在事件中向父级发送值然后关闭子窗体

Question

我有一个父表单，其中包含一个从数据库填充的组合框，用户可以从中进行选择。组合框中的最后一个值是“添加新值”，如果用户选择此项，则会打开一个子表单供用户向数据库添加新值。我有一个按钮按下事件来将此值添加到数据库中，将新的return value 发送给父级并关闭表单。然后父级应该从它的组合框中选择新值并等待用户执行另一个操作。

但是，将return value 发送给父级并关闭表单的代码无法正常工作。我hide子，然后调用它与父函数访问return value。此时子窗体shows 和代码在运行另一个hide 或close 之前停止。

我该如何解决这个问题（下面的代码）？

父组合框事件：

Private Sub cmbLocations_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles cmbLocations.SelectedIndexChanged
    If Not cmbLocations.SelectedIndex = -1 Then
        If cmbLocations.SelectedIndex = cmbLocations.Items.Count - 1 Then
            If diaAddLocation.IsAccessible = False Then diaAddLocation.Activate()
            diaAddLocation.RequestSender = Me
            diaAddLocation.ShowDialog()
            FillLocations()
            cmbLocations.SelectedIndex = LocationFromLocationName(diaAddLocation.formresult)
            diaAddLocation.Close()
            diaAddLocation.Dispose()
        Else
            bttYes.Enabled = True
        End If
    End If
End Sub

子按钮按下和返回值函数

Public Sub bttAddLOCtoDatabase_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles bttAddLOCtoDatabase.Click

    Dim LocationToBeAdded As String
    LocationToBeAdded = "'" & TextBox1.Text & "'"
    AddLocation("'" & textbox1.Text & "'")
    FormResult = textbox1.Text
    GetLocations()
    frmFieldMaster.InitialiseNewParameter()
    Me.Hide()
End Sub


Public Function Result() As String
    Return FormResult
End Function

编辑：

实现了史蒂夫解决方案的代码：

Public Sub bttAddLOCtoDatabase_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles bttAddLOCtoDatabase.Click

    Dim LocationToBeAdded As String
    LocationToBeAdded = "'" & TextBox1.Text & "'"
    AddLocation("'" & textbox1.Text & "'")
    FormResult = textbox1.Text
    GetLocations()
    frmFieldMaster.InitialiseNewParameter()
    DialogResult = Windows.Forms.DialogResult.OK
    'me.Hide()

End Sub

Public Function Result() As String
    Return FormResult
    Me.Close()
End Function

Private Sub cmbLocations_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles cmbLocations.SelectedIndexChanged
    Dim ValueTaken As Boolean = False
    If Not cmbLocations.SelectedIndex = -1 Then
        If cmbLocations.SelectedIndex = cmbLocations.Items.Count - 1 Then
            Using diaaddlocation = New diaAddLocation
                diaaddlocation.requestsender = Me
                If DialogResult.OK = diaaddlocation.showdialog Then
                    FillLocations()
                    cmbLocations.SelectedIndex = LocationFromLocationName(diaaddlocation.result)
                    diaaddlocation.close()
                ElseIf DialogResult.Cancel = diaaddlocation.showdialog Then
                    cmbLocations.SelectedIndex = -1
                End If
            End Using
        Else
            bttYes.Enabled = True
        End If
    End If
End Sub

当我运行代码时，它会输入IF DialogResult.OK... 并打开孩子。然后当我关闭孩子时，父母会运行接下来的两行代码并从孩子那里得到结果。在此之后，父母再次运行IF DialogResult.OK... 并在孩子打开时停止。代码永远不会到达diaaddlocation.close 行。

Answer 1

您不需要所有这些。你可以试试这样的

   If cmbLocations.SelectedIndex = cmbLocations.Items.Count - 1 Then
        Using diaAddLocation = new diaAddLocation()
             diaAddLocation.RequestSender = Me
             if DialogResult.OK = diaAddLocation.ShowDialog() then
                 FillLocations()
                 cmbLocations.SelectedIndex = LocationFromLocationName(diaAddLocation.formresult)
             End If
        End Using
   Else
       .....

这需要将bttAddLOCtoDatabase 的DialogResult 属性设置为DialogResult.OK，并将子窗体AcceptButton 属性设置为bttAddLOCtoDatabase。现在您可以删除 bttAddLOCtoDatabase_Click 方法中的 Hide() 调用

这是有效的，因为在您不退出 Using 语句之前，您的子表单仍然可以读取其属性（结果）

编辑：与主要问题无关，但这些行是错误的：

 ElseIf DialogResult.Cancel = diaaddlocation.showdialog Then
       cmbLocations.SelectedIndex = -1

你应该去

  Using diaAddLocation = new diaAddLocation()
      diaAddLocation.RequestSender = Me
      Dim dr = diaAddLocation.ShowDialog()
      if dr = DialogResult.OK then
          ....
      else if dr = DialogResult.Cancel then
          ....
      end if

Answer 2

我不明白是什么问题，但如果你没有得到“FormResult”的价值

如果你关闭没关系，但最好在关闭它之前设置 DialogResult，因为你将它显示为对话框（showdialog）

验证 diaAddLocation 是你的窗口的实例，而不是直接的窗口类 如果您的表单名称是 frmdiaAddLocation，则不要像这样使用它

frmdiaAddLocation.showdialog

像这样使用它

Dim diaAddLocation AS  frmdiaAddLocation = New frmdiaAddLocation()
diaAddLocation.ShowDialog()

只有这样使用才能为您提供结果价值