在运行时将对象转换为通用类型

Question

I'm using reflection to call a generic method, this method returns an object which I'd like to cast to call a method on after.

public static string GetTableName(this ObjectContext context, Type T)
{
    var method = typeof(ObjectContext).GetMethod("CreateObjectSet", new Type[]{});
    var generic = method.MakeGenericMethod(T);
    var objectSet = generic.Invoke(context, null);

    var sqlString = objectSet.ToTraceString(); 
    // doesn't work because ToTraceString() isn't a method of object
    // it's a method of ObjectSet<T>
    ...
}

T isn't known until runtime. How can I cast objectSet to ObjectSet<T> to be able to call ToTraceString()?

Answer 1

As TyCobb said, you have use even more reflection. Keep going until you get to some type that you can write the cast for, like string :

public static string GetTableName(this ObjectContext context, Type T)
{
    var method = typeof(ObjectContext).GetMethod("CreateObjectSet", new Type[] { });
    var generic = method.MakeGenericMethod(T);
    var objectSet = generic.Invoke(context, null);

    var toTrace = typeof(ObjectSet<>).MakeGenericType(T).GetMethod("ToTraceString");
    var sqlString = (string)toTrace.Invoke(objectSet, null);

    //...
 }