Simple method to check if a directory is empty in WinRT (async API)

Question

I wanted to create a simple IsEmpty(StorageFolder directory) method that works in WinRT apps, i.e. that uses the async API. I don't see a relevant method in the documentation for the StorageFolder class, and I also haven't found anything in my searches. I'm sorry if I've missed it!

I managed to create the following method, which works:

public static async Task<bool> IsEmpty(StorageFolder directory)
{
    var files = await directory.GetFilesAsync();
    if (files.Count > 0)
    {
        return false;
    }

    var folders = await directory.GetFoldersAsync();
    if (folders.Count > 0)
    {
        return false;
    }

    return true;
}

But... is there a cleaner way? Either native or that I could code... It should be a simple thing to check if a directory is empty, but I know I've faced problems before when simply trying to check if a directory or file exists using the async API of WinRT.

I'm also not entirely sure if the asynchronous calls to GetFilesAsync and GetFoldersAsync get every file/folder in the directory before returning, or if they can somehow only get a single item before realizing that Count will be higher than 0 (I'm thinking of lazy evaluation, like in the Haskell language, but this is C#...). If they could, I would be more at peace with this method :)

Answer 1

StorageFolder.GetItemsAsync(0,1) will retrieve the first file or sub-folder:

public static async Task<bool> IsEmpty(StorageFolder directory)
{
    var items = await directory.GetItemsAsync(0,1);
    return items.Count == 0;
}

GetFilesAsync and GetFoldersAsync will return all of the files or folders. These calls don't know that you are only going to care about the count, and I doubt the compiler is smart enough to realize that and rewrite the calls to use filtered versions automatically.