Question

I am given:

• A class “T” which implements properties that are decorated with Attributes that I am interested in.

• A PropertyInfo “p” representing a property belonging to (1) an interface “I” that T implements, (2) a base class “B” that T inherits from, or (3) the class T itself.

I need to get the Attributes defined on (or inherited by) the properties in T, even if p‘s DeclaringType is an interface that T implements or a class that T inherits from. So I need a way to get from p to the PropertyInfo that actually exists on T. Thus it seems that there are 3 cases:

1. p.DeclaringType == typeof(T)

   This is the trivial case. I can iterate through T‘s properties until I find the match. Example:

   return typeof(T).GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic)
                   .FirstOrDefault(property => property == p)
   

2. p.DeclaringType == typeof(I) where I is an interface that T implements

   This is more complicated. I found that I can use an InterfaceMapping to find the corresponding implementation of the p in T. It seems kind of hackish, but here what works:

   if (p.DeclaringType.IsInterface &&
       typeof(T).GetInterfaces().Contains(p.DeclaringType))
   {
       InterfaceMapping map = typeof(T).GetInterfaceMap(p.DeclaringType);
       MethodInfo getMethod = p.GetGetMethod();
       for (int i = 0; i < map.InterfaceMethods.Length; i++)
       {
           if (map.InterfaceMethods[i] == getMethod)
           {
               MethodInfo target = map.TargetMethods[i];
               return typeof(T).GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic)
                               .FirstOrDefault(property => property.GetGetMethod() == target);
           }
       }
   }
   

3. p.DeclaringType == typeof(B) where B is a class that T inherits from

   I have not yet been able to figure out how to identify the property on T that overrides a virtual property p defined in Ts base class B.

So my questions are

• In case 3 how do I find the PropertyInfo on T that overrides the property p on B?
• Is there a better way to do all three? Perhaps a way to unify the three cases.

Answer 1

I found a way to answer case 3. The key is MethodInfo.GetBaseDefinition

if (typeof(T).IsSubclassOf(p.DeclaringType))
{
    MethodInfo baseDefinition = p.GetGetMethod().GetBaseDefinition();
    return typeof(T).GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic)
                    .FirstOrDefault(property => property.GetGetMethod().GetBaseDefinition() == baseDefinition);
}

However this only works for properties that have been overridden on T.

Edit:

By comparing the following, it doesn’t matter if the properties have or haven’t been overriden on T:

property.GetGetMethod().GetBaseDefinition().MetadataToken == baseDefinition.MetadataToken