Test if class inherits generic interface

Question

I know there are a few questions on this already but I can't seem to get this to work.

I have a class like this;

public class TopLocation<T> : ILocation
{
    public string name { get; set; }
    public string address { get; set; }
}

When I create the class I specify whether it's an IRestaurant or IClub. No problem so far.

However, how do I test to see whether it's an IClub or IRestaurant in an if statement?

This fails;

if (item.trendItem is ILocation<ITopRestaurant>)

and this returns null

               Type myInterfaceType = item.trendItem.GetType().GetInterface(
                   typeof(ITopRestaurant).Name);

The reason I'd like this in an if statement is because it's sitting within an ascx page in an MVC application and I am trying to render the correct partial view.

edit

in response to the comment;

public interface ITopClub{}
public interface ITopRestaurant { }
public interface ILocation{}

Is there a generic `ILocation` as well? What's the hierarchy? What is `ITopRestaurant`? — Jon, Dec 16 '11 at 02:34
ITopRestaunt is simply an empty interface used to identify the type of ILocation this item is — griegs, Dec 16 '11 at 02:35
Possible duplicate of http://stackoverflow.com/questions/503263/how-to-determine-if-a-type-implements-a-specific-generic-interface-type — moribvndvs, Dec 16 '11 at 02:36
@HackedByChinese, saw that one but looks a little complex for what I thought should be a fairly straight forward thing to do kwim? — griegs, Dec 16 '11 at 02:37

score 2 · Accepted Answer · answered Dec 16 '11 at 02:46

2

You can simply do this:

if (item.trendItem is TopLocation<IRestaurant>)

answered Dec 16 '11 at 02:46

Erik Funkenbusch

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score 1 · Answer 2 · answered Dec 16 '11 at 02:35

First of all, ILocation is not a Generic Interface so trying to test anything against ILocation<T> is going to fail. Your class is the Generic Type.

Second, you're trying to figure out if the type used as a generic argument to your Generic Type is a given interface. To do that, you need to get the Generic Type Arguments for the type and then perform the check against that type:

var myInterfaceType = item.trendItem.GetType().GetGenericTypeArguments()[0];

if(myInterfaceType == typeof(ITopRestaurant))
{

}

Test if class inherits generic interface

2 Answers2