IEditableObject-Schnittstelle

Stellt Funktionen für die Durchführung eines Commits oder Rollbacks für Änderungen an einem Objekt bereit, das als Datenquelle verwendet wird.

Namespace: System.ComponentModel
Assembly: System (in system.dll)

Syntax

'Declaration
Public Interface IEditableObject
'Usage
Dim instance As IEditableObject

public interface IEditableObject

public interface class IEditableObject

public interface IEditableObject

public interface IEditableObject

Hinweise

Diese Schnittstelle wird normalerweise zum Aufzeichnen der Semantik aus BeginEdit, EndEdit und CancelEdit eines DataRowView verwendet.

Beispiel

Im folgenden Beispiel wird eine einfache Implementierung der IEditableObject-Schnittstelle bereitgestellt. Die Customer-Klasse speichert Kundeninformationen und kann als Auflistung für eine Kundendatenbank verwendet werden. In diesem Beispiel wird davon ausgegangen, dass Sie die CustomerList-Klasse aus dem Beispiel zur IBindingList-Klasse verwendet haben.

Public Class Customer
    Implements IEditableObject

    Structure CustomerData
        Friend id As String
        Friend firstName As String
        Friend lastName As String
    End Structure 

    Public parent As CustomersList
    Private custData As CustomerData
    Private backupData As CustomerData
    Private inTxn As Boolean = False


    ' Implements IEditableObject
    Sub BeginEdit() Implements IEditableObject.BeginEdit
        Console.WriteLine("Start BeginEdit")
        If Not inTxn Then
            Me.backupData = custData
            inTxn = True
            Console.WriteLine(("BeginEdit - " + Me.backupData.lastName))
        End If
        Console.WriteLine("End BeginEdit")
    End Sub 


    Sub CancelEdit() Implements IEditableObject.CancelEdit
        Console.WriteLine("Start CancelEdit")
        If inTxn Then
            Me.custData = backupData
            inTxn = False
            Console.WriteLine(("CancelEdit - " + Me.custData.lastName))
        End If
        Console.WriteLine("End CancelEdit")
    End Sub 


    Sub EndEdit() Implements IEditableObject.EndEdit
        Console.WriteLine(("Start EndEdit" + Me.custData.id + Me.custData.lastName))
        If inTxn Then
            backupData = New CustomerData()
            inTxn = False
            Console.WriteLine(("Done EndEdit - " + Me.custData.id + Me.custData.lastName))
        End If
        Console.WriteLine("End EndEdit")
    End Sub 


    Public Sub New(ByVal ID As String)
        Me.custData = New CustomerData()
        Me.custData.id = ID
        Me.custData.firstName = ""
        Me.custData.lastName = ""
    End Sub 


    Public ReadOnly Property ID() As String
        Get
            Return Me.custData.id
        End Get
    End Property


    Public Property FirstName() As String
        Get
            Return Me.custData.firstName
        End Get
        Set(ByVal Value As String)
            Me.custData.firstName = Value
            Me.OnCustomerChanged()
        End Set
    End Property


    Public Property LastName() As String
        Get
            Return Me.custData.lastName
        End Get
        Set(ByVal Value As String)
            Me.custData.lastName = Value
            Me.OnCustomerChanged()
        End Set
    End Property


    Friend Property Parents() As CustomersList
        Get
            Return Parent
        End Get
        Set(ByVal Value As CustomersList)
            parent = Value
        End Set
    End Property


    Private Sub OnCustomerChanged()
        If Not inTxn And Not (Parent Is Nothing) Then
            Parent.CustomerChanged(Me)
        End If
    End Sub 

    
    Public Overrides Function ToString() As String
        Dim sb As New StringWriter()
        sb.Write(Me.FirstName)
        sb.Write(" ")
        sb.Write(Me.LastName)
        Return sb.ToString()
    End Function 
End Class

public class Customer : IEditableObject 
{
   
    struct CustomerData 
    {
        internal string id ;
        internal string firstName ;
        internal string lastName ;
    }
    
    private CustomersList parent;
    private CustomerData custData; 
    private CustomerData backupData; 
    private bool inTxn = false;

    // Implements IEditableObject
    void IEditableObject.BeginEdit() 
    {
        Console.WriteLine("Start BeginEdit");
        if (!inTxn) 
        {
            this.backupData = custData;
            inTxn = true;
            Console.WriteLine("BeginEdit - " + this.backupData.lastName);
        }
        Console.WriteLine("End BeginEdit");
    }

    void IEditableObject.CancelEdit() 
    {
        Console.WriteLine("Start CancelEdit");
        if (inTxn) 
        {
            this.custData = backupData;
            inTxn = false;
            Console.WriteLine("CancelEdit - " + this.custData.lastName);
        }
        Console.WriteLine("End CancelEdit");
    }

    void IEditableObject.EndEdit() 
    {
        Console.WriteLine("Start EndEdit" + this.custData.id + this.custData.lastName);
        if (inTxn) 
        {
            backupData = new CustomerData();
            inTxn = false;
            Console.WriteLine("Done EndEdit - " + this.custData.id + this.custData.lastName);
        }
        Console.WriteLine("End EndEdit");
    }

    public Customer(string ID) : base() 
    {
        this.custData = new CustomerData();
        this.custData.id = ID;
        this.custData.firstName = "";
        this.custData.lastName = "";
    }

    public string ID 
    {
        get 
        {
            return this.custData.id;
        }
    }
    
    public string FirstName 
    {
        get 
        {
            return this.custData.firstName;
        }
        set 
        {
            this.custData.firstName = value;
            this.OnCustomerChanged();
        }
    }
         
    public string LastName 
    {
        get 
        {
            return this.custData.lastName;
        }
        set 
        {
            this.custData.lastName = value;
            this.OnCustomerChanged();
        }
    }
   
    internal CustomersList Parent 
    {
        get 
        {
            return parent;
        }
        set 
        {
            parent = value ;
        }
    }

    private void OnCustomerChanged() 
    {
        if (!inTxn && Parent != null) 
        {
            Parent.CustomerChanged(this);
        }
    }
    
    public override string ToString() 
    {
        StringWriter sb = new StringWriter();
        sb.Write(this.FirstName);
        sb.Write(" ");
        sb.Write(this.LastName);
        return sb.ToString();
    }   
}

Plattformen

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile für Pocket PC, Windows Mobile für Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.

Versionsinformationen

.NET Framework

Unterstützt in: 2.0, 1.1, 1.0

.NET Compact Framework

Unterstützt in: 2.0, 1.0

Siehe auch

Referenz

IEditableObject-Member
System.ComponentModel-Namespace