OpenFileDialog.ShowDialog（）引發異常？

Question

我試圖從我的WPF視圖模型命令之一顯示一個對話框，但是當我調用ShowDialog()它拋出System.ArgumentException ，我想知道是否有人可以給我提示為什么？

這是我的代碼：

Public ReadOnly Property OpenParser As ICommand
    Get
        Return New RelayCommand(Sub(param As Object) OpenParserExecute(DirectCast(param, Frame)))
    End Get
End Property

Public Sub OpenParserExecute(ByVal mFrame As Frame)
    SaveParserExecute()
    Dim mOpenDialog As OpenFileDialog = OpenDialog
    If mOpenDialog.ShowDialog() Then ' Lines the throws the exception
        CurrentParser = New ParserEditorModel(mOpenDialog.FileName)
        mFrame.Navigate(New ParserEditor(CurrentParser))
    End If
End Sub

根據要求的StackTrace：

at MS.Internal.Interop.HRESULT.ThrowIfFailed(String message)
at MS.Internal.AppModel.ShellUtil.GetShellItemForPath(String path)
at Microsoft.Win32.FileDialog.PrepareVistaDialog(IFileDialog dialog)
at Microsoft.Win32.FileDialog.RunVistaDialog(IntPtr hwndOwner)
at Microsoft.Win32.FileDialog.RunDialog(IntPtr hwndOwner)
at Microsoft.Win32.CommonDialog.ShowDialog()
at WinTransform.GUI.MainWindowModel.OpenParserExecute(Frame mFrame) in C:\Users\Alex\Desktop\MEDLI\branches\WinTransform\GUI\ViewModels\MainWindowModel.vb:line 38

Answer 1

因為ShowDialog()本身返回Nullable(Of Boolean)並且If語句期望使用非Nullable Boolean 。

您必須將對話框的返回值轉換為Boolean ，如果為True ，則可以通過對話框的Filename屬性檢索所選文件。

例子