捕獲Entity framework驗證異常

Entity framework在驗證未通過的時候預設不會拋出詳細異常，這給我們debug帶來很大的困難，不過我們可以手動捕獲，見代碼：

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;        }