Demo of extending EF classes and adding metadata.

Feedback.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

using System.Web.Mvc;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using DataAnnotationsExtensions;

namespace MobileAPI.Models
{
    [MetadataType(typeof(FeedbackMetadata))]
    public partial class Feedback
    {
    }

    public class FeedbackMetadata
    {
        [DisplayName("Name")]
        [PlaceHolder("Name")]
        [Required(ErrorMessage = "*")]
        public string name { get; set; }

        [Email]
        [DisplayName("Email")]
        [PlaceHolder("Email")]
        [Required(ErrorMessage = "*")]
        public string email { get; set; }

        [AllowHtml]
        [DisplayName("Comment")]
        [PlaceHolder("Comment")]
        [Required(ErrorMessage = "*")]
        public string comment { get; set; }
    }
}