DataSourceView DataSourceView DataSourceView DataSourceView Class

Definición

Sirve de clase base para todas las clases de vista de origen de datos, que definen las funciones de los controles de origen de datos.Serves as the base class for all data source view classes, which define the capabilities of data source controls.

public ref class DataSourceView abstract
public abstract class DataSourceView
type DataSourceView = class
Public MustInherit Class DataSourceView
Herencia
DataSourceViewDataSourceViewDataSourceViewDataSourceView
Derivado

Ejemplos

En el ejemplo de código siguiente se muestra cómo DataSourceView extender la clase para crear una clase de vista fuertemente tipada para un control de origen de datos.The following code example demonstrates how to extend the DataSourceView class to create a strongly typed view class for a data source control. La CsVDataSourceView clase define las capacidades CsvDataSource del control de origen de datos y proporciona una implementación para que los controles enlazados a datos utilicen los datos almacenados en archivos de valores separados por comas (. csv).The CsVDataSourceView class defines the capabilities of the CsvDataSource data source control and provides an implementation for data-bound controls to use data stored in comma-separated value (.csv) files. Para obtener más información sobre CsvDataSource el control de origen de datos DataSourceControl , vea la clase.For more information on the CsvDataSource data source control, see the DataSourceControl class.

// 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();
    }
}
' 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 'New

   ' 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 'CsvDataSourceView

Comentarios

ASP.NET admite una arquitectura de enlace de datos que permite que los controles de servidor Web se enlacen a datos de manera coherente.ASP.NET supports a data-binding architecture that enables Web server controls to bind to data in a consistent fashion. Los controles de servidor Web que se enlazan a datos se conocen como controles enlazados a datos y las clases que facilitan ese enlace se denominan controles de origen de datos.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. Los controles de origen de datos pueden representar cualquier origen de datos: una base de datos relacional, un archivo, una secuencia, un objeto comercial, etc.Data source controls can represent any data source: a relational database, a file, a stream, a business object, and so on. Los controles de origen de datos presentan datos de una manera coherente a los controles enlazados a datos, independientemente del origen o el formato de los datos subyacentes.Data source controls present data in a consistent way to data-bound controls, regardless of the source or format of the underlying data.

Los controles de origen de datos que se proporcionan con ASP.net, incluidos SqlDataSource, AccessDataSourcey XmlDataSource, se usan para realizar la mayoría de las tareas de desarrollo web.You use the data source controls that are provided with ASP.NET, including SqlDataSource, AccessDataSource, and XmlDataSource, to perform most Web development tasks. Utilice las clases base DataSourceControl y DataSourceView cuando desee implementar su propio control de origen de datos personalizado.You use the base DataSourceControl and DataSourceView classes when you want to implement your own custom data source control.

Un control de origen de datos se puede considerar como la combinación del IDataSource objeto y sus listas de datos asociadas, llamadas vistas del origen de datos.You can think of a data source control as the combination of the IDataSource object and its associated lists of data, called data source views. Cada lista de datos se representa mediante un DataSourceView objeto.Each list of data is represented by a DataSourceView object. La DataSourceView clase es la clase base para todas las vistas del origen de datos, o listas de datos, asociadas a controles de origen de datos.The DataSourceView class is the base class for all data source views, or lists of data, associated with data source controls. Las vistas del origen de datos definen las capacidades de un control de origen de datos.Data source views define the capabilities of a data source control. Dado que el almacenamiento de datos subyacente contiene una o varias listas de datos, un control de origen de datos siempre está asociado a una o varias vistas del origen de datos con nombre.Because the underlying data storage contains one or more lists of data, a data source control is always associated with one or more named data source views. El control de origen de datos GetViewNames utiliza el método para enumerar las vistas del origen de datos asociadas actualmente con el control GetView de origen de datos y el método para recuperar una instancia específica de la vista del origen de datos por nombre.The data source control uses the GetViewNames method to enumerate the data source views currently associated with the data source control and the GetView method to retrieve a specific data source view instance by name.

Todos DataSourceView los objetos admiten la recuperación de datos del origen de ExecuteSelect datos subyacente mediante el método.All DataSourceView objects support data retrieval from the underlying data source using the ExecuteSelect method. Todas las vistas admiten opcionalmente un conjunto básico de operaciones, incluidas las ExecuteInsertoperaciones ExecuteUpdatecomo, ExecuteDeletey.All views optionally support a basic set of operations, including operations such as ExecuteInsert, ExecuteUpdate, and ExecuteDelete. Un control enlazado a datos puede detectar las capacidades de un control de origen de datos mediante la recuperación de una vista del GetView origen GetViewNames de datos asociada mediante los métodos y, y mediante la consulta de la vista en tiempo de diseño o en tiempo de ejecución.A data-bound control can discover the capabilities of a data source control by retrieving an associated data source view using the GetView and GetViewNames methods, and by querying the view at design time or run time.

Constructores

DataSourceView(IDataSource, String) DataSourceView(IDataSource, String) DataSourceView(IDataSource, String) DataSourceView(IDataSource, String)

Inicializa una nueva instancia de la clase DataSourceView.Initializes a new instance of the DataSourceView class.

Propiedades

CanDelete CanDelete CanDelete CanDelete

Obtiene un valor que indica si el objeto DataSourceView asociado al objeto DataSourceControl actual admite la operación ExecuteDelete(IDictionary, IDictionary).Gets a value indicating whether the DataSourceView object associated with the current DataSourceControl object supports the ExecuteDelete(IDictionary, IDictionary) operation.

CanInsert CanInsert CanInsert CanInsert

Obtiene un valor que indica si el objeto DataSourceView asociado al objeto DataSourceControl actual admite la operación ExecuteInsert(IDictionary).Gets a value indicating whether the DataSourceView object associated with the current DataSourceControl object supports the ExecuteInsert(IDictionary) operation.

CanPage CanPage CanPage CanPage

Obtiene un valor que indica si el objeto DataSourceView asociado al objeto DataSourceControl actual admite la paginación de los datos recuperados por el método ExecuteSelect(DataSourceSelectArguments).Gets a value indicating whether the DataSourceView object associated with the current DataSourceControl object supports paging through the data retrieved by the ExecuteSelect(DataSourceSelectArguments) method.

CanRetrieveTotalRowCount CanRetrieveTotalRowCount CanRetrieveTotalRowCount CanRetrieveTotalRowCount

Obtiene un valor que indica si el objeto DataSourceView asociado al objeto DataSourceControl actual admite la recuperación del número total de filas de datos, en lugar de los propios datos.Gets a value indicating whether the DataSourceView object associated with the current DataSourceControl object supports retrieving the total number of data rows, instead of the data.

CanSort CanSort CanSort CanSort

Obtiene un valor que indica si el objeto DataSourceView asociado al objeto DataSourceControl actual admite la vista ordenada en el origen de datos subyacente.Gets a value indicating whether the DataSourceView object associated with the current DataSourceControl object supports a sorted view on the underlying data source.

CanUpdate CanUpdate CanUpdate CanUpdate

Obtiene un valor que indica si el objeto DataSourceView asociado al objeto DataSourceControl actual admite la operación ExecuteUpdate(IDictionary, IDictionary, IDictionary).Gets a value indicating whether the DataSourceView object associated with the current DataSourceControl object supports the ExecuteUpdate(IDictionary, IDictionary, IDictionary) operation.

Events Events Events Events

Obtiene una lista de delegados de controladores de eventos de la vista de origen de datos.Gets a list of event-handler delegates for the data source view.

Name Name Name Name

Obtiene el nombre de la vista de datos de origen.Gets the name of the data source view.

Métodos

CanExecute(String) CanExecute(String) CanExecute(String) CanExecute(String)

Determina si se puede ejecutar el comando especificado.Determines whether the specified command can be executed.

Delete(IDictionary, IDictionary, DataSourceViewOperationCallback) Delete(IDictionary, IDictionary, DataSourceViewOperationCallback) Delete(IDictionary, IDictionary, DataSourceViewOperationCallback) Delete(IDictionary, IDictionary, DataSourceViewOperationCallback)

Realiza una operación de eliminación asincrónica en la lista de datos que el objeto DataSourceView representa.Performs an asynchronous delete operation on the list of data that the DataSourceView object represents.

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Determina si el objeto especificado es igual al objeto actual.Determines whether the specified object is equal to the current object.

(Inherited from Object)
ExecuteCommand(String, IDictionary, IDictionary) ExecuteCommand(String, IDictionary, IDictionary) ExecuteCommand(String, IDictionary, IDictionary) ExecuteCommand(String, IDictionary, IDictionary)

Ejecuta el comando especificado.Executes the specified command.

ExecuteCommand(String, IDictionary, IDictionary, DataSourceViewOperationCallback) ExecuteCommand(String, IDictionary, IDictionary, DataSourceViewOperationCallback) ExecuteCommand(String, IDictionary, IDictionary, DataSourceViewOperationCallback) ExecuteCommand(String, IDictionary, IDictionary, DataSourceViewOperationCallback)

Ejecuta el comando especificado.Executes the specified command.

ExecuteDelete(IDictionary, IDictionary) ExecuteDelete(IDictionary, IDictionary) ExecuteDelete(IDictionary, IDictionary) ExecuteDelete(IDictionary, IDictionary)

Realiza una operación de eliminación en la lista de datos que el objeto DataSourceView representa.Performs a delete operation on the list of data that the DataSourceView object represents.

ExecuteInsert(IDictionary) ExecuteInsert(IDictionary) ExecuteInsert(IDictionary) ExecuteInsert(IDictionary)

Realiza una operación de inserción en la lista de datos que el objeto DataSourceView representa.Performs an insert operation on the list of data that the DataSourceView object represents.

ExecuteSelect(DataSourceSelectArguments) ExecuteSelect(DataSourceSelectArguments) ExecuteSelect(DataSourceSelectArguments) ExecuteSelect(DataSourceSelectArguments)

Obtiene una lista de datos del espacio de almacenamiento de datos subyacente.Gets a list of data from the underlying data storage.

ExecuteUpdate(IDictionary, IDictionary, IDictionary) ExecuteUpdate(IDictionary, IDictionary, IDictionary) ExecuteUpdate(IDictionary, IDictionary, IDictionary) ExecuteUpdate(IDictionary, IDictionary, IDictionary)

Realiza una operación de actualización en la lista de datos que el objeto DataSourceView representa.Performs an update operation on the list of data that the DataSourceView object represents.

GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Sirve como la función hash predeterminada.Serves as the default hash function.

(Inherited from Object)
GetType() GetType() GetType() GetType()

Obtiene el Type de la instancia actual.Gets the Type of the current instance.

(Inherited from Object)
Insert(IDictionary, DataSourceViewOperationCallback) Insert(IDictionary, DataSourceViewOperationCallback) Insert(IDictionary, DataSourceViewOperationCallback) Insert(IDictionary, DataSourceViewOperationCallback)

Realiza una operación de inserción asincrónica en la lista de datos que el objeto DataSourceView representa.Performs an asynchronous insert operation on the list of data that the DataSourceView object represents.

MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Crea una copia superficial del objeto Object actual.Creates a shallow copy of the current Object.

(Inherited from Object)
OnDataSourceViewChanged(EventArgs) OnDataSourceViewChanged(EventArgs) OnDataSourceViewChanged(EventArgs) OnDataSourceViewChanged(EventArgs)

Genera el evento DataSourceViewChanged.Raises the DataSourceViewChanged event.

RaiseUnsupportedCapabilityError(DataSourceCapabilities) RaiseUnsupportedCapabilityError(DataSourceCapabilities) RaiseUnsupportedCapabilityError(DataSourceCapabilities) RaiseUnsupportedCapabilityError(DataSourceCapabilities)

El método RaiseUnsupportedCapabilitiesError(DataSourceView) llama a este método para comparar las funciones solicitadas para una operación de ExecuteSelect(DataSourceSelectArguments) con las funciones que admite la vista.Called by the RaiseUnsupportedCapabilitiesError(DataSourceView) method to compare the capabilities requested for an ExecuteSelect(DataSourceSelectArguments) operation against those that the view supports.

Select(DataSourceSelectArguments, DataSourceViewSelectCallback) Select(DataSourceSelectArguments, DataSourceViewSelectCallback) Select(DataSourceSelectArguments, DataSourceViewSelectCallback) Select(DataSourceSelectArguments, DataSourceViewSelectCallback)

Obtiene, de forma asincrónica, una lista de datos del espacio de almacenamiento de datos subyacente.Gets a list of data asynchronously from the underlying data storage.

ToString() ToString() ToString() ToString()

Devuelve una cadena que representa el objeto actual.Returns a string that represents the current object.

(Inherited from Object)
Update(IDictionary, IDictionary, IDictionary, DataSourceViewOperationCallback) Update(IDictionary, IDictionary, IDictionary, DataSourceViewOperationCallback) Update(IDictionary, IDictionary, IDictionary, DataSourceViewOperationCallback) Update(IDictionary, IDictionary, IDictionary, DataSourceViewOperationCallback)

Realiza una operación de actualización asincrónica en la lista de datos que el objeto DataSourceView representa.Performs an asynchronous update operation on the list of data that the DataSourceView object represents.

Eventos

DataSourceViewChanged DataSourceViewChanged DataSourceViewChanged DataSourceViewChanged

Se produce cuando la vista de origen de datos ha cambiado.Occurs when the data source view has changed.

Se aplica a

Consulte también: