File path of Android with "content://" scheme

[tsctsc6]

I have a app that use SQLite, the file path is:

public class MyDbService
{
    public static string DatabasePath => Path.Combine(AppContext.BaseDirectory, "my.db");
    //......
}

And I did the backup function:

private async Task BackupAsync()
{
    using var file = await App.Current.TopLevel!.StorageProvider
        .SaveFilePickerAsync(new FilePickerSaveOptions
    {
        Title = "Backup",
        ShowOverwritePrompt = true,
        DefaultExtension = "db",
        SuggestedFileName = "name",
        FileTypeChoices = [new FilePickerFileType("SQLite File")
        {
            Patterns = ["*.db"],
        }]
    });
    if (file is null) return;
    using var localDbFile = await App.Current.TopLevel!.StorageProvider
        .TryGetFileFromPathAsync(MyDbService.DatabasePath);
    if (localDbFile is null) return;
    await App.Current.DbService.CloseAsync();
    await using var localStream = await localDbFile.OpenReadAsync();
    await using var backupSteam = await file.OpenWriteAsync();
    await localStream.CopyToAsync(backupSteam);
    await backupSteam.FlushAsync();
}

I found that the app works well on Windows, but not on Android.

The point is MyDbService.DatabasePath , it is /data/user/0/com.CompanyName.MyApp/files/my.db on Android, and StorageProvider.TryGetFileFromPathAsync(string) return null.

Yes, now I understand that I can't use StorageProvider.TryGetFileFromPathAsync(string) but should use StorageProvider.TryGetFileFromPathAsync(Uri) on cross platform project. However, I don't know how to convert path string to path uri, especially Android seems to need "content://" scheme uri. The database api need path string and work well on Android. How to get "content://" scheme uri of AppContext.BaseDirectory ?

[maxkatz6]

Android implementation of TryGetFileFromPathAsync(Uri) doesn't specifically require "content://" scheme.
"file://" scheme should work well until you have read permission to the path.
The same also applies to TryGetFileFromPathAsync(string) method, which only converts input string into a "file://" URI and redirects call to TryGetFileFromPathAsync(Uri).

[maxkatz6]

Also, that's important to understand, but your app does not have full access to app installation folder, not by default at least.
You shouldn't use Path.Combine(AppContext.BaseDirectory, "my.db") as a config/database path there.

Consider using Environment.GetFolderPath with LocalApplicationData.

[tsctsc6]

I try Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData) and I found it is the same with AppContext.BaseDirectory on Android.

And I try StorageProvider.TryGetFileFromPathAsync($"file://{PwdGenDbService.DatabasePath}") and still returns null.

[tsctsc6]

Considering that the database API works fine, I guess I can use the lowest-level API: FileStream .
await using var localStream = new FileStream(MyDbService.DatabasePath, FileMode.Open);
It works!