File and Folder dialogs in .NET MAUI with CommunityToolkit

Vladislav Antonyuk

Note: This is a guest blog post by Vladislav Antonyuk, who is a senior software engineer at DataArt and a core contributor of the .NET MAUI Community Toolkit.

Interacting with files and folders is a routine task for countless applications, yet it often involves writing tedious platform-specific code.

The good news is that the new CommunityToolkit.Maui version 5.0 now contains the enhanced versions of FolderPicker and FileSaver classes which provide an easy way to select target folders and save files to the filesystem across all the .NET MAUI platforms.

FileSaver

By using FileSaver, your application can offer users a convenient dialog that allows them to choose a destination folder. With only a few lines of code, you can then save any file type, including documents, images, videos, and more.

Here’s an example of how you can use FileSaver in C#:

using var stream = new MemoryStream(Encoding.Default.GetBytes("Hello from the Community Toolkit!"));
var fileSaveResult = await FileSaver.Default.SaveAsync("sample.txt", stream, cancellationToken);
if (fileSaveResult.IsSuccessful)
{
    await Toast.Make($"File is saved: {fileSaveResult.FilePath}").Show(cancellationToken);
}
else
{
    await Toast.Make($"File is not saved, {fileSaveResult.Exception.Message}").Show(cancellationToken);
}

This code opens a filesystem dialog, that allows the user to choose the target file location, creates a new file called “sample.txt” and writes a stream with the text “Hello from the Community Toolkit!” to it. Users can also change the file name to suit their needs.

FileSaver catches all exceptions and returns the operation result. However, if you would like to handle only specific exceptions like the user cancels the operation, you can wrap code in a try/catch and call the EnsureSuccess method:

using var stream = new MemoryStream(Encoding.Default.GetBytes("Hello from the Community Toolkit!"));
try
{
    var fileSaverResult = await FileSaver.SaveAsync("initial-path", "sample.txt", stream, cancellationToken);
    fileSaverResult.EnsureSuccess();

    await Toast.Make($"File is saved: {fileSaverResult.FilePath}").Show(cancellationToken);
}
catch (Exception ex)
{
    await Toast.Make($"File is not saved, {ex.Message}").Show(cancellationToken);
}

A more complete example of using FileSaver is in my MauiPaint sample application. This is how it works on macOS:

Note: Android Developers should provide permission to work with file storage.

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

FolderPicker

FolderPicker is another powerful capability that can be found as part of CommunityToolkit.Maui which allows users to select folders in the filesystem using a UI dialog. With FolderPicker developers can easily get information about the selected folder such as its name and path.

Here’s an example of how FolderPicker can be used in C#:

var folderPickerResult = await folderPicker.PickAsync(cancellationToken);
if (folderPickerResult.IsSuccessful)
{
    await Toast.Make($"Folder picked: Name - {folderPickerResult.Folder.Name}, Path - {folderPickerResult.Folder.Path}", ToastDuration.Long).Show(cancellationToken);
}
else
{
    await Toast.Make($"Folder is not picked, {folderPickerResult.Exception.Message}").Show(cancellationToken);
}

This code prompts the user to select a folder, and the result of the operation will be stored in the “folderPickerResult” variable.

Again, it’s a good idea to wrap in a try/catch in case you prefer to use the EnsureSuccess method:

try
{
    var folderPickerResult = await FolderPicker.Default.PickAsync("initial-path", cancellationToken);
    folderPickerResult.EnsureSuccess();
    await Toast.Make($"Folder picked: Name - {folderPickerResult.Folder.Name}, Path - {folderPickerResult.Folder.Path}", ToastDuration.Long).Show(cancellationToken);
}
catch (Exception ex)
{
    await Toast.Make($"Folder is not picked, {ex.Message}").Show(cancellationToken);
}

Note: Android Developers should provide permission to work with file storage.

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Summary

FileSaver and FolderPicker are two powerful new tools that can be found as part of the CommunityToolkit.Maui library. They make it easy for developers to collaborate with the filesystem to manage the files and folders. As usual, further information about these two APIs can be found in the documentation.

If you’re a developer working with C# and .NET MAUI, give them a try today and see how they can help get better integration with the OS filesystem.

Finally, be sure to check out the full release notes for version 5.0 for even more great resources for .NET MAUI developers.

Vladislav Antonyuk Senior .NET Software Engineer

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