‘ServiceCollection’ does not contain a definition for ‘AddSingleton’

I’ve been registering my dependencies to my IOC container via the program class, but it got messy. I decided to write a DI provider which provided and registered dependencies inside of it.

Before I begin explaining with code, here is the full compilation error VS gives.

‘ServiceCollection’ does not contain a definition for ‘AddSingleton’
Cannot resolve symbol ‘AddSingleton’

I tried to be as clean as possible, inherting ServiceCollection class inside DependencyProvider

public class DependencyProvider : ServiceCollection, IDependencyProvider
{
    public DependencyProvider() : base()
    {
        Register();
    }

    public void Register()
    {
        base.AddSingleton<IContext, Context>(); // this line errors
        new ServiceCollection().AddSingleton<IContext, Context>(); // this line works
    }
}

Here is the IDependencyProvider interface

public interface IDependencyProvider : IServiceCollection
{
    void Register();
}

Can I not do this, or am I just doing something wrong? I really hope its possible, as the solution seems super clean, apose to creating a new instance of ServiceCollection and using the field for it.

Just to clarify the error, I can’t access any of the base methods on ServiceCollection, like so

base.AddSingleton<IContext, Context>();

But this line works, when making a new instance inline

new ServiceCollection().AddSingleton<IContext, Context>();

Answers:

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Method 1

The base keyword does not resolve extension methods. What you want to do is:

this.AddSingleton<IContext, Context>();

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