FolderEnumeration

topic	languages	products
sample	csharp cpp cppcx cppwinrt js	windows windows-uwp

Folder enumeration sample

Shows how to enumerate the top-level files and folders inside a location (like a folder, device, or network location), and how to use queries to enumerate all files inside a location by sorting them into file groups.

Note: This sample is part of a large collection of UWP feature samples. If you are unfamiliar with Git and GitHub, you can download the entire collection as a ZIP file, but be sure to unzip everything to access shared dependencies. For more info on working with the ZIP file, the samples collection, and GitHub, see Get the UWP samples from GitHub. For more samples, see the Samples portal on the Windows Dev Center.

This sample uses Windows.Storage and Windows.Storage.Search APIs, including StorageFolder and StorageFolderQueryResult.

The sample demonstrates these tasks:

1. Enumerate top-level files and subfolders of a folder

   Uses the StorageFolder.GetFilesAsync and StorageFolder.GetFoldersAsync methods to enumerate only the top-level files and folders (the immediate children) of the location (in this case, the Pictures library). For a walkthrough of this task, see Quickstart: Accessing files programmatically.

2. Query all the files in a folder (and its subfolders) and create groups of files to enumerate

   Uses the StorageFolder.CreateFolderQueryWithOptions method to sort all files in the location (in this case, the Pictures library) into groups based on the criteria that you specify and uses a StorageFolderQueryResult.GetFoldersAsync method to retrieve the resulting file groups.

   File groups are virtual folders that are represented by StorageFolder objects. The files in a file group have the criteria that you specify in common. For example, as the sample shows, the files in a group might have the same rating.

   For a walkthrough of this task, see Quickstart: Accessing files programmatically.

3. Query all the files in a folder (and its subfolders) and retrieve file properties as a part of getting results for the query

   Uses QueryOptions.SetPropertyPrefetch to specify properties to retrieve when the query is created. StorageFolder.CreateFolderQueryWithOptions and GetFilesAsync are used to create the query and enumerate results. Similarly, you can use SetThumbnailPrefetch to retrieve thumbnails as a part of creating the query.

   Using SetPropertyPrefetch and SetThumbnailPrefetch might make the query take longer to execute, but will make accessing large amounts of file information more efficient.

4. Query all the files in a folder and show file provider and availability

   Uses the Provider and IsAvailable* properties to obtain the provider and whether the file is available offline.

Additional important APIs in this sample include:

• CommonFolderQuery enumeration
• CommonFileQuery enumeration
• PropertyPrefetchOptions enumeration

Note The Windows universal samples require Visual Studio 2017 to build and Windows 10 to execute.

To obtain information about Windows 10 development, go to the Windows Dev Center

To obtain information about Microsoft Visual Studio and the tools for developing Windows apps, go to Visual Studio

Related topics

Samples

Programmatic file search sample
File access sample
File and folder thumbnail sample

Reference

Windows.Storage namespace
Windows.Storage.Search namespace

System requirements

Client: Windows 10 build 10500 or higher

Server: Windows Server 2016 Technical Preview build 10500 or higher

Phone: Windows 10 build 10500 or higher

Build the sample

1. If you download the samples ZIP, be sure to unzip the entire archive, not just the folder with the sample you want to build.
2. Start Microsoft Visual Studio 2017 and select File > Open > Project/Solution.
3. Starting in the folder where you unzipped the samples, go to the Samples subfolder, then the subfolder for this specific sample, then the subfolder for your preferred language (C++, C#, or JavaScript). Double-click the Visual Studio Solution (.sln) file.
4. Press Ctrl+Shift+B, or select Build > Build Solution.

Run the sample

The next steps depend on whether you just want to deploy the sample or you want to both deploy and run it.

Deploying the sample

• Select Build > Deploy Solution.

Deploying and running the sample

• To debug the sample and then run it, press F5 or select Debug > Start Debugging. To run the sample without debugging, press Ctrl+F5 or select Debug > Start Without Debugging.