Dependency Injection in .Net Core Console

To demonstrate Dependency Injection in a .Net Core Console project, I will create a SecurityService class which will have a dependency on an AuditService class.

The SecurityService will allow a user to login, and then use the AuditService to write an audit log entry (in this case just to the console).

Each of these class will have a corresponding Interface.

Interfaces:

public interface ISecurityService
{
	void Login();
}

public interface IAuditService
{
	void Log();
}

The implementation of these interfaces are:

public class SercurityService : ISecurityService
{
	private readonly IAuditService _auditService;

	public SercurityService(IAuditService auditService)
	{
		_auditService = auditService;
	}
	
	public void Login()
	{
		Console.WriteLine("Log user in");
		_auditService.Log();
	}
}

public class AuditService : IAuditService
{
	public void Log()
	{
		Console.WriteLine("Audit action");
	}
}

To wire all this up we need to add the following NuGet package to our project:

Microsoft.Extensions.DependencyInjection;

The Dependency Inject is wired up as follows:

class Program
{
	static void Main(string[] args)
	{
		//Register the services
		var serviceProvider = new ServiceCollection()
			.AddSingleton<ISecurityService, SercurityService>()
			.AddSingleton<IAuditService, AuditService>()
			.BuildServiceProvider();
	
		//Instantiate the security helper, and call the login method
		var secutityHelper = serviceProvider.GetService<ISecurityService>();
		secutityHelper.Login();
	
		Console.Read();
	}
}

This will give the following output:

Log user in
Audit action