DateTimeAttribute allows you to validate a string property on a DTO as if it was a date

DateTimeAttribute.cs

    using System;
    using System.Collections.Generic;
    using System.ComponentModel.DataAnnotations;
    using System.Web.Mvc;

    [AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
    public sealed class DateAttribute : DataTypeAttribute, IClientValidatable
    {
        public DateAttribute() : base(DataType.DateTime)
        {
            ErrorMessage = "The {0} field is not a valid date.";
        }

        public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
        {
            yield return new ModelClientValidationRule
            {
                ValidationType = "date",
                ErrorMessage = FormatErrorMessage(metadata.GetDisplayName())
            };
        }

        public override bool IsValid(object value)
        {
            if (value == null)
            {
                return true;
            }

            DateTime valueAsDate;
            string valueAsString = value as string;
            return valueAsString != null && DateTime.TryParse(valueAsString, out valueAsDate);
        }
    }