OpenFileDialog.ShowDialog（）抛出一个异常？ [英] OpenFileDialog.ShowDialog() throws an exception?

问题描述

我想从我的WPF视图模型中的一个显示一个对话框的命令时，我称之为的ShowDialog（），它抛出一个 System.ArgumentException ，我想知道如果任何人都可以给我一个提示，为什么？

I am trying to show a dialog from one of my WPF view model commands however when i call ShowDialog() it throws a System.ArgumentException, I was wondering if anyone could give me a hint as to why?

下面是我的code：

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

堆栈跟踪的要求： 在MS.Internal.Interop.HRESULT.ThrowIfFailed（字符串消息）在MS.Internal.AppModel.ShellUtil.GetShellItemForPath（字符串路径），在Microsoft.Win32.FileDialog。prepareVistaDialog（IFileDialog对话框）在Microsoft.Win32.FileDialog .RunVistaDialog（IntPtr的hwndOwner）在Microsoft.Win32.FileDialog.RunDialog（IntPtr的hwndOwner）在Microsoft.Win32.CommonDialog.ShowDialog（）在WinTransform.GUI.MainWindowModel.OpenParserExecute（帧mFrame）在C：\用户\亚历克斯\桌面\ MEDLI \分支机构\ WinTransform \ GUI \的ViewModels \ MainWindowModel.vb：38行

StackTrace as requested: " 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"

谢谢， 亚历克斯。

推荐答案

由于的ShowDialog（）本身返回可空（布尔）和您的如果语句期待一个非空的布尔。

Because ShowDialog() itself returns a Nullable(Of Boolean) and your If statement is expecting a non-Nullable Boolean.

您将不得不在对话框的返回值转换为布尔，如果它真 retreive选定的文件通过你的对话框的文件名属性。

You'll have to cast the dialog's return value to a Boolean and if it's True retreive the selected file through your dialog's Filename property.

<一个href="http://www.vbdotnetheaven.com/UploadFile/dbeniwal321/OpenFileDialogwpf08162009233449PM/OpenFileDialogwpf.aspx"相对=nofollow>为例。

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