StorageFolder GetFolderFromPathAsync 抛出 Value does not fall in the expected range 错误

Question

我正在尝试打开一个 FileSaveDialog，当用户按下保存时，我正在 LocalFolder 中创建一个 zip 并将其移动到用户选择的位置。使用此代码，文件成功移动到所选位置，但是当我说 var storageFolder = await StorageFolder.GetFolderFromPathAsync(localfile.Path); 时出现类似 'Value does not fall within the expected range error.' 的异常请帮助。

这是完整的代码。

public async Task<bool> WriteFilesToFolder(string baseFolderName, Dictionary<string, string> contentOfFilesWithFileNames)
        {
            try
            {
                var savePicker = new FileSavePicker();
                savePicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary;

                // Dropdown of file types the user can save the file as
                savePicker.FileTypeChoices.Add("zip", new List<string>() { ".zip" });
                // Default file name if the user does not type one in or select a file to replace
                savePicker.SuggestedFileName = baseFolderName;

                StorageFile localfile = await savePicker.PickSaveFileAsync();
                if (localfile == null)
                {
                    return false;
                }

                string pathOfZip = string.Empty;
                StorageFolder destinationfolder = await ApplicationData.Current.LocalFolder.CreateFolderAsync(baseFolderName, CreationCollisionOption.ReplaceExisting);
                if (destinationfolder != null)
                {
                    StorageApplicationPermissions.FutureAccessList.AddOrReplace("PickedFolderToken", destinationfolder);

                    for (int i = 0; i < contentOfFilesWithFileNames.Count; i++)
                    {
                        var item = contentOfFilesWithFileNames.ElementAt(i);
                        string fileNameToCreate = item.Key;
                        string formattedFileName = fileNameToCreate.Replace(",", string.Empty).Replace("/", "-").Replace(":", "-");
                        var file = await destinationfolder.CreateFileAsync(string.Format("{0}.html", formattedFileName), CreationCollisionOption.ReplaceExisting);
                        var res = await WriteStorageFileAction(file, item.Value);
                    }

                    await Task.Run(() =>
                    {
                        string temp = Directory.GetParent(destinationfolder.Path).FullName;
                        pathOfZip = string.Format("{0}\{1}{2}.zip", temp, baseFolderName, DateTime.Now.ToString("yyyy-MM-dd_hh-mm"));
                        if (File.Exists(pathOfZip))
                        {
                            File.Delete(pathOfZip);
                        }

                        // Zipping file into the same folder throws exception that its being used by an other process.
                        // So zip to new location.
                        ZipFile.CreateFromDirectory(destinationfolder.Path, pathOfZip,
                                CompressionLevel.Optimal, true);
                    });

                    if (localfile != null)
                    {
                        string faToken = StorageApplicationPermissions.FutureAccessList.Add(localfile);
                        StorageFile file = await StorageFile.GetFileFromPathAsync(pathOfZip);
                        var storageFolder = await StorageFolder.GetFolderFromPathAsync(localfile.Path); //This line throws the exception.
                        await file.MoveAsync(storageFolder);
                    }

                    await destinationfolder.DeleteAsync();
                    return true;
                }
            }
            catch (Exception ex)
            {
                throw;
            }

            return false;
        }

更新：

这是 Mainifest 命名空间：

<包

xmlns="http://schemas.microsoft.com/appx/manifest/foundation/windows10"
         xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest"
         xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10"
         xmlns:desktop4="http://schemas.microsoft.com/appx/manifest/desktop/windows10/4"
         xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
         IgnorableNamespaces="uap mp rescap">

我更新了 Package Manifest 文件，如下所示。但是我在 rescap:Capability .

下有一个绿色的涂鸦

现在报错如下：

Answer 1

如果你想使用StorageFolder.GetFolderFromPathAsync方法得到一个StorageFolder对象，那么你需要传递一个文件夹路径作为参数。 localfile 对象是您从 FileSavePicker 获得的 StorageFile 对象。 localfile.Path 表示文件的位置，而不是文件夹。这就是您出现此异常的原因。

对于你的场景，如果你想得到你选择的文件的父文件夹，我建议你使用StorageFile.GetParentAsync Method

更新：

您似乎正在选取放置在 UWP 应用默认无权访问的位置的文件。所以选择器只能让你访问单个文件而你无法访问父文件夹，因为你没有访问该文件夹的权限。

请仔细阅读 File access permissions 以更好地理解此行为。

对于这样的场景，如果你想获取放置在UWP没有访问权限的某处的父文件夹。使用路径会更好。首先，您需要在清单文件中添加 broadFileSystemAccess 功能。

像这样：

     <Package
xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
  IgnorableNamespaces="uap mp rescap">

<Capabilities>
    <rescap:Capability Name="broadFileSystemAccess" />
</Capabilities>

然后，得到localfile对象后，拆分localfile的路径，就可以得到父文件夹的路径。

现在您可以这样调用 StorageFolder.GetFolderFromPathAsync：

StorageFolder.GetFolderFromPathAsync(parentfolderpath)

StorageFolder GetFolderFromPathAsync 抛出 Value does not fall in the expected range 错误

StorageFolder GetFolderFromPathAsync throws Value does not fall within the expected range error

c#

storagefile

storagefolder

uwp