捕获Entity framework验证错误

Entity framework在验证未通过的时候默认不会抛出详细异常，这给我们debug带来很大的困难，不过我们可以手动捕获，见代码：

private int Update(Employee entity)        {            string error = string.Empty;            using (NorthwindEntities ctx = new NorthwindEntities())            {                try                {                    //ctx.Employees.Attach(entity);                    ctx.Entry(entity).State = System.Data.EntityState.Modified;                    return ctx.SaveChanges();                }                catch (DbEntityValidationException ex)                {                    foreach (var item in ex.EntityValidationErrors)                    {                        foreach (var item2 in item.ValidationErrors)                        {                            error = string.Format("{0}:{1}\r\n", item2.PropertyName, item2.ErrorMessage);                        }                    }                }            }            return 1;        }