/// <summary>
/// Test if a file exists in the application local cache folder.
/// </summary>
/// <param name="knownFolderId">The well known folder ID to use</param>
/// <param name="fileName">Relative name of the file to open. Can contains subfolders.</param>
/// <returns>True if file exists.</returns>
public static Task <bool> IsKnownFolderFileExistsAsync(
KnownFolderId knownFolderId,
string fileName)
{
StorageFolder workingFolder = StorageFileHelper.GetFolderFromKnownFolderId(knownFolderId);
return(workingFolder.IsFileExistsAsync(fileName));
}
/// <summary>
/// Return a stream to a specified file from the application local cache folder.
/// </summary>
/// <param name="knownFolderId">The well known folder ID to use</param>
/// <param name="fileName">Relative name of the file to open. Can contains subfolders.</param>
/// <param name="accessMode">File access mode. Default is read.</param>
/// <returns>File stream</returns>
public static Task <IRandomAccessStream> GetKnowFoldersFileStreamAsync(
KnownFolderId knownFolderId,
string fileName,
FileAccessMode accessMode = FileAccessMode.Read)
{
StorageFolder workingFolder = StorageFileHelper.GetFolderFromKnownFolderId(knownFolderId);
return(GetFileStreamAsync(fileName, accessMode, workingFolder));
}
/// <summary>
/// Gets an array of bytes from a <see cref="StorageFile"/> located in the given <see cref="StorageFolder"/>.
/// </summary>
/// <param name="fileLocation">
/// The <see cref="StorageFolder"/> to save the file in.
/// </param>
/// <param name="fileName">
/// The relative <see cref="string"/> file path.
/// </param>
/// <returns>
/// Returns the stored <see cref="byte"/> array.
/// </returns>
/// <exception cref="ArgumentNullException">
/// Exception thrown if the <paramref name="fileName"/> is null or empty.
/// </exception>
public static async Task <byte[]> ReadBytesFromFileAsync(
this StorageFolder fileLocation,
string fileName)
{
if (string.IsNullOrWhiteSpace(fileName))
{
throw new ArgumentNullException(nameof(fileName));
}
var file = await fileLocation.GetFileAsync(fileName);
return(await StorageFileHelper.ReadBytesAsync(file));
}
/// <summary>
/// Save object inside file.
/// There is no limitation to use this method (refers to <see cref="Save{T}(string, T)"/> method for simple objects).
/// </summary>
/// <typeparam name="T">Type of object saved</typeparam>
/// <param name="filePath">Path to the file that will contain the object</param>
/// <param name="value">Object to save</param>
/// <returns>When this method completes, it returns the <see cref="StorageFile"/> where the object was saved</returns>
public Task <StorageFile> SaveFileAsync <T>(string filePath, T value)
{
return(StorageFileHelper.WriteTextToFileAsync(Folder, JsonConvert.SerializeObject(value), filePath, CreationCollisionOption.ReplaceExisting));
}
/// <summary>
/// Retrieve object from file.
/// </summary>
/// <typeparam name="T">Type of object retrieved</typeparam>
/// <param name="filePath">Path to the file that contains the object</param>
/// <param name="default">Default value of the object</param>
/// <returns>Waiting task until completion with the object in the file</returns>
public async Task <T> ReadFileAsync <T>(string filePath, T @default = default(T))
{
string value = await StorageFileHelper.ReadTextFromFileAsync(Folder, filePath);
return((value != null) ? JsonConvert.DeserializeObject <T>(value) : @default);
}
