How to handle prepopulated database in Windows Phone 8.1

Question

I need to use a prepopulated database in my Xamarin.Forms application, so I searched for possible solutions.

I've found this article and tested with Android - it worked okay.

However, it uses Windows Phone 8 - that is not compatible with Windows 8.1.

So I tried to modify this Windows Phone 8 code:

public static void CopyDatabaseIfNotExists(string dbPath)
{
  var storageFile = IsolatedStorageFile.GetUserStoreForApplication();

  if (!storageFile.FileExists(dbPath))
  {
    using (var resourceStream = Application.GetResourceStream(new Uri("people.db3", UriKind.Relative)).Stream)
    {
      using (var fileStream = storageFile.CreateFile(dbPath))
      {
        byte[] readBuffer = new byte[4096];
        int bytes = -1;

        while ((bytes = resourceStream.Read(readBuffer, 0, readBuffer.Length)) > 0)
        {
          fileStream.Write(readBuffer, 0, bytes);
        }
      }
    }
  }
}

Into this code:

public static async void CopyDatabaseIfNotExists(string dbPath)
{
  IStorageFolder applicationFolder = ApplicationData.Current.LocalFolder;

  StorageFile existingFile = await Windows.Storage.StorageFile.GetFileFromPathAsync("prep.db");
  IStorageFile storageFile = await applicationFolder.GetFileAsync(dbPath);

  if (storageFile == null)
  {
    await existingFile.CopyAndReplaceAsync(storageFile);

However, it does not work, I can't provide a proper filepath for my existing db file (it is in the root of the project), it always gives me this error:

Value does not fall within the expected range.

How could I get a proper path to my prepopulated file?

Also, why do I need to use a stream based "copy" when I could simply copy the file itself?

Answer 1

The following code works for Windows Phone 8.1 and UWP:

public async void CopyDatabaseIfNotExists(string dbPath)
{
  IStorageFolder applicationFolder = ApplicationData.Current.LocalFolder;
  var existingFile = await Windows.ApplicationModel.Package.Current.InstalledLocation.GetFileAsync(myDBFileName);

  if (!await CheckForExistingFile(myDBFileName))
    await existingFile.CopyAsync(applicationFolder);
}

private async Task<bool> CheckForExistingFile(string filePath)
{
  try
  {
    var file = await ApplicationData.Current.LocalFolder.GetFileAsync(Uri.EscapeDataString(filePath));
    //no exception means file exists
    return true;
  }
  catch (FileNotFoundException ex)
  {
    //find out through exception
    return false;
  }
}