Developing a C# WebApi on Domain-Driven Design (DDD) in .Net6 using Clean Architecture

Developing a WebAPI based on Domain-Driven Design (DDD) in .NET6 involves creating a solution with separate projects for each layer of the application and using Clean/Hexagonal/Onion (CHO) architecture to design the whole structure of the system, with the “domain core” being isolated in it’s separate modules.

The concept of DDD helps in the design of this “domain core” in collaboration with domain experts and possibly by using DDD concepts like Entites and Aggregates. Here are the steps you can follow to create a WebAPI using DDD in .NET6:

Requirements* Please make sure you have installed the following:

Visual Studio Code

.Net6 SDK

1. Create a new solution with the name of your choice.

Create a project folder for development: Eg. C:\Dev\DealSnapDDD.

Open CMD prompt in windows, go to your development folder and type:

C:\Dev\DealSnapDD>dotnet new sln -o DealSnapDDD(SolutionName).

You will get a message : The template “Solution File” was created successfully.

2. Create 2 projects for the Presentation layer. The Web Api and Contract

These 2 projects  represent the presentation layer and will contain web api and contract projects

In cmd type:
C:\Dev\DealSnapDDD>dotnet new webapi -o DealSnapDDD.Api

Then type:

C:\Dev\DealSnapDDD>dotnet new  -o DealSnapDDD.Api

3. Create a project for the Application layer.

This project will contain the application services that orchestrate the interaction between the Domain and Infrastructure layers.

In CMD type: dotnet new classlib -0 DealSnapDDD.Application

4. Create a project for the Infrastructure layer.

This project will contain the implementation of the repositories, data access logic, and external service integrations.

In CMD type: dotnet new classlib -0 DealSnapDDD.Infrastructure

5. Create a project for the Domain layer.

This project will contain all the business logic, entities, and value objects of your application.

In CMD type: dotnet new classlib -0 DealSnapDDD.Domain

6. Add projects to solution then build the solution.

Add the projects to your solution. In CMD type:

FOR /R %i IN (*.csproj) DO dotnet sln add "%i"

Once you have added the projects to the solution, in the comand prompt go into the main project folder (C:Dev\DealSnapDDD) and type: dotnet build

7. Add references to projects

First create dependency from API to Contracts and Application layer. In CMD type :

dotnet add .\DealSnapDDD.Api\ reference .\DealSnapDDD.Contracts\ .\DealSnapDDD.Application\

Next add the dependencie of the Infrastructure to the Application. Type:

dotnet add .\DealSnapDDD.Infrastructure\ reference .\DealSnapDDD.Application\

Add the dependency of the Application Layer to the Domain Layer. Type:

dotnet add .\DealSnapDDD.Application\ reference .\DealSnapDDD.Domain\

Finally add the dependency from the Api Layer to the Infrastructure layer

dotnet add .\DealSnapDDD.Api\ reference .\DealSnapDDD.Infrastructure\

Cogratulations! Once you have completed the steps above you have created the basic steps towards a Domain-Driven Design solution and you can now begin to code your WebApi.