How to add multiple interface implementations via dependency injection without adding them one by one

Question

I am using .net core, I got a simple Interface something like :

public interface ITask
{
    string TaskName { get; }
    void Execute(TaskDetails item);
}

I got many classes which implement it, a sample class :

public class Task1Adapter : ITaskAdapter
{

    public string TaskName => "MyTask...";

    public void Execute(TaskDetails item)
    {
         var x = 1 + 1;
    } 
}

Then i got the DI section in which i add a line for each class -

services.AddSingleton<ITaskAdapter, Task1Adapter>();

My problem is that I got quite a lot of tasks and If possible I would rather avoid having 100+ AddSingleton lines.

Is there a way to somehow add all of the classes which implement that interface in one go without having to add AddSingleton logic for each new class I am adding?

Edit: Since I need to call different tasks / classes that implement the interface dynamically I used the following logic in run time -

private readonly IEnumerable<IFilesWorkerAdapter> _taskAdapter;
_taskAdapter.FirstOrDefault(e => e.TaskName== taskNameFromExternalSource).Execute();

You can use reflection to find all classes derived from that interface and add it to the services collection. — Nkosi
– Nkosi, Commented May 2, 2019 at 10:48
Use factory pattern to instantiate a concrete class of an interface. Profit serviceProvider to get the instance configured. @Nkosi comment will allow you to register each class but I advice you register the class not the pair Interface, Class. Make the factory to decide witch class to instantiate. — Alberto León
– Alberto León, Commented May 2, 2019 at 10:52
I added another part to the question to make it clearer. I not sure if your comment still valid with that in mind. Can you guys add a minimal example for the reflection logic? — Ivgi
– Ivgi, Commented May 4, 2019 at 15:04

Jhon Marmolejo · Accepted Answer · 2019-05-02 11:33:24Z

1

You can use Ninject with convention names. Check the following example:

https://github.com/jhonmarmolejo/DemoMVC/blob/master/Demo.MVC/App_Start/NinjectWebCommon.cs

In line number 57, I implemented all interfaces according to a specific rule

  /// <summary>
    /// Load your modules or register your services here!
    /// </summary>
    /// <param name="kernel">The kernel.</param>
    private static void RegisterServices(IKernel kernel)
    {
        kernel.Bind(ker =>
        {
            ker.FromAssembliesMatching("*Business.Implementation*").SelectAllClasses().BindAllInterfaces();
        });
    }

To use it, you'll need the following nuget:

https://www.nuget.org/packages/Ninject.Extensions.Conventions/

I hope it helps you Regards Jhon

answered May 2, 2019 at 11:33

Jhon Marmolejo

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1 Comment

Ivgi Over a year ago

Thank you for the answer, I am pretty deep with the 'native' supplied .net core DI logic and I dont want to make any big changes to that.

Jhon Marmolejo · Accepted Answer · 2021-04-16 09:11:18Z

0

Update of my previous response: .NET Core allows registering your implementations using reflection

        services.Scan(scan => scan
            .FromAssemblyOf<EmailService>()
            .AddClasses(classes => classes.Where(c => c.Name.EndsWith("Service")))
            .UsingRegistrationStrategy(RegistrationStrategy.Skip)
            .AsImplementedInterfaces()
            .WithSingletonLifetime());

You only need to do the following steps:

Indicate one class where the ServiceCollection needs to get the other implementations, in my case 'EmailService'.
To have a convention names, in my case "Service" at the end of the classes names.

answered Apr 16, 2021 at 9:11

Jhon Marmolejo

111 bronze badge

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