IsTrueAttrubute.cs

using System;
using System.ComponentModel.DataAnnotations;

namespace ADL.TechPubs.WebFramework.Attributes
{
    public class IsTrueAttribute : ValidationAttribute
    {
        /// <summary>
        /// Determines whether the specified value of the object is valid. 
        /// </summary>
        /// <returns>
        /// true if the specified value is valid; otherwise, false. 
        /// </returns>
        /// <param name="value">The value of the specified validation object on which the <see cref="T:System.ComponentModel.DataAnnotations.ValidationAttribute"/> is declared.</param>
        public override bool IsValid(object value)
        {
            if (value == null) return false;
            if (value.GetType() != typeof(bool)) throw new InvalidOperationException("can only be used on boolean properties.");

            return (bool)value;
        }
    }
}