I cannot, for the life of me, get this data to bind. Here's my JavaScript:

var params = { 'InvItemIDs': ["188475", "188490"]};
$.post("api/Orders/OrderFromInventory?" + $.param(params))

and the Controller action:

public HttpResponseMessage OrderFromInventory(IList<int> InvItemIDs)
{
    return new HttpResponseMessage();
}

I've built the query string so that it's sending:

?InvItemIDs=188475&InvItemIDs=188490

as well as

?InvItemIDs[]=188475&InvItemIDs[]=188490

and even

?InvItemIDs[0]=188475&InvItemIDs[1]=188490

and none of them are binding. InvItemIDs is always null. What am I doing wrong?

EDIT:

So it turns out all this is a bug (or something) in the new Web API controller code in MVC4. As soon as I moved the exact same code over to a standard controller it started working.

I'm still interested if anyone has any insight as to why the Web API would break this binding.