Cast To Interface

Question

I am not getting any errors in my code, but my filter object is always null. When I run the debugger the filter object looks just like the sort object, a list with stuff in it.

Answer 1

The list is null because you are trying to cast List<IFilterDescriptor> into List<FilterDescriptor>, but just because FilterDescriptor inherits from IFilterDescriptor doesn't mean that List<FilterDescriptor> inherits from List<IFilterDescriptor> (unless the list is covariant List<in T> which it isn't).

You should do it like this:

IList<IFilterDescriptor> filter = request.Filters;

if the interface is fine with that, otherwise you can case the list like that:

List<FilterDescriptor> filter = request.Filters.OfType<FilterDescriptor>.ToList();

Answer 2

Thanks for the help guys I talked to a friend of mine and he suggested I do this... So I guess I should not have been trying to cast the Lists and Interfaces.

    if(request.Sorts.Count == 1)
    {
        pRequest.SortMember = request.Sorts[0].Member;
        pRequest.SortDirection = (int)request.Sorts[0].SortDirection;
    }

    if (request.Filters.Count >= 1)
    {
        foreach(var item in request.Filters)
        {
            if(item is Kendo.Mvc.FilterDescriptor)
            {
                 var descriptor = (Kendo.Mvc.FilterDescriptor)item;
                 pRequest.Startdate = (DateTime)descriptor.ConvertedValue;
            }
        }                
    }
    else
    {
         var endDate = new TimeSpan(4000, 0, 0, 0, 0);
         pRequest.Startdate = DateTime.UtcNow - endDate;
    }