MotivoBajaAttribute.cs

using sage.addons.amortiza.Negocio.Mantes;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Text;

namespace sage.addons.amortiza.Negocio.Validations
{
    internal class MotivoBajaRequiredAttribute 
        : RequiredAttribute
    {
        protected override ValidationResult IsValid(object value, ValidationContext validationContext)
        {
            Partidas loPartidas = validationContext.ObjectInstance as Partidas;
           
            if(loPartidas._Fecha_Baja_Amortizacion is DateTime)
            {
                return base.IsValid(value, validationContext);
            }

            return ValidationResult.Success;

        }
    }
}