public class NullResult
    {
        public bool Resulst
        { get; set; }

        public string Message
        { get; set; }
    }

class MailConfig
{
       public string MailFrom { get; set; }
       
        public string MailTo { get; set; }

        public string MailSubject { get; set; }
      
        public string MailBody { get; set; }

        public bool IsHtml { get; set; }
     
    public NullResult ParmCheck(Expression<Func<MailConfig, string>> exp)
        {
            MemberExpression memberExp = exp.Body as MemberExpression;
            string name = memberExp.Member.Name;
            string temp = exp.Compile().Invoke(this);
            if (string.IsNullOrEmpty(temp))
            {
                return new NullResult() { Resulst = false, Message = name + " is empty" };
            }
            return new NullResult() { Resulst = true };
            
        }

        public void Check()
        {

            List<NullResult> list = new List<NullResult>() { ParmCheck(it => it.MailFrom),ParmCheck(it=>it.MailTo),ParmCheck(it=>it.MailSubject), ParmCheck(it => it.MailBody) };
            var query = list.Where(it => !it.Resulst);
            if (query.Count() > 0)
            {
                throw new ArgumentException(string.Join(",",query.Select(it=>it.Message).ToArray()));
            }
            bool _isHtml = false;
            bool.TryParse(settings["IsHtml"], out _isHtml);
            IsHtml = _isHtml;
        }
     
     
    }

ParmCheck 的方法可以允许我们的代码编写人员直接用lambda表达式的方式来过量行验证了。

ParmCheck(it => it.MailFrom);如果这个属性通不过验证。它就会直接报出这个这个属性通不过的消息了。

这样的好处是在我们如果重构了MailForm属性的时候 我们不需要去更改 字符串的信息