ASP WebAPI General Optional List Parameter

Question

I really struggle with that. I need a generic list parameter for my Get method, but it should be optional. I just did this:

public dynamic Get(List <long> ManufacturerIDs = null) 

Unfortunately, at runtime I get an error message:

The optional parameter 'ManufacturerIDs' is not supported by 'FormatterParameterBinding'.

How to get a general list as an optional parameter here?

Answer 1

What is the point of using an optional parameter? List<T> is a reference type, and if the client does not specify a value, it will simply be null:

 public HttpResponseMessage Get(List<long> manufacturerIDs) { ... }