Set property of a custom attribute

See more:

C#

.NET

.NET4

I need to change the property of an attribute at run time.

Example:

public partial class Class1
{
  [Attr1("")]
  public string ID { get; set; }
}

public class Attr1: Attribute
{
   public string Type { get; set;}

   public Attr1() { }

   public Attr1(string type)
   {
     Type = type
   }
}

When testing:

Class1 c = new Class1();
c.ID = "ID1";
PropertyInfo propPK = c.GetType().GetProperty("ID");
object[] attrs = propPK.GetCustomAttributes(typeof(Attr1), false);
if (attrs.Length > 0)
{
  object attr = attrs.First();
  attr.GetType().GetProperty("Type").SetValue(attr, "Type1" , null);
}

So when I check the [C] object in order the check if the property of the attribute is set, I see it blank...