什么时候特定类型实际上是System.Object？

Question

In my WPF application, I have the following bit of code in an IValueConverter:

if (value.GetType().BaseType != typeof(Member))
    return string.Empty;

Member is an auto-generated Entity Framework object. When bound to a property of List<Member> it works as expected - the converter accepts this comparison and does not return.

I'm currently writing some unit tests for this part of the code. So I tested it with this:

MemberConverter conv = new MemberConverter();
Member mem = new Member{ MemberName = "Arnold" };
var result = conv.Convert((Member)mem, typeof(string), null, null);

And result comes back as String.Empty .

When I step through the code, it's the type comparison that's failing. My self-generated mem object has a BaseType of System.Object .

I can understand why the base type could come back has a plain old object. But I can't see why it's behaving differently in these two scenarios. Can someone explain, and tell me what I'm doing wrong?

Answer 1

Entity Framework is creating a dynamic type on the fly that has Member as a base type, overridding any virtual properties you supply to provide automatic 'lazy loading' magic.

You might consider doing this instead:

if (!typeof(Member).IsAssignableFrom(value.GetType()))

Or, even more directly, since you have an instance and not just a type

if (!(value is Member))