.net 后台工作程序未设置'e.result'`

概述：
我有几个后台工作人员用于将数据导入access数据库，然后执行一些计算。我使用

e.Argument

和

e.Result

在后台工作人员之间传递参数的

hashtable

。此哈希表包含有关要导入的文件的数据

问题：
在我的一个后台工作程序（流程中约有四分之一）上，我无法设置

e.result

，而是将其保持为

nothing

，这会导致工作程序完成的子例程出错。据我所知，这是我为其他员工编写的所有代码的副本，因此没有理由不设置此代码

代码：

Private Sub bwConditionCalc_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bwConditionCalc.DoWork
    Dim Dates As New List(Of Date)
    Dim Arguments As Hashtable
    Arguments = e.Argument

'Worker Content-----------

    Arguments("VariablesCalculated") = VariablesCalculated
    LabelString = "Tasks Complete..."
    e.Result = Arguments
End Sub

Private Sub bwConditionCalc_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles bwConditionCalc.RunWorkerCompleted
    Dim Arguments As New Hashtable
    Arguments = e.Result
    ' Check if missed calc Params can now be calculated/scaled
'The Error occurs here---------------------       
    If Not Arguments("VariablesCalculated") = 0 Then      
        Arguments("SchedCalculateData") = True
        Arguments("SchedConditionalCalc") = True
    End If
    prgFieldMaster.Value = 0
    lblStatus.Text = LabelString
    RunWorkSchedule(Arguments)
End Sub

编辑：

DeepCopy

例程返回一个哈希表，并作为一个尝试的修复程序放在那里。我仍然会在没有深度复制的情况下收到相同的错误，我将从引用的代码中删除到现在

编辑-

e.错误

句柄
私有子BWConditionalc_RunWorkerCompleted（ByVal发送方作为对象，ByVal e作为System.ComponentModel.RunWorkerCompletedEventArgs）处理BWConditionalc.RunWorkerCompleted

    If (e.Error IsNot Nothing) Then
        MessageBox.Show(e.Error.Message)
    End If
    Dim Arguments As New Hashtable
    Arguments = e.Result
    ' Check if missed calc Params can now be calculated/scaled
    If Not Arguments("VariablesCalculated") = 0 Then
        Arguments("SchedCalculateData") = True
        Arguments("SchedConditionalCalc") = True
    End If
    prgFieldMaster.Value = 0
    lblStatus.Text = LabelString
    RunWorkSchedule(Arguments)
End Sub

编辑-工作人员时间表

Private Sub bwConditionCalc_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bwConditionCalc.DoWork
    Dim Dates As New List(Of Date)
    Dim Arguments As Hashtable
    Arguments = e.Argument

'Worker Content-----------

    Arguments("VariablesCalculated") = VariablesCalculated
    LabelString = "Tasks Complete..."
    e.Result = Arguments
End Sub

Private Sub bwConditionCalc_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles bwConditionCalc.RunWorkerCompleted
    Dim Arguments As New Hashtable
    Arguments = e.Result
    ' Check if missed calc Params can now be calculated/scaled
'The Error occurs here---------------------       
    If Not Arguments("VariablesCalculated") = 0 Then      
        Arguments("SchedCalculateData") = True
        Arguments("SchedConditionalCalc") = True
    End If
    prgFieldMaster.Value = 0
    lblStatus.Text = LabelString
    RunWorkSchedule(Arguments)
End Sub

下面的子例程由创建原始参数哈希表的启动子例程调用。在每个辅助进程完成后，它会在辅助进程完成的例程中再次调用此子进程。 在导致调用此操作的例程之前的周期，我正在调用

Importchecker

，

ImportData

，

CalculateData

，然后调用

ConditionalCalc

    Public Sub RunWorkSchedule(ByVal Arguments As Hashtable)
    Me.Refresh()
    'Do nothing if worker is busy
    If bwCalcParam.IsBusy = True Or bwScaleData.IsBusy = True Or bwImportWriter.IsBusy = True Or bwColumnAdder.IsBusy = True Or bwConditionCalc.IsBusy = True Or bwDeleteParameterbyUpload.IsBusy Or bwDeletebyParameterOrCondition.IsBusy Or bwEventCalc.IsBusy Or bwImportChecker.IsBusy Or bwAddRawTables.IsBusy Then Exit Sub
    DataSchedRunning = True
    'Scheduled tasks:

    If Arguments("SchedUploadDelete") = True Then
        Arguments("SchedUploadDelete") = False
        lblStatus.Text = "Deleting Data by Upload"
        bwDeleteParameterbyUpload.RunWorkerAsync(Arguments)
        Exit Sub
    End If
    If Arguments("SchedDeletebyParameterOrCondition") = True Then
        Arguments("SchedDeletebyParameterOrCondition") = False
        lblStatus.Text = "Deleting Data by Parameter Or Condtion"
        bwDeletebyParameterOrCondition.RunWorkerAsync(Arguments)
        Exit Sub
    End If
    If Arguments("SchedAddRawTables") = True Then
        Arguments("SchedAddRawTables") = False
        lblStatus.Text = "Adding raw data tables to the Database..."
        bwAddRawTables.RunWorkerAsync(Arguments)
        Exit Sub
    End If
    If Arguments("SchedColumnAdder") = True Then
        Arguments("SchedColumnAdder") = False
        lblStatus.Text = "Adding Columns to the Database..."
        bwColumnAdder.RunWorkerAsync(Arguments)
        Exit Sub
    End If
    If Arguments("SchedImportChecker") = True Then
        Arguments("SchedImportChecker") = False
        lblStatus.Text = "Preparing to check Import Files..."
        bwImportChecker.RunWorkerAsync(Arguments)
        Exit Sub
    End If
    If Arguments("SchedImportData") = True Then
        Arguments("SchedImportData") = False
        lblStatus.Text = "Preparing to Import data..."
        bwImportWriter.RunWorkerAsync(Arguments)
        Exit Sub
    End If
    If Arguments("SchedCalculateData") = True Then
        Arguments("SchedCalculateData") = False
        lblStatus.Text = "Preparing to Calculate data..."
        bwCalcParam.RunWorkerAsync(Arguments)
        Exit Sub
    End If
    If Arguments("SchedConditionalCalc") = True Then
        Arguments("SchedConditionalCalc") = False
        lblStatus.Text = "Preparing to Calculate Conditional Data..."
        bwConditionCalc.RunWorkerAsync(Arguments)
        Exit Sub
    End If
    If Arguments("SchedScaleData") = True Then
        Arguments("SchedScaleData") = False
        lblStatus.Text = "Preparing to Scale Data..."
        bwScaleData.RunWorkerAsync(Arguments)
        Exit Sub
    End If

    If Arguments("SchedEventCalc") = True Then
        Arguments("SchedEventCalc") = False
        lblStatus.Text = "Preparing to Calculate Events"
        bwEventCalc.RunWorkerAsync(Arguments)
        Exit Sub
    End If
Finish:
    If SchedNewArgument = True Then
        timNextTask.Enabled = True
    End If
    lblStatus.Text = "Tasks Complete"
    StatusStrip1.Refresh()
    DataSchedRunning = False
End Sub

---

在此代码中，

e.Result

可以设置为

Nothing

的唯一方法是

DeepCopy

返回

Nothing

。这不是

e.Result

的问题。使用传入的参数调试

DeepCopy

方法，您将发现问题。

您忘记先检查e.Error。这是一个困难的要求，没有其他方法可以知道DoWork（）事件处理程序因异常而提前终止。好吧，除了崩溃，你会从使用结果中得到什么。使用Debug+异常调试，勾选CLR异常的抛出复选框。@HansPassant，我已打开CLR异常的抛出，但仍然没有抛出任何内容。我还添加了一个e.error检查，该检查来自上面的示例，但它也是

nothing

。我是否需要更改worker.dowork例程中的代码？非常感谢“我使用e.Argument和e.Result在后台工作人员之间传递了一个参数哈希表。”所以你要将它们链接在一起？“你能告诉我你是怎么做的吗？”懒鬼，请看上面……真是一团糟。就个人而言，我只使用一个BackgroundWorker（）并使用其ReportProgress（）方法，而不是RunWorkerCompleted（）并将其“链接”在一起。您仍然可以将代码分解成不同的方法来保持整洁。然后，在DoWork（）处理程序中只有一个“main”序列，依次调用每个步骤，然后调用ReportProgress（）。遵循流程的逻辑和流程会容易得多。我还可以让你更容易发现问题所在……请看我刚才添加的编辑。DeepCopy不会更改哈希表，只是试图进行错误后修复。如果没有它，我仍然会得到相同的错误。@pezzz，那么这意味着在

DoWork

其他地方会抛出异常。我猜，

e.Argument

是

null

因此，当您尝试在下一行访问

Arguments

时，您会得到一个

null引用异常。我想我需要检查代码的其余部分。