Injecting classes that inherit from a generic one in Autofac

Lets say we have a generic class defined like :

public class Foundation<TClass>  where TClass : class
{
    private readonly InjectedClass _injectedClass;

    protected Foundation(InjectedClass injectedClass)
    {
        _injectedClass = injectedClass;
    }
}

Autofac has a method : RegisterGeneric() we can use in order to register generic classes.

Usage :

builder.RegisterGeneric(typeof(Foundation<>)).InstancePerLifetimeScope();

This works perfectly but what about the classes that inherit from this generic class? For example:

public class CustomFoundation<TClass> : Foundation<TClass> where TClass :class
{
    public CustomFoundation(InjectedClass injectedClass) : base(injectedClass)
    {

    }
}

Using “RegisterGeneric()” wont work.

There are few ways to solve this problem :

1.

 builder.RegisterAssemblyTypes(typeof(Foundation<>).Assembly)
             .Where(t => t.BaseType!= null && t.BaseType.IsGenericType 
             && t.BaseType.GetGenericTypeDefinition() == typeof(Foundation<>)));

RegisterAssemblyTypes registers all components that are defined within the assembly of the Foundation class. Here we are registering all the components whose basetype is generic and is type of Foundation. 2.

 builder.RegisterAssemblyTypes(typeof(Foundation<>).Assembly)
             .AsClosedTypesOf(typeof(Foundation<>));

”“According to the api doc of Autofac: The AsClosedTypesOf specifies that a type from a scanned assembly is registered if it implements an interface that closes the provided open generic interface type.“”

3.

builder.RegisterAssemblyTypes(typeof(Foundation<>).Assembly)
    .Where(t => t.Name.EndsWith("Foundation"));

Same logic as the first step but this requires that we have a naming strategy in place and name all the derived class with the ending string “Foundation” such as “ExampleFoundation”, “TestFoundation” etc.