves the problem of separation of concern while the Controller is still used to database access logic. In essence, MVC solves the separation of concern issue but the tight coupling issue still remains. Shown above is the proposed Onion Architecture, which has layers defined from core to Infrastructure. Well, in that case, I will have to either duplicate the business logic code to all the repositories implementing the contract.
Why do developers use onion architecture?
We will have to register IApplicationDBContext and bind it to ApplicationDbContext, right? Similar to the Application layer, we will have to create a new class just to register the dependencies and services of this layer to the service container. In software development, architecture plays a critical role in determining the quality, scalability, and maintainability of a software system.
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. With layered and hexagonal architectures understood, the time has come to talk about a relative – Onion Architecture, onion software architecture which puts a new spin on layers. Naturally, maybe you want to start the development by the database, but it’s a mistake! When working with Onion Architecture, you should always start developing the inner layers before the outer ones.
Generate the Migrations and the Database
The Infrastructure Layer uses them, but is does not create them. If you have a repository that expects a PostgreSQL client, the main should instantiate it and pass it to the repository during its initialization. It’s responsible for dealing with the persistence , and acts like a in-memory collection of domain objects. The Infrastructure Layer should not implement any business logic, as well as any use case flow. The former are rules that are executed to implement a use case of your application.
Why can’t the test assembly inject mock objects of these interfaces into the class under test just alike? It has access to the interfaces of the assembly as well. The obvious advantage of the Onion architecture is that our controller’s methods become very thin. We moved all of the important business logic into the Service layer. Yes, onion architecture is well-known in the programming world, and many applications use its principles.
Service Layer
Cloud services such as Microsoft Azure and database options including SQL Server and MSSQL are also frequently covered. Our fare calculation depends on external services such as routing information and fare models. Interfaces for these are defined in the Domain Services layer — IFareRepostory and IRouteService. RiderFareCalculator is implemented in this layer also, and it depends on the fare repository and route service interfaces declared in the same layer. Note that with this approach, we do not depend on the external service, rather the external service depends on our declared contracts.
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 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.
Briefly about Microservices
The purpose of the Presentation layer is to represent the entry point to our system so that consumers can interact with the data. We can implement this layer in many ways, for example creating a REST API, gRPC, etc. Services.Abstractions project it will only be able to call methods that are exposed by this project. We are going to see why this is very useful later on when we get to the Presentation layer. These are just some of the examples of what we could define in the Domain layer.
In the WebApi Project, Properties drill down, you can find a launchsettings.json file. This file holds all the configurations required for the app launch. Thus, the swagger will open up by default every time you run the application.
What is the Onion Architecture?
Great job with the architecture and thanks for sharing. There’s a problem with the template however that after authorizing and getting a valid token, the controllers with an attribute do not work, the error says “You are not authorized”. Can you try this yourself and see what the problem is? In practical scenarios, you would actually want both EFCore and RAW SQL Queries for optimal performance. While ADO.NET is super fast, it’s very ideal for long queries with tons of joins. Whereas, EFCore comes with a lot features without compromising much on the performance.