using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public abstract class FieldNameAttribute : Attribute

    {

        public string FieldName { get; private set; }

​

        public FieldNameAttribute(string fieldName)

        {

            FieldName = fieldName;

        }

    }

    public class SomeFieldNameAttribute : FieldNameAttribute

    {

        public SomeFieldNameAttribute(string fieldName) : base(fieldName) {}

    }

    public class OtherFieldNameAttribute : FieldNameAttribute

    {

        public OtherFieldNameAttribute(string fieldName) : base(fieldName) {}

    }

    public enum FieldNames

    {

        [SomeFieldName("campo x")]

        [OtherFieldName("campo1")]

        Field1,

        [OtherFieldName("campo2")]

        Field2,

        [SomeFieldName("campo z")]

        [OtherFieldName("campo3")]

        Field3,

        [SomeFieldName("campo a")]

        Field4,

    }

    public static class FieldNameHelper

    {

        public static List<string> GetAllFieldNames<TEnum, TAttribute>()

            where TEnum : Enum

            where TAttribute : FieldNameAttribute

        {

            var fields = new List<string>();

            foreach (TEnum t in Enum.GetValues(typeof(TEnum)))

            {

                var fieldName = t.GetFieldName<TAttribute>();

                if (!string.IsNullOrEmpty(fieldName)) { fields.Add(fieldName); }

            }

            return fields;

        }

    }

    public static void Main()

    {

        Console.WriteLine($"{nameof(SomeFieldNameAttribute)} field names:");

        FieldNameHelper.GetAllFieldNames<FieldNames, SomeFieldNameAttribute>().ForEach(x => Console.WriteLine(x));

        Console.WriteLine($"\n{nameof(OtherFieldNameAttribute)} field names:");

        FieldNameHelper.GetAllFieldNames<FieldNames, OtherFieldNameAttribute>().ForEach(x => Console.WriteLine(x));

    }

}

​

public static class FieldNameExtensions

{

    public static string GetFieldName<TAttribute>(this Enum value)

        where TAttribute : Program.FieldNameAttribute

    {

        var attr = value

            .GetType()

            .GetField(value.ToString())

            .GetCustomAttributes(typeof(TAttribute), false)

            .FirstOrDefault() as TAttribute;

        return attr != null ? attr.FieldName : string.Empty;

​

    }

}