Batch-Register Open-Generic Types with Simple Injector

Question

I am using Simple Injector because it is really easy to assign a bunch of generic interfaces to their concretions. I have run into a roadblock though when my generics are two levels deep. I was hoping that there is a simple solution to this I haven't thought of. Here is an example of manually hooking up a single dependency:

container
    .Register<ICommandHandler<UpdateCommand<Schools>>, UpdateCommandHandler<Schools>>();

This is what I would like to do instead:

container.Register(typeof(ICommandHandler<UpdateCommand<>>), modelAssembly);

but that does not compile.

Answer 1

the Register Auto-Registration API skips open-generic implementations, such as UpdateCommandHandler<T>, because these types typically need special handling. Instead, Register will only select non-generic implementations.

To register this open-generic implementation, you will have to register it explicitly:

container.Register(typeof(ICommandHandler<>), typeof(UpdateCommandHandler<>));

Alternatively, in case you have many open-generic implementations that can be registered in any particular order, you can Auto-Register all non-generic and open-generic implementations (excluding decorators) as follows:

var handlerTypes =
    container.GetTypesToRegister(typeof(ICommandHandler<>), new[] { modelAssembly },
        new TypesToRegisterOptions { IncludeGenericTypeDefinitions = true });

container.Register(typeof(ICommandHandler<>), handlerTypes);