How to get a custom attribute from object instance in C#

Question

Let's say I have a class called Test with one property called Title with a custom attribute:

public class Test {     [DatabaseField("title")]     public string Title { get; set; } } 

And an extension method called DbField. I am wondering if getting a custom attribute from an object instance is even possible in c#.

Test t = new Test(); string fieldName = t.Title.DbField(); //fieldName will equal "title", the same name passed into the attribute above 

Can this be done?

Answer 1

Here is an approach. The extension method works, but it's not quite as easy. I create an expression and then retrieve the custom attribute.

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Linq.Expressions;  namespace ConsoleApplication1 {     public class DatabaseFieldAttribute : Attribute     {         public string Name { get; set; }          public DatabaseFieldAttribute(string name)         {             this.Name = name;         }     }      public static class MyClassExtensions     {         public static string DbField<T>(this T obj, Expression<Func<T, string>> value)         {             var memberExpression = value.Body as MemberExpression;             var attr = memberExpression.Member.GetCustomAttributes(typeof(DatabaseFieldAttribute), true);             return ((DatabaseFieldAttribute)attr[0]).Name;         }     }      class Program     {         static void Main(string[] args)         {             var p = new Program();             Console.WriteLine("DbField = '{0}'", p.DbField(v => v.Title));          }         [DatabaseField("title")]         public string Title { get; set; }      } }