Is there a robust way to register dependencies in ASP.NET Core 3.1 beside adding everything into Startup class?

John :

I have an ASP.NET Core 3.1 project. Typically, I register any dependency using the ConfigureServices() method in the Startup.cs class.

But, I find myself having to register lots of dependencies and the ConfigureServices() looks huge! I know I can probably create an extension method of a static method and call it from the ConfigureService()` class, but wondering if there is a better way.

If there a way to register dependencies in the IoC container without having to define them one at a time like this

services.AddScoped<Interface, Class>();
.... 200 lines later
services.AddScoped<ISettings, Settings>()

poke :

Grouping related dependencies into custom extension methods is a very common way to do this. ASP.NET Core already does this for many of the internal services, and you can easily expand on top of that and set them up the way you need for your application. For example to set up authentication and authorization:

public IServiceCollection AddSecurity(this IServiceCollection services)
{
    services.AddAuthentication()
        .AddCookie();

    service.AddAuthorization(options =>
    {
        options.DefaultPolicy = …;
    });

    return services;
}

You can do the same for your application-specific services and group them logically in separate extension methods.

If you have a lot of service registrations that are very similar, you can also employ a convention-based registration e.g. using Scrutor. For example, this registers all services within a certain namespace as transient for their respective interface:

services.Scan(scan => scan
    .FromAssemblyOf<Startup>()
        .AddClasses(c => c.InNamespaces("MyApp.Services"))
            .AsImplementedInterfaces()
            .WithTransientLifetime()
);

Scrutor allows for very complex rules to scan for services, so if your services do follow some pattern, you will likely be able to come up with a rule for that.