Is it possible to add all IHostedService classes with a loop (ASP.NET Core 6)?-CodePudding

Is it possible to add all IHostedService implemented classes in a loop without adding them individually in ASP.NET Core 6?

Let's say we have this two implementations:

public class FirstImplementationOfHostedService : IHostedService 
{
    // ...
}

public class SecondImplementationOfHostedService : IHostedService 
{
    // ...
}

The default way in Program.cs to add them is:

builder.Services.AddHostedService<FirstImplementationOfHostedService>();
builder.Services.AddHostedService<SecondImplementationOfHostedService>();

But, what about having a hundred implementations?

There has to be a better way to add (at runtime) the one hundred implementations in Program.cs without explicitly spelling out all their names!

CodePudding user response：

You can use an nuget package like this or you can create an extension method and get all references of services with reflection:

public static class ServiceCollectionExtensions
{
   public static void RegisterAllTypes<T>(this IServiceCollection services, 
   Assembly[] assemblies,
    ServiceLifetime lifetime = ServiceLifetime.Transient)
   {
      var typesFromAssemblies = assemblies.SelectMany(a => 
       a.DefinedTypes.Where(x => x.GetInterfaces().Contains(typeof(T))));
      foreach (var type in typesFromAssemblies)
        services.Add(new ServiceDescriptor(typeof(T), type, lifetime));
   }
 }

and than call it at startup.cs

public void ConfigureServices(IServiceCollection services)
{
    // ....

    services.RegisterAllTypes<IInvoicingService>(new[] { typeof(Startup).Assembly });
}

But be careful , you are registering services in a collection. There is a long version of answer here. You should check.

CodePudding user response：

You can use scrutor which does assembly scanning (which it seems like what you want) https://andrewlock.net/using-scrutor-to-automatically-register-your-services-with-the-asp-net-core-di-container/

CodePudding user response：

The answer of @nzrytmn totally worked. Thank you very much!

I just made a few tweaks in RegisterAllTypes to fulfill my own requirements:

public static void RegisterAllTypes<T>(this IServiceCollection services)
{
   var assemblies = new[] { Assembly.GetEntryAssembly() };

   var typesFromAssemblies = assemblies.SelectMany(a => a?.DefinedTypes.Where(x => x.GetInterfaces().Contains(typeof(T))));
   
   foreach (var type in typesFromAssemblies)
      services.Add(new ServiceDescriptor(typeof(T), type, ServiceLifetime.Singleton));
}

Then in Program.cs:

builder.Services.RegisterAllTypes<IHostedService>();