DataRowView Classe

Definizione

public ref class DataRowView : System::ComponentModel::ICustomTypeDescriptor, System::ComponentModel::IDataErrorInfo, System::ComponentModel::IEditableObject, System::ComponentModel::INotifyPropertyChanged

public ref class DataRowView : System::ComponentModel::ICustomTypeDescriptor, System::ComponentModel::IDataErrorInfo, System::ComponentModel::IEditableObject

public class DataRowView : System.ComponentModel.ICustomTypeDescriptor, System.ComponentModel.IDataErrorInfo, System.ComponentModel.IEditableObject, System.ComponentModel.INotifyPropertyChanged

public class DataRowView : System.ComponentModel.ICustomTypeDescriptor, System.ComponentModel.IDataErrorInfo, System.ComponentModel.IEditableObject

type DataRowView = class
    interface ICustomTypeDescriptor
    interface IDataErrorInfo
    interface IEditableObject
    interface INotifyPropertyChanged

type DataRowView = class
    interface ICustomTypeDescriptor
    interface IEditableObject
    interface IDataErrorInfo

type DataRowView = class
    interface ICustomTypeDescriptor
    interface IEditableObject
    interface IDataErrorInfo
    interface INotifyPropertyChanged

Public Class DataRowView
Implements ICustomTypeDescriptor, IDataErrorInfo, IEditableObject, INotifyPropertyChanged

Public Class DataRowView
Implements ICustomTypeDescriptor, IDataErrorInfo, IEditableObject

Ereditarietà

Object

DataRowView

Implementazioni

ICustomTypeDescriptor IDataErrorInfo IEditableObject INotifyPropertyChanged

Esempio

Nell'esempio seguente viene utilizzata la RowVersion proprietà per determinare lo stato di una riga in DataRowView. Vedere RowFilter per un altro esempio con DataRowView.)

private static void DemonstrateRowVersion()
{
    // Create a DataTable with one column.
    DataTable table = new DataTable("Table");
    DataColumn column = new DataColumn("Column");
    table.Columns.Add(column);

    // Add ten rows.
    DataRow row;
    for (int i = 0; i < 10; i++)
    {
        row = table.NewRow();
        row["Column"] = "item " + i;
        table.Rows.Add(row);
    }

    table.AcceptChanges();
    // Create a DataView with the table.
    DataView view = new DataView(table);

    // Change one row's value:
    table.Rows[1]["Column"] = "Hello";

    // Add one row:
    row = table.NewRow();
    row["Column"] = "World";
    table.Rows.Add(row);

    // Set the RowStateFilter to display only added
    // and modified rows.
    view.RowStateFilter = DataViewRowState.Added |
        DataViewRowState.ModifiedCurrent;

    // Print those rows. Output includes "Hello" and "World".
    PrintView(view, "ModifiedCurrent and Added");

    // Set filter to display only originals of modified rows.
    view.RowStateFilter = DataViewRowState.ModifiedOriginal;
    PrintView(view, "ModifiedOriginal");

    // Delete three rows.
    table.Rows[1].Delete();
    table.Rows[2].Delete();
    table.Rows[3].Delete();

    // Set the RowStateFilter to display only deleted rows.
    view.RowStateFilter = DataViewRowState.Deleted;
    PrintView(view, "Deleted");

    // Set filter to display only current rows.
    view.RowStateFilter = DataViewRowState.CurrentRows;
    PrintView(view, "Current");

    // Set filter to display only unchanged rows.
    view.RowStateFilter = DataViewRowState.Unchanged;
    PrintView(view, "Unchanged");

    // Set filter to display only original rows.
    // Current values of unmodified rows are also returned.
    view.RowStateFilter = DataViewRowState.OriginalRows;
    PrintView(view, "OriginalRows");
}

private static void PrintView(DataView view, string label)
{
    Console.WriteLine("\n" + label);
    for (int i = 0; i < view.Count; i++)
    {
        Console.WriteLine(view[i]["Column"]);
        Console.WriteLine("DataViewRow.RowVersion: {0}",
            view[i].RowVersion);
    }
}

Private Sub DemonstrateRowVersion()
    Dim i As Integer
    ' Create a DataTable with one column.
    Dim table As New DataTable("Table")
    Dim column As New DataColumn("Column")
    table.Columns.Add(column)

    ' Add ten rows.
    Dim row As DataRow
    For i = 0 To 9
        row = table.NewRow()
        row("Column") = "item " + i.ToString()
        table.Rows.Add(row)
    Next i
    table.AcceptChanges()

    ' Create a DataView with the table.
    Dim view As New DataView(table)

    ' Change one row's value:
    table.Rows(1)("Column") = "Hello"

    ' Add one row:
    row = table.NewRow()
    row("Column") = "World"
    table.Rows.Add(row)

    ' Set the RowStateFilter to display only added and modified rows.
    view.RowStateFilter = _
       DataViewRowState.Added Or DataViewRowState.ModifiedCurrent

    ' Print those rows. Output includes "Hello" and "World".
    PrintView(view, "ModifiedCurrent and Added")

    ' Set filter to display only originals of modified rows.
    view.RowStateFilter = DataViewRowState.ModifiedOriginal
    PrintView(view, "ModifiedOriginal")

    ' Delete three rows.
    table.Rows(1).Delete()
    table.Rows(2).Delete()
    table.Rows(3).Delete()

    ' Set the RowStateFilter to display only deleted rows.
    view.RowStateFilter = DataViewRowState.Deleted
    PrintView(view, "Deleted")

    ' Set filter to display only current rows.
    view.RowStateFilter = DataViewRowState.CurrentRows
    PrintView(view, "Current")

    ' Set filter to display only unchanged rows.
    view.RowStateFilter = DataViewRowState.Unchanged
    PrintView(view, "Unchanged")

    ' Set filter to display only original rows.
    ' Current values of unmodified rows are also returned.
    view.RowStateFilter = DataViewRowState.OriginalRows
    PrintView(view, "OriginalRows")
End Sub

Private Sub PrintView(ByVal view As DataView, ByVal label As String)
    Console.WriteLine(ControlChars.Cr + label)
    Dim i As Integer
    For i = 0 To view.Count - 1
        Console.WriteLine(view(i)("Column"))
        Console.WriteLine("DataRowView.RowVersion: {0}", _
            view(i).RowVersion)
    Next i
End Sub

Commenti

Ogni volta che vengono visualizzati dati, ad esempio in un DataGrid controllo, è possibile visualizzare una sola versione di ogni riga. La riga visualizzata è un oggetto DataRowView.

Un DataRowView oggetto può avere uno dei quattro stati di versione diversi: Default, Original, Currente Proposed.

Dopo aver BeginEdit richiamato su un DataRowoggetto , qualsiasi valore modificato diventa il Proposed valore . CancelEdit Fino a quando non viene richiamato o EndEdit , la riga ha una Original versione e .Proposed Se CancelEdit viene richiamato, la versione proposta viene rimossa e il valore viene ripristinato su Original. Se EndEdit viene richiamato, l'oggetto DataRowView non ha più una Proposed versione. Il valore proposto diventa invece il valore corrente. I valori predefiniti sono disponibili solo nelle righe con colonne con valori predefiniti definiti.

Proprietà

Metodi

Eventi

Implementazioni dell'interfaccia esplicita

Si applica a

Thread safety

Questo tipo è sicuro per le operazioni di lettura multithreading. È necessario sincronizzare tutte le operazioni di scrittura.

Vedi anche

• DataRow