Does .net core dependency injection support Lazy

Question

I am trying to use the generic Lazy class to instantiate a costly class with .net core dependency injection extension. I have registered the IRepo type, but I\'m not sure wh

Answer 1

Here's another approach which supports generic registration of Lazy<T> so that any type can be resolved lazily.

services.AddTransient(typeof(Lazy<>), typeof(Lazier<>));

internal class Lazier<T> : Lazy<T> where T : class
{
    public Lazier(IServiceProvider provider)
        : base(() => provider.GetRequiredService<T>())
    {
    }
}

Answer 2

You only need to add a registration for a factory method that creates the Lazy<IRepo> object.

public void ConfigureService(IServiceCollection services)
{
    services.AddTransient<IRepo, Repo>();
    services.AddTransient<Lazy<IRepo>>(provider => new Lazy<IRepo>(provider.GetService<IRepo>));
}

Answer 3

Services that are to be fetched in Lazy will be re-introduced by the factory registration method with the new Lazy of the intended service type and provided for its implementation using serviceProvider.GetRequiredService.

services.AddTransient<IRepo, Repo>()
        .AddTransient(serviceProvider => new Lazy<IRepo>(() => serviceProvider.GetRequiredService<IRepo>()));

Answer 4

To my opinion, the code below should do the work(.net core 3.1)

services.AddTransient<IRepo, Repo>();
services.AddTransient(typeof(Lazy<>), typeof(Lazy<>));