HierarchicalDataSourceView.Select メソッド

定義

ビュー内のすべてのデータ項目の一覧を取得します。Gets a list of all the data items in the view.

public:
 abstract System::Web::UI::IHierarchicalEnumerable ^ Select();
public abstract System.Web.UI.IHierarchicalEnumerable Select ();
abstract member Select : unit -> System.Web.UI.IHierarchicalEnumerable
Public MustOverride Function Select () As IHierarchicalEnumerable

戻り値

IHierarchicalEnumerable

データ項目の IHierarchicalEnumerable コレクション。An IHierarchicalEnumerable collection of data items.

Selectクラスから派生したクラスのメソッドをオーバーライドして、 HierarchicalDataSourceView ファイルシステムから階層データを取得する方法を次のコード例に示し FileSystemInfo ます。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. セキュリティ上の理由から、ファイルシステム情報は、データソースコントロールが localhost の認証シナリオで使用されている場合にのみ表示され、データソースコントロールを使用する Web フォームページが存在する仮想ディレクトリから開始するだけです。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. それ以外の場合は、 viewPath ビューオブジェクトのコンストラクターに渡されたパラメーターを使用して、現在のファイルシステムのパスに基づいてビューを作成できます。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. このコード例は、HierarchicalDataSourceControl クラスのために提供されている大規模な例の一部です。This code example is part of a larger example provided for the HierarchicalDataSourceControl class.

public class FileSystemDataSourceView : HierarchicalDataSourceView
{
    private string _viewPath;

    public FileSystemDataSourceView(string viewPath)
    {
        HttpRequest currentRequest = HttpContext.Current.Request;
        if (viewPath == "")
        {
            _viewPath = currentRequest.MapPath(currentRequest.ApplicationPath);
        }
        else
        {
            _viewPath = Path.Combine(
                currentRequest.MapPath(currentRequest.ApplicationPath),
                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"))
        {
            DirectoryInfo rootDirectory = new DirectoryInfo(_viewPath);
            if (!rootDirectory.Exists)
            {
                return null;
            }

            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.");
        }
    }
}
Public Class FileSystemDataSourceView
    Inherits HierarchicalDataSourceView

    Private _viewPath As String

    Public Sub New(ByVal viewPath As String)
        Dim currentRequest As HttpRequest = HttpContext.Current.Request
        If viewPath = "" Then
            _viewPath = currentRequest.MapPath(currentRequest.ApplicationPath)
        Else
            _viewPath = Path.Combine(currentRequest.MapPath(currentRequest.ApplicationPath), viewPath)
        End If
    End Sub


    ' 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 Overrides Function [Select]() As IHierarchicalEnumerable
        Dim currentRequest As HttpRequest = 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 AndAlso _
            (currentRequest.UserHostAddress = "127.0.0.1" OrElse _
             currentRequest.UserHostAddress = "::1") Then

            Dim rootDirectory As New DirectoryInfo(_viewPath)

            Dim fshe As New FileSystemHierarchicalEnumerable()

            Dim fsi As FileSystemInfo
            For Each fsi In rootDirectory.GetFileSystemInfos()
                fshe.Add(New FileSystemHierarchyData(fsi))
            Next fsi
            Return fshe
        Else
            Throw New NotSupportedException( _
                "The FileSystemDataSource only " + _
                "presents data in an authenticated, localhost context.")
        End If
    End Function 'Select
End Class

注釈

メソッドは、 Select IHierarchicalEnumerable 現在のビュー内のデータ項目のコレクションを返します。The Select method returns an IHierarchicalEnumerable collection of data items in the current view. メソッドを呼び出して GetEnumerator オブジェクトを取得 IEnumerator し、データ項目のコレクションを反復処理することができます。You can call the GetEnumerator method to get an IEnumerator object and iterate through the collection of data items.

適用対象

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