Webservice无法序列化，因为它没有无参数构造函数

Question

我有一个网络服务，我已编辑，在它没有问题的情况下工作。 但是现在我得到这个错误：无法序列化，因为它没有无参数构造函数我已经在下面发布了我的类。

public class Class
{
    public class AnsweredQ
    {
        public string Question { get; set; }
        public string Answer { get; set; }

        public AnsweredQ(string _Question, string _Answer)
        {
            Question = _Question;
            Answer = _Answer;
        }
    }
    public class UnAnsweredQ
    {
        public string Question { get; set; }
        public string[] Options { get; set; }

        public UnAnsweredQ(string _Question, string[] _Options)
        {
            Question = _Question;
            Options = _Options;
        }
    }
    public class Trial
    {
        public string User { get; set; }
        public DateTime TrialDate { get; set; }
        public bool Expired { get; set; }

        public Trial (string _User, DateTime _TrialDate, bool _Expired)
        {
            User = _User;
            TrialDate = _TrialDate;
            Expired = _Expired;
        }
    }
}

如果你能解决这个问题，请解释我做错了什么:)

Answer 1

为了能够序列化/反序列化类，序列化器需要一个无参数构造函数。 因此，您需要将无参数构造函数添加到您的类中，即：

public class AnsweredQ
    {
        public string Question { get; set; }
        public string Answer { get; set; }

       public AnsweredQ() {  }


        public AnsweredQ(string _Question, string _Answer)
        {
            Question = _Question;
            Answer = _Answer;
        }
    }
    public class UnAnsweredQ
    {


        public string Question { get; set; }
        public string[] Options { get; set; }

        public UnAnsweredQ() {}

        public UnAnsweredQ(string _Question, string[] _Options)
        {
            Question = _Question;
            Options = _Options;
        }
    }


    public class Trial
    {
        public string User { get; set; }
        public DateTime TrialDate { get; set; }
        public bool Expired { get; set; }

        public Trial ()
        {
        }

        public Trial (string _User, DateTime _TrialDate, bool _Expired)
        {
            User = _User;
            TrialDate = _TrialDate;
            Expired = _Expired;
        }
    }
}