How to creating custom interfaces and injecting them into your application

There are following steps for creating interface and use it in a dependency injection:

1. Create a new interface in your project. For example, let’s create a simple interface named ITimeService:

public interface ITimeService
{
    DateTime GetCurrentTime();
}

2. Implement the interface in a new class. For example, let’s create a class named TimeService:

public class TimeService : ITimeService
{
    public DateTime GetCurrentTime()
    {
        return DateTime.Now;
    }
}

3. Register the service in the ConfigureServices method of your Startup class:

public void ConfigureServices(IServiceCollection services)
{
    services.AddTransient<ITimeService, TimeService>();
}

In this example, we are registering the TimeService implementation of the ITimeService interface as a transient service. This means that a new instance of the service will be created each time it is requested.

4. Inject the service into a controller using constructor injection. For example:

public class HomeController : Controller
{
    private readonly ITimeService _timeService;

    public HomeController(ITimeService timeService)
    {
        _timeService = timeService;
    }

    public IActionResult Index()
    {
        var currentTime = _timeService.GetCurrentTime();
        return View(currentTime);
    }
}

In this example, we are injecting the ITimeService instance into our HomeController using constructor injection. This allows us to use the GetCurrentTime method of the service inside the Index action of our controller.

Overall, creating custom interfaces and injecting them into your application is a key aspect of building modular and maintainable ASP.NET Core applications.