Accessing RequestContext in WebAPI Controller Constructor

I am trying to access the RequestContext in the constructor of my WebAPI Controller.  I have created a base WebAPI Controller from which all of my other WebAPI Controllers derive.

I tried originally accessing the Request.Headers properties directly, but these values always came up as null.

Therefore, I ended up doing this instead:

public BaseApiController()
        {
            IEnumerable<string> headerValues = new List<string>();

            Debug.WriteLine(_userNameHeader);
            
            if (System.Web.HttpContext.Current.Request.Headers.Get(_userNameHeader) != null)
            {
                //Check if the header values exists as part of the Request
                headerValues = System.Web.HttpContext.Current.Request.Headers.GetValues(_userNameHeader);

                //The username should be the 1st (and only) element in the header
                _userName = headerValues.FirstOrDefault();

            }//if
        }

However, I would like to use Ninject to use the appropriate HttpControllerContext to inject this into the constructor so that I can easily Unit Test my Web API Controllers using Moq.

The current way I have this set up does not allow me to Unit Test any of my Controllers because I end up getting a null object reference.

Please advise as to how to resolve this issue.

Thanks.