HierarchicalDataSourceView.Select Method
Assembly: System.Web (in system.web.dll)
The Select method returns an IHierarchicalEnumerable collection of data items in the current view. You can call the GetEnumerator method to get an IEnumerator object and iterate through the collection of data items.
The following code example demonstrates how to override the Select method in a class that derives from the HierarchicalDataSourceView class to retrieve hierarchical FileSystemInfo data from a file system. For security purposes, file system information is displayed only if the data source control is being used in a localhost, authenticated scenario, and only starts with the virtual directory that the Web Forms page using the data source control resides in. Otherwise, the viewPath parameter passed to the constructor of the view object might be used to create a view based on the current file system path. This code example is part of a larger example provided for the HierarchicalDataSourceControl class.
// The FileSystemDataSourceView class encapsulates the // capabilities of the FileSystemDataSource data source control. public class FileSystemDataSourceView : HierarchicalDataSourceView { private string _viewPath; public FileSystemDataSourceView(string viewPath) { // This implementation of HierarchicalDataSourceView does not // use the viewPath parameter but other implementations // could make use of it for retrieving values. _viewPath = viewPath; } // Starting with the rootNode, recursively build a list of // FileSystemInfo nodes, create FileSystemHierarchyData // objects, add them all to the FileSystemHierarchicalEnumerable, // and return the list. public override IHierarchicalEnumerable Select() { HttpRequest currentRequest = HttpContext.Current.Request; // SECURITY: There are many security issues that can be raised // SECURITY: by exposing the file system structure of a Web server // SECURITY: to an anonymous user in a limited trust scenario such as // SECURITY: a Web page served on an intranet or the Internet. // SECURITY: For this reason, the FileSystemDataSource only // SECURITY: shows data when the HttpRequest is received // SECURITY: from a local Web server. In addition, the data source // SECURITY: does not display data to anonymous users. if ( currentRequest.IsAuthenticated && (currentRequest.UserHostAddress == "127.0.0.1" || currentRequest.UserHostAddress == "::1")) { string rootPath = currentRequest.MapPath (currentRequest.ApplicationPath); DirectoryInfo rootDirectory = new DirectoryInfo(rootPath); FileSystemHierarchicalEnumerable fshe = new FileSystemHierarchicalEnumerable(); foreach (FileSystemInfo fsi in rootDirectory.GetFileSystemInfos()) { fshe.Add(new FileSystemHierarchyData(fsi)); } return fshe; } else { throw new NotSupportedException("The FileSystemDataSource only " + "presents data in an authenticated, localhost context."); } } }
Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.
