Question

我发现很多人都在询问这个错误，但我可以找到一个正确的答案并解释一下。

类：Update

 public class Log
{

    public int id { get; set; }
    public string description { get; set; }
    public string type { get; set; }
    public string action { get; set; }
    public DateTime date { get; set; }
    public string fullname { set; get; }

    public Log() {

    }
    public Log(LogDs.LogFileRow row)
    {
        this.id = row.id;
        this.type = row.type;
        this.action = row.action.ToString();
        this.description = row.description.ToString();
        this.date = row.date;
        this.fullname = row.fullname;
    }
}

Bc课程：

public class LogBC
{
    LogDalc dalc = new LogDalc();

    public List<Log> List(DateTime dateStart, DateTime dateEnd)
    {
        List<Log> listLog = new List<Log>();

        LogDs.LogFileDataTable dt = dalc.Sel(dateStart, dateEnd);

        for (int i = 0; i < dt.Count; i++)
        {
            Log exp = new Log(dt[i]);

            listLog.Add(exp);
        }

        return listLog;
    }

Dalc课程：

public class LogDalc: BaseDalc
{

    public LogDs.LogFileDataTable Sel(DateTime dateStart, DateTime dateEnd)
    {
        LogDs ds = new LogDs();

        using (SqlConnection con = new SqlConnection(Global.Config.ConnStr))
        {
            SqlCommand cmd = new SqlCommand("spp_txn_expenses_sel", con);
            cmd.CommandType = CommandType.StoredProcedure;

            cmd.Parameters.Add(new SqlParameter("@sdate", dateStart == DateTime.MinValue ? dbNull : dateStart));
            cmd.Parameters.Add(new SqlParameter("@edate", dateEnd == DateTime.MinValue ? dbNull : dateEnd));

            FillDataSet(cmd, ds, new string[] { ds.LogFile.TableName });
        }

        return ds.LogFile;
    }

}

错误显示在Bc类中，完全在Log exp = new Log(dt[i]);中。任何人都可以解释为什么会发生这种情况以及如何解决它？

Answer 1

Log类上没有构造函数接受单个参数。

提供参数化构造函数：

public class Log
{

    public int id { get; set; }
    public string description { get; set; }
    public string type { get; set; }
    public string action { get; set; }
    public DateTime date { get; set; }
    public string fullname { set; get; }

    public Log(object myValue) {
      // your logic for myValue assignment to some property
    }
}

或使用属性的内联分配

Log exp = new Log() { Description = dt[i].ToString() };

Answer 2

您的Log课程不知道如何处理您传递的参数。您需要定义一个采用这种参数的构造函数：

public Log(LogDs.LogFileDataTable dt)
{
    // initialize your settings from the DataTable here
}

不包含带1个参数的构造函数＆＃34; 4＆＃34;

2 个答案: