DataSourceControl Klasse

Definition

public ref class DataSourceControl abstract : System::Web::UI::Control, System::ComponentModel::IListSource, System::Web::UI::IDataSource

[System.ComponentModel.Bindable(false)]
public abstract class DataSourceControl : System.Web.UI.Control, System.ComponentModel.IListSource, System.Web.UI.IDataSource

type DataSourceControl = class
    inherit Control
    interface IDataSource
    interface IListSource

Public MustInherit Class DataSourceControl
Inherits Control
Implements IDataSource, IListSource

Vererbung

Object

Control

DataSourceControl

Abgeleitet

System.Web.UI.WebControls.EntityDataSource

System.Web.UI.WebControls.LinqDataSource

System.Web.UI.WebControls.ObjectDataSource

System.Web.UI.WebControls.QueryableDataSource

System.Web.UI.WebControls.SqlDataSource

Attribute

BindableAttribute

Implementiert

IListSource IDataSource

Beispiele

Im folgenden Codebeispiel wird veranschaulicht, wie eine-Klasse DataSourceControl die-Klasse erweitern kann.The following code example demonstrates how a class can extend the DataSourceControl class. Das CsvDataSource -Steuerelement stellt durch Trennzeichen getrennte Datei Daten dar, die in einer CSV-Datei gespeichert sind.The CsvDataSource control represents comma-separated file data stored in a .csv file. Die CsvDataSource -Klasse stellt eigene Implementierungen GetViewder-, GetViewNames-und-Methoden bereit, da die Basisklassen Implementierungen nicht funktionsfähig sind.The CsvDataSource class provides its own implementations of the GetView, GetViewNames, and other methods, because the base class implementations are not functional.

using System;
using System.Collections;
using System.Data;
using System.IO;
using System.Security.Permissions;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

// The CsvDataSource is a data source control that retrieves its
// data from a comma-separated value file.
[AspNetHostingPermission(SecurityAction.Demand, Level=AspNetHostingPermissionLevel.Minimal)]
public class CsvDataSource : DataSourceControl
{
    public CsvDataSource() : base() {}

    // The comma-separated value file to retrieve data from.
    public string FileName {
        get {
            return ((CsvDataSourceView)this.GetView(String.Empty)).SourceFile;
        }
        set {
            // Only set if it is different.
            if ( ((CsvDataSourceView)this.GetView(String.Empty)).SourceFile != value) {
                ((CsvDataSourceView)this.GetView(String.Empty)).SourceFile = value;
                RaiseDataSourceChangedEvent(EventArgs.Empty);
            }
        }
    }

    // Do not add the column names as a data row. Infer columns if the CSV file does
    // not include column names.
    public bool IncludesColumnNames {
        get {
            return ((CsvDataSourceView)this.GetView(String.Empty)).IncludesColumnNames;
        }
        set {
            // Only set if it is different.
            if ( ((CsvDataSourceView)this.GetView(String.Empty)).IncludesColumnNames != value) {
                ((CsvDataSourceView)this.GetView(String.Empty)).IncludesColumnNames = value;
                RaiseDataSourceChangedEvent(EventArgs.Empty);
            }
        }
    }

    // Return a strongly typed view for the current data source control.
    private CsvDataSourceView view = null;
    protected override DataSourceView GetView(string viewName) {
        if (null == view) {
            view = new CsvDataSourceView(this, String.Empty);
        }
        return view;
    }
    // The ListSourceHelper class calls GetList, which
    // calls the DataSourceControl.GetViewNames method.
    // Override the original implementation to return
    // a collection of one element, the default view name.
    protected override ICollection GetViewNames() {
        ArrayList al = new ArrayList(1);
        al.Add(CsvDataSourceView.DefaultViewName);
        return al as ICollection;
    }
}

// The CsvDataSourceView class encapsulates the
// capabilities of the CsvDataSource data source control.
public class CsvDataSourceView : DataSourceView
{

    public CsvDataSourceView(IDataSource owner, string name) :base(owner, DefaultViewName) {
    }

    // The data source view is named. However, the CsvDataSource
    // only supports one view, so the name is ignored, and the
    // default name used instead.
    public static string DefaultViewName = "CommaSeparatedView";

    // The location of the .csv file.
    private string sourceFile = String.Empty;
    internal string SourceFile {
        get {
            return sourceFile;
        }
        set {
            // Use MapPath when the SourceFile is set, so that files local to the
            // current directory can be easily used.
            string mappedFileName = HttpContext.Current.Server.MapPath(value);
            sourceFile = mappedFileName;
        }
    }

    // Do not add the column names as a data row. Infer columns if the CSV file does
    // not include column names.
    private bool columns = false;
    internal bool IncludesColumnNames {
        get {
            return columns;
        }
        set {
            columns = value;
        }
    }

    // Get data from the underlying data source.
    // Build and return a DataView, regardless of mode.
    protected override IEnumerable ExecuteSelect(DataSourceSelectArguments selectArgs) {
        IEnumerable dataList = null;
        // Open the .csv file.
        if (File.Exists(this.SourceFile)) {
            DataTable data = new DataTable();

            // Open the file to read from.
            using (StreamReader sr = File.OpenText(this.SourceFile)) {
                // Parse the line
                string s = "";
                string[] dataValues;
                DataColumn col;

                // Do the following to add schema.
                dataValues = sr.ReadLine().Split(',');
                // For each token in the comma-delimited string, add a column
                // to the DataTable schema.
                foreach (string token in dataValues) {
                    col = new DataColumn(token,typeof(string));
                    data.Columns.Add(col);
                }

                // Do not add the first row as data if the CSV file includes column names.
                if (! IncludesColumnNames)
                    data.Rows.Add(CopyRowData(dataValues, data.NewRow()));

                // Do the following to add data.
                while ((s = sr.ReadLine()) != null) {
                    dataValues = s.Split(',');
                    data.Rows.Add(CopyRowData(dataValues, data.NewRow()));
                }
            }
            data.AcceptChanges();
            DataView dataView = new DataView(data);
            if (!string.IsNullOrEmpty(selectArgs.SortExpression)) {
                dataView.Sort = selectArgs.SortExpression;
            }
            dataList = dataView;
        }
        else {
            throw new System.Configuration.ConfigurationErrorsException("File not found, " + this.SourceFile);
        }

        if (null == dataList) {
            throw new InvalidOperationException("No data loaded from data source.");
        }

        return dataList;
    }

    private DataRow CopyRowData(string[] source, DataRow target) {
        try {
            for (int i = 0;i < source.Length;i++) {
                target[i] = source[i];
            }
        }
        catch (System.IndexOutOfRangeException) {
            // There are more columns in this row than
            // the original schema allows.  Stop copying
            // and return the DataRow.
            return target;
        }
        return target;
    }
    // The CsvDataSourceView does not currently
    // permit deletion. You can modify or extend
    // this sample to do so.
    public override bool CanDelete {
        get {
            return false;
        }
    }
    protected override int ExecuteDelete(IDictionary keys, IDictionary values)
    {
        throw new NotSupportedException();
    }
    // The CsvDataSourceView does not currently
    // permit insertion of a new record. You can
    // modify or extend this sample to do so.
    public override bool CanInsert {
        get {
            return false;
        }
    }
    protected override int ExecuteInsert(IDictionary values)
    {
        throw new NotSupportedException();
    }
    // The CsvDataSourceView does not currently
    // permit update operations. You can modify or
    // extend this sample to do so.
    public override bool CanUpdate {
        get {
            return false;
        }
    }
    protected override int ExecuteUpdate(IDictionary keys, IDictionary values, IDictionary oldValues)
    {
        throw new NotSupportedException();
    }
}

Imports System.Collections
Imports System.Data
Imports System.IO
Imports System.Security.Permissions
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls

Namespace Samples.AspNet.VB.Controls

' The CsvDataSource is a data source control that retrieves its
' data from a comma-separated value file.
<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
Public Class CsvDataSource
   Inherits DataSourceControl

   Public Sub New()
   End Sub

   ' The comma-separated value file to retrieve data from.
   Public Property FileName() As String
      Get
         Return CType(Me.GetView([String].Empty), CsvDataSourceView).SourceFile
      End Get
      Set
         ' Only set if it is different.
         If CType(Me.GetView([String].Empty), CsvDataSourceView).SourceFile <> value Then
            CType(Me.GetView([String].Empty), CsvDataSourceView).SourceFile = value
            RaiseDataSourceChangedEvent(EventArgs.Empty)
         End If
      End Set
   End Property

   ' Do not add the column names as a data row. Infer columns if the CSV file does
   ' not include column names.

   Public Property IncludesColumnNames() As Boolean
      Get
         Return CType(Me.GetView([String].Empty), CsvDataSourceView).IncludesColumnNames
      End Get
      Set
         ' Only set if it is different.
         If CType(Me.GetView([String].Empty), CsvDataSourceView).IncludesColumnNames <> value Then
            CType(Me.GetView([String].Empty), CsvDataSourceView).IncludesColumnNames = value
            RaiseDataSourceChangedEvent(EventArgs.Empty)
         End If
      End Set
   End Property


   ' Return a strongly typed view for the current data source control.
   Private view As CsvDataSourceView = Nothing

   Protected Overrides Function GetView(viewName As String) As DataSourceView
      If view Is Nothing Then
         view = New CsvDataSourceView(Me, String.Empty)
      End If
      Return view
   End Function 'GetView

   ' The ListSourceHelper class calls GetList, which
   ' calls the DataSourceControl.GetViewNames method.
   ' Override the original implementation to return
   ' a collection of one element, the default view name.
   Protected Overrides Function GetViewNames() As ICollection
      Dim al As New ArrayList(1)
      al.Add(CsvDataSourceView.DefaultViewName)
      Return CType(al, ICollection)
   End Function 'GetViewNames

End Class


' The CsvDataSourceView class encapsulates the
' capabilities of the CsvDataSource data source control.

Public Class CsvDataSourceView
   Inherits DataSourceView

   Public Sub New(owner As IDataSource, name As String)
       MyBase.New(owner, DefaultViewName)
   End Sub

   ' The data source view is named. However, the CsvDataSource
   ' only supports one view, so the name is ignored, and the
   ' default name used instead.
   Public Shared DefaultViewName As String = "CommaSeparatedView"

   ' The location of the .csv file.
   Private aSourceFile As String = [String].Empty

   Friend Property SourceFile() As String
      Get
         Return aSourceFile
      End Get
      Set
         ' Use MapPath when the SourceFile is set, so that files local to the
         ' current directory can be easily used.
         Dim mappedFileName As String
         mappedFileName = HttpContext.Current.Server.MapPath(value)
         aSourceFile = mappedFileName
      End Set
   End Property

   ' Do not add the column names as a data row. Infer columns if the CSV file does
   ' not include column names.
   Private columns As Boolean = False

   Friend Property IncludesColumnNames() As Boolean
      Get
         Return columns
      End Get
      Set
         columns = value
      End Set
   End Property

   ' Get data from the underlying data source.
   ' Build and return a DataView, regardless of mode.
   Protected Overrides Function ExecuteSelect(selectArgs As DataSourceSelectArguments) _
    As System.Collections.IEnumerable
      Dim dataList As IEnumerable = Nothing
      ' Open the .csv file.
      If File.Exists(Me.SourceFile) Then
         Dim data As New DataTable()

         ' Open the file to read from.
         Dim sr As StreamReader = File.OpenText(Me.SourceFile)

         Try
            ' Parse the line
            Dim dataValues() As String
            Dim col As DataColumn

            ' Do the following to add schema.
            dataValues = sr.ReadLine().Split(","c)
            ' For each token in the comma-delimited string, add a column
            ' to the DataTable schema.
            Dim token As String
            For Each token In dataValues
               col = New DataColumn(token, System.Type.GetType("System.String"))
               data.Columns.Add(col)
            Next token

            ' Do not add the first row as data if the CSV file includes column names.
            If Not IncludesColumnNames Then
               data.Rows.Add(CopyRowData(dataValues, data.NewRow()))
            End If

            ' Do the following to add data.
            Dim s As String
            Do
               s = sr.ReadLine()
               If Not s Is Nothing Then
                   dataValues = s.Split(","c)
                   data.Rows.Add(CopyRowData(dataValues, data.NewRow()))
               End If
            Loop Until s Is Nothing

         Finally
            sr.Close()
         End Try

         data.AcceptChanges()
         Dim dataView As New DataView(data)
         If Not selectArgs.SortExpression Is String.Empty Then
             dataView.Sort = selectArgs.SortExpression
         End If
         dataList = dataView
      Else
         Throw New System.Configuration.ConfigurationErrorsException("File not found, " + Me.SourceFile)
      End If

      If dataList is Nothing Then
         Throw New InvalidOperationException("No data loaded from data source.")
      End If

      Return dataList
   End Function 'ExecuteSelect


   Private Function CopyRowData([source]() As String, target As DataRow) As DataRow
      Try
         Dim i As Integer
         For i = 0 To [source].Length - 1
            target(i) = [source](i)
         Next i
      Catch iore As IndexOutOfRangeException
         ' There are more columns in this row than
         ' the original schema allows.  Stop copying
         ' and return the DataRow.
         Return target
      End Try
      Return target
   End Function 'CopyRowData

   ' The CsvDataSourceView does not currently
   ' permit deletion. You can modify or extend
   ' this sample to do so.
   Public Overrides ReadOnly Property CanDelete() As Boolean
      Get
         Return False
      End Get
   End Property

   Protected Overrides Function ExecuteDelete(keys As IDictionary, values As IDictionary) As Integer
      Throw New NotSupportedException()
   End Function 'ExecuteDelete

   ' The CsvDataSourceView does not currently
   ' permit insertion of a new record. You can
   ' modify or extend this sample to do so.
   Public Overrides ReadOnly Property CanInsert() As Boolean
      Get
         Return False
      End Get
   End Property

   Protected Overrides Function ExecuteInsert(values As IDictionary) As Integer
      Throw New NotSupportedException()
   End Function 'ExecuteInsert

   ' The CsvDataSourceView does not currently
   ' permit update operations. You can modify or
   ' extend this sample to do so.
   Public Overrides ReadOnly Property CanUpdate() As Boolean
      Get
         Return False
      End Get
   End Property

   Protected Overrides Function ExecuteUpdate(keys As IDictionary, _
                                              values As IDictionary, _
                                              oldValues As IDictionary) As Integer
      Throw New NotSupportedException()
   End Function 'ExecuteUpdate

End Class
End Namespace

Im folgenden Codebeispiel wird veranschaulicht, wie das CsvDataSource -Steuerelement in einem Web Form verwendet wird.The following code example demonstrates how to use the CsvDataSource control in a Web form.

<%@ Page Language="C#" %>
<%@ Register Tagprefix="aspSample"
             Namespace="Samples.AspNet.CS.Controls" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
  <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
    <form id="form1" runat="server">

      <asp:gridview
          id="GridView1"
          runat="server"
          allowsorting="True"
          datasourceid="CsvDataSource1" />

      <aspSample:CsvDataSource
          id = "CsvDataSource1"
          runat = "server"
          filename = "sample.csv"
          includescolumnnames="True" />

    </form>
  </body>
</html>

<%@ Page Language="VB" %>
<%@ Register Tagprefix="aspSample"
             Namespace="Samples.AspNet.VB.Controls" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
    <head runat="server">
    <title>ASP.NET Example</title>
</head>
<body>
        <form id="form1" runat="server">

            <asp:gridview
                id="GridView1"
                runat="server"
                allowsorting="True"
                datasourceid="CsvDataSource1" />

            <aspSample:CsvDataSource
                id = "CsvDataSource1"
                runat = "server"
                filename = "sample.csv"
                includescolumnnames="True" />

        </form>
    </body>
</html>

Hinweise

ASP.NET unterstützt eine Steuerelement Daten Bindungs Architektur, mit der Webserver Steuerelemente konsistent an Daten gebunden werden können.ASP.NET supports a control data-binding architecture that enables Web server controls to bind to data in a consistent fashion. Webserver Steuerelemente, die an Daten gebunden werden, werden als Daten gebundene Steuerelemente bezeichnet, und die Klassen, die diese Bindung vereinfachen, werden als Datenquellen-Steuerelemente bezeichnet.Web server controls that bind to data are referred to as data-bound controls, and the classes that facilitate that binding are called data source controls. Datenquellensteuerelemente können jede beliebige Datenquelle darstellen: eine relationale Datenbank, eine Datei, einen Stream, ein Geschäftsobjekt usw.Data source controls can represent any data source: a relational database, a file, a stream, a business object, and so on. Datenquellen-Steuerelemente präsentieren Daten auf konsistente Weise für Daten gebundene Steuerelemente, unabhängig von der Quelle oder dem Format der zugrunde liegenden Daten.Data source controls present data in a consistent way to data-bound controls, regardless of the source or format of the underlying data.

Sie verwenden die Datenquellen Steuerelemente, die mit ASP.NET bereitgestellt SqlDataSourcewerden AccessDataSource, einschließlich XmlDataSource, und, um die meisten Webentwicklungs Aufgaben auszuführen.You use the data source controls that are provided with ASP.NET, including SqlDataSource, AccessDataSource, and XmlDataSource, to perform most Web development tasks. Sie verwenden die- DataSourceControl Basisklasse, wenn Sie Ihr eigenes benutzerdefiniertes Datenquellen-Steuerelement implementieren möchten.You use the base DataSourceControl class when you want to implement your own custom data source control.

Obwohl jede Klasse, die die IDataSource -Schnittstelle implementiert, ein Datenquellen Steuerelement ist, erweitern die meisten DataSourceControl ASP.NET-Datenquellen Steuerelemente die abstrakte- IDataSource Klasse, die eine Basis Implementierung der-Schnittstelle bereitstellt.While any class that implements the IDataSource interface is a data source control, most ASP.NET data source controls extend the abstract DataSourceControl class, which provides a base implementation of the IDataSource interface. Die DataSourceControl -Klasse stellt auch eine Implementierung IListSource der-Schnittstelle bereit, die es Ihnen ermöglicht, das DataSource Datenquellen-Steuerelement der-Eigenschaft eines Daten gebundenen Steuer Elements Programm gesteuert zuzuweisen und Daten als einfache Liste an das-Steuerelement zurückzugeben.The DataSourceControl class also provides an implementation of the IListSource interface, which enables you to programmatically assign the data source control to the DataSource property of a data-bound control and return data to the control as a basic list.

Jedes ASP.NET-Steuerelement, das DataBoundControl von der-Klasse abgeleitet wird, kann an ein Datenquellen Steuerelement gebunden werdenAny ASP.NET control that derives from the DataBoundControl class can bind to a data source control. Wenn ein DataBoundControl an ein Datenquellen Steuerelement gebunden ist, wird die Datenbindung automatisch zur Laufzeit ausgeführt.When a DataBoundControl is bound to a data source control, data binding is performed automatically at run time. Sie können auch Datenquellen-Steuerelemente mit ASP.NET-Steuerelementen DataSource verwenden DataSourceID , die eine-Eigenschaft oder eine-Eigenschaft verfügbar machen DataBoundControlund grundlegende Daten Bindungen unterstützenYou can also use data source controls with ASP.NET controls that expose a DataSource or DataSourceID property and support basic data binding, but are not derived from DataBoundControl. Wenn Sie diese Daten gebundenen Steuerelemente verwenden, müssen Sie die DataBind -Methode explizit aufzurufen.When using these data-bound controls, you must explicitly call the DataBind method. Weitere Informationen zur Datenbindung finden Sie unter ASP.NET Data Access Content Map.For more information on data binding, see ASP.NET Data Access Content Map.

Sie können sich ein Datenquellen-Steuerelement als die Kombination DataSourceControl aus dem-Objekt und den zugehörigen Daten Listen vorstellen, die als Datenquellen Sichten bezeichnet werden.You can think of a data source control as the combination of the DataSourceControl object and its associated lists of data, called data source views. Jede Datenliste wird durch ein DataSourceView -Objekt dargestellt.Each list of data is represented by a DataSourceView object. Da der zugrunde liegende Datenspeicher eine oder mehrere Listen mit Daten enthält, DataSourceControl ist immer einem oder mehreren benannten DataSourceView Objekten zugeordnet.Because the underlying data storage contains one or more lists of data, a DataSourceControl is always associated with one or more named DataSourceView objects. Die IDataSource -Schnittstelle definiert die Methoden, die von allen Datenquellen-Steuerelementen für die Interaktion GetViewNames mit Datenquellen Sichten verwendet werden: die-Methode wird verwendet, um die Datenquellen Sichten aufzulisten, GetView die derzeit dem Datenquellen-Steuerelement zugeordnet sind. die-Methode wird verwendet, um eine bestimmte Datenquellen Sicht-Instanz anhand ihres Namens abzurufen.The IDataSource interface defines the methods that all data source controls use to interact with data source views: the GetViewNames method is used to enumerate the data source views currently associated with the data source control, and the GetView method is used to retrieve a specific data source view instance by name.

Sie können sich das Datenquellen-Steuerelement auch als zwei unterschiedliche Schnittstellen vorstellen, mit denen Aufrufer auf Daten zugreifen.You can also think of the data source control as two distinct interfaces that callers use to access data. Bei DataSourceControl der-Klasse handelt es sich um die Schnittstelle, mit der Seiten Entwickler direkt beim entwickeln DataSourceView einer Web Forms Seite interagieren, und die-Klasse ist die Schnittstelle, mit der Daten gebundene Steuerelemente und Daten gebundene Steuerelement Autoren interagieren.The DataSourceControl class is the interface that page developers interact with directly when developing a Web Forms page, and the DataSourceView class is the interface that data-bound controls and data-bound control authors interact with. Da das DataSourceView -Objekt nur zur Laufzeit verfügbar ist, muss jeder Zustand, der für das Datenquellen-Steuerelement oder die Datenquellen Sicht persistent gespeichert ist, direkt vom Datenquellen-Steuerelement verfügbar gemacht werden.Because the DataSourceView object is available only at run time, any state persisted for the data source control or data source view must be exposed directly by the data source control.

Es gibt kein visuelles Rendering von ASP.NET-Datenquellen-Steuerelementen. Sie werden als Steuerelemente implementiert, sodass Sie Sie deklarativ erstellen und optional an der Zustands Verwaltung teilnehmen können.There is no visual rendering of ASP.NET data source controls; they are implemented as controls so you can create them declaratively, and to optionally allow them to participate in state management. Folglich unterstützen Datenquellen-Steuerelemente keine visuellen Funktionen wie EnableTheming oder. SkinIDAs a result, data source controls do not support visual features such as EnableTheming or SkinID.

Konstruktoren

Eigenschaften

Methoden

Ereignisse

Explizite Schnittstellenimplementierungen

Erweiterungsmethoden

Gilt für:

Siehe auch

• IDataSource
• DataSourceView
• DataBoundControl
• HierarchicalDataSourceControl