example15.cs

public sealed class PropertiesMustMatchAttribute : ValidationAttribute
    {
        private const string _defaultErrorMessage = "'{0}' and '{1}' do not match.";
        private readonly object _typeId = new object();
 
        public PropertiesMustMatchAttribute(string originalProperty, string confirmProperty)
            : base(_defaultErrorMessage)
        {
            OriginalProperty = originalProperty;
            ConfirmProperty = confirmProperty;
        }
 
        public string ConfirmProperty { get; private set; }
        public string OriginalProperty { get; private set; }
 
        public override object TypeId
        {
            get
            {
                return _typeId;
            }
        }
 
        public override string FormatErrorMessage(string name)
        {
            return String.Format(CultureInfo.CurrentUICulture, ErrorMessageString,
                OriginalProperty, ConfirmProperty);
        }
 
        public override bool IsValid(object value)
        {
            PropertyDescriptorCollection properties = TypeDescriptor.GetProperties(value);
            object originalValue = properties.Find(OriginalProperty, true /* ignoreCase */).GetValue(value);
            object confirmValue = properties.Find(ConfirmProperty, true /* ignoreCase */).GetValue(value);
            return Object.Equals(originalValue, confirmValue);
        }
    }