IDataSource Schnittstelle

Definition

Stellt eine abstrakte Datenquelle dar, an die sich datengebundene Steuerelemente binden.Represents an abstract data source that data-bound controls bind to.

public interface class IDataSource
public interface IDataSource
type IDataSource = interface
Public Interface IDataSource
Abgeleitet

Beispiele

Im folgenden Codebeispiel wird veranschaulicht, wie eine Klasse die von der IDataSource -Schnittstelle definierten Methoden implementieren kann, um Daten für Daten gebundene Steuerelemente bereitzustellen.The following code example demonstrates how a class can implement the methods defined by the IDataSource interface to provide data to data-bound controls. Das Datenquellen-Steuerelement in diesem Beispiel fungiert als Datenquelle für eine durch Trennzeichen getrennte Datei und kann von einem Daten gebundenen Steuerelement verwendet werden, um durch Trennzeichen getrennte Datei Daten anzuzeigen.The data source control in this example acts as a data source on a comma-separated value file, and can be used by any data-bound control to display comma-separated file data. Dieses Codebeispiel ist Teil eines größeren Beispiels, das für die DataSourceControl -Klasse bereitgestellt wird.This code example is part of a larger example provided for the DataSourceControl class.

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

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 implementieren die IDataSource -Schnittstelle, wenn Sie Ihr eigenes benutzerdefiniertes ASP.NET-Datenquellen-Steuerelement implementieren möchten.You implement the IDataSource interface when you want to implement your own custom ASP.NET data source control.

Jede Klasse, die die IDataSource -Schnittstelle implementiert, ist ein Datenquellen-Steuerelement.Any class that implements the IDataSource interface is a data source control. Die IDataSource -Schnittstelle dient als Grundlage für alle ASP.NET-Datenquellen-Steuerelemente und definiert eines der grundlegenden Konzepte für die Daten Bindungs Architektur mit GetView zwei Methoden: GetViewNames der-Methode und der-Methode.The IDataSource interface serves as the foundation for all ASP.NET data source controls and defines one of the fundamental data-binding architecture concepts with its two methods: the GetView method and the GetViewNames method. Dieses Konzept besteht darin, dass alle Datenquellen-Steuerelemente eine oder mehrere benannte Sichten für Ihre Daten unterstützen.This concept is that all data source controls support one or more named views on their data. Das Datenquellen Sicht-Objekt ähnelt der DataView Abstraktion System.Data im-Namespace: eine Daten bindbare, angepasste Ansicht von Daten zum Sortieren, Filtern und anderen Daten Vorgängen, die in der Sicht definiert sind.The data source view object is similar to the DataView abstraction in the System.Data namespace: a data-bindable, customized view of data for sorting, filtering, and other data operations that the view defines. Im Kern bewirkt ein Datenquellen-Steuerelement nicht mehr als das Abrufen von Sichten zu Daten.At its core, a data source control does nothing more than retrieve views on data.

Ein Datenquellen-Steuerelement kann über ein oder mehrere zugeordnete Datenquellen Sicht-Objekte verfügen.A data source control can have one or more associated data source view objects. Einige Datenquellen Steuerelemente, einschließlich derjenigen, die relationale Daten SqlDataSource Banken AccessDataSourcewie und darstellen, unterstützen nur eine Sicht.Some data source controls, including those that represent relational databases such as SqlDataSource and AccessDataSource, support only one view. Andere Datenquellen-Steuerelemente, einschließlich hierarchischer Datenquellen SiteMapDataSource-Steuerelemente wie, unterstützen viele Ansichten.Other data source controls, including hierarchical data source controls such as SiteMapDataSource, support many views. Die Datenquellen Sicht definiert die Funktionen einer Datenquelle und die Vorgänge, die Sie unterstützt.The data source view defines the capabilities of a data source and the operations that it supports.

Zusammengefasst implementieren Datenquellen Steuerelemente die IDataSource -Schnittstelle, unterstützen eine oder mehrere benannte Sichten für die Daten, die Sie darstellen, und unterstützen immer das Abrufen von Daten aus der Datenquelle, die Sie darstellen.In summary, data source controls implement the IDataSource interface, support one or more named views on the data they represent, and always support data retrieval from the data source they represent. Datenquellen Steuerelemente rufen Daten immer bei Bedarf ab, z DataBind . b. Wenn für ein Daten gebundenes Steuerelement aufgerufen wird.Data source controls always retrieve data on demand, such as when DataBind is called on a data bound control.

Methoden

GetView(String)

Ruft die benannte Datenquellenansicht ab, die dem Datenquellensteuerelement zugeordnet ist.Gets the named data source view associated with the data source control.

GetViewNames()

Ruft eine Auflistung von Namen ab, die die Liste der Ansichtsobjekte darstellt, die der IDataSource-Schnittstelle zugeordnet sind.Gets a collection of names representing the list of view objects associated with the IDataSource interface.

Ereignisse

DataSourceChanged

Tritt ein, wenn ein Datenquellensteuerelement auf eine Weise geändert wurde, die sich auf datengebundene Steuerelemente auswirkt.Occurs when a data source control has changed in some way that affects data-bound controls.

Erweiterungsmethoden

GetDefaultValues(IDataSource)

Ruft die Auflistung von Standardwerten für die angegebene Datenquelle ab.Gets the collection of the default values for the specified data source.

GetMetaTable(IDataSource)

Ruft die Metadaten für eine Tabelle im angegebenen Datenquellenobjekt ab.Gets the metadata for a table in the specified data source object.

TryGetMetaTable(IDataSource, MetaTable)

Bestimmt, ob Tabellenmetadaten verfügbar sind.Determines whether table metadata is available.

Gilt für:

Siehe auch