C# Reflection : Finding Attributes on a Member Field

Question

I may be asking this incorrectly, but can/how can you find fields on a class within itself... for example...

public class HtmlPart {
  public void Render() {
    //this.GetType().GetCustomAttributes(typeof(OptionalAttribute), false);
  }
}

public class HtmlForm {
  private HtmlPart _FirstPart = new HtmlPart();      
  [Optional] //<-- how do I find that?
  private HtmlPart _SecondPart = new HtmlPart();
}

Or maybe I'm just doing this incorrectly... How can I call a method and then check for attributes applied to itself?

Also, for the sake of the question - I'm just curious if it was possible to find attribute information without knowing/accessing the parent class!

Answer 1

If I understand your question correctly, I think what you are trying to do is not possible...

In the Render method, you want to get a possible attribute applied to the object. The attribute belongs to the field _SecondPart witch belongs to the class HtmlForm.

For that to work you would have to pass the calling object to the Render method:

    public class HtmlPart {
        public void Render(object obj) {
            FieldInfo[] infos = obj.GetType().GetFields(BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);

            foreach (var fi in infos)
            {
                if (fi.GetValue(obj) == this && fi.IsDefined(typeof(OptionalAttribute), true))
                    Console.WriteLine("Optional is Defined");
            }
        }
    }