Question

If I have a host of properties in an interface, but in the example I will just use one as it demonstrates what I am trying to achieve.

  interface IFoo
  {
    [Bar()]
    string A { get; set; }
  }
 class Base { }
 class Foo : Base, IFoo
 {
   public string A { get; set; }
 }

So when I do this:

Foo f = new Foo();
f.A = "Value";
Attribute b = Attribute.GetCustomAttribute(f.GetType().GetProperty("A"), typeof(Bar));

I was expecting to be able to get the instance of my Bar attribute out. Most of this is being done in a generic class and I am using my attributes for a validation model so I can’t implicitly cast to an interface then get the attribute of the property in the interface because I never know what type the interface will be or what type will implement it. I need some way of getting the attribute out of my instance of Base for example.

public void GenericMethod<T>(T instance) where T : Base
{
    //Get my instance of Bar here.
}

I hope whatI am trying to do is clear, thanks in advance.

Answer 1

This will give you the list of all custom attributes Bar applied to all properties in type of instance:

var attibutes = instance.GetType().GetInterfaces()
                    .SelectMany(i => i.GetProperties())
                    .SelectMany(
                        propertyInfo =>
                        propertyInfo.GetCustomAttributes(typeof (BarAttribute), false)
                    );

Is that what you are looking for?