File Dialogs

The file dialog functionality is accessed through the StorageProvider API, which is available from the MainWindow. The following are two methods that demonstrate how to utilize this API for file operations.

info

For a complete, runnable example of these concepts in action, check out the sample application.

OpenFilePickerAsync

This private method opens a file picker dialog, allowing the user to select a file. This method is asynchronous and returns a Task<IStorageFile?>.

private async Task<IStorageFile?> DoOpenFilePickerAsync()
{
    if (Application.Current?.ApplicationLifetime is not IClassicDesktopStyleApplicationLifetime desktop ||
        desktop.MainWindow?.StorageProvider is not { } provider)
        throw new NullReferenceException("Missing StorageProvider instance.");

    var files = await provider.OpenFilePickerAsync(new FilePickerOpenOptions()
    {
        Title = "Open Text File",
        AllowMultiple = false
    });

    return files?.Count >= 1 ? files[0] : null;
}

Usage

This method is used to open a file picker dialog with the title "Open Text File". Only a single file can be selected at a time. If a file is selected, it is returned; otherwise, null is returned.

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SaveFilePickerAsync

This private method opens a file picker dialog, allowing the user to save a file. This method is asynchronous and returns a Task<IStorageFile?>.

Example

private async Task<IStorageFile?> DoSaveFilePickerAsync()
{
    if (Application.Current?.ApplicationLifetime is not IClassicDesktopStyleApplicationLifetime desktop ||
        desktop.MainWindow?.StorageProvider is not { } provider)
        throw new NullReferenceException("Missing StorageProvider instance.");

    return await provider.SaveFilePickerAsync(new FilePickerSaveOptions()
    {
        Title = "Save Text File"
    });
}

Usage

This method is used to open a save file dialog with the title "Save Text File". The selected file location is returned, or null if no location is selected.

note

The provided examples directly access the StorageProvider API inside the ViewModel for learning purposes. In a real-world application, it's recommended to adhere to MVVM principles by creating service classes and locating them with Dependency Injection / Inversion of Control (DI/IoC). Please refer to the IoCFileOps and DepInject projects for samples of how to achieve this.