Question

如何在这里解决'引用对象没有价值'..... logDTO对象具有string类型的属性。
部分财产的价值是空的。它抛出上面引用的错误。我尝试使用.ToString（）但仍然会抛出错误。

 Public Sub WriteJobLog(ByVal logDTO As JobLogDTO)
  Dim strArray As String() = {logDTO.Mode.ToString(), logDTO.UniqueId.ToString(), logDTO.ThreadId.ToString(), _
                         logDTO.StartTime.ToString(), logDTO.FinishTime.ToString(), logDTO.TimeTaken.ToString(), _
                         logDTO.PropertyId.ToString(), logDTO.ChannelId.ToString(), logDTO.URL.ToString(), _
                         logDTO.ExceptionOrResult.ToString(), logDTO.AvblWorkerThread.ToString(), logDTO.AvblPortThread.ToString(), _
                         logDTO.AcqrdWorkerThread.ToString(), logDTO.AcqurdPortThread.ToString(), logDTO.JobsToProcess.ToString()}
  Dim lLogObj As Logging = New Logging(JobType.JOB_TRANSACTTIONAL)
  lLogObj.WriteLogFile(String.Join(Configuration.LogDelimiter, strArray))
End Sub

JobLogDTO

   public class JobLogDTO
  {
    public string  Mode { get; set; }
    public string  UniqueId { get; set; }
    public string  ThreadId { get; set; }
    public string  StartTime { get; set; }
    public string  FinishTime { get; set; }
    public string  TimeTaken { get; set; }
    public string  PropertyId { get; set; }
    public string  ChannelId { get; set; }
    public string  URL { get; set; }
    public string  ExceptionOrResult { get; set; }
    public string  AvblWorkerThread { get; set; }
    public string  AvblPortThread { get; set; }
    public string  AcqrdWorkerThread { get; set; }
    public string  AcqurdPortThread { get; set; }
    public string  JobsToProcess { get; set; }
  }

更新：
logDTO对象的值

         AcqrdWorkerThread  "24"    String
        AcqurdPortThread    "24"    String
        AvblPortThread      "400"   String
        AvblWorkerThread    "399"   String
        ChannelId           Nothing String
        ExceptionOrResult   Nothing String
        FinishTime          Nothing String
        JobsToProcess      "24" String
        Mode               "Parallel"   String
        PropertyId          Nothing String
        StartTime          "04.04.2013 12:17:25"    String
        ThreadId           "5"  String
        TimeTaken          Nothing  String
        UniqueId           "97693c1b-2bbc-4e40-a542-291568aeee4c"   String
        URL                Nothing  String

Answer 1

通常.ToString()函数将任何instance的值转换为其等效的string表示。但在这里你的instance一无所获。这就是为什么它会引发异常Referenced object has value of nothing。

我建议您在案例中使用Trim()。即使传递的empty string为argument，它也只会返回nothing。

<强>实施例

trim(logDTO.Mode)

引用对象没有任何值

1 个答案: