Comment : implémenter l'interface INotifyPropertyChanged

L'exemple de code suivant illustre l'implémentation de l'interface INotifyPropertyChanged. Implémentez cette interface sur les objets métier utilisés dans la liaison de données Windows Forms. Une fois implémentée, l'interface communique à un contrôle dépendant les modifications des propriétés d'un objet métier.

Exemple

' This class implements a simple customer type 
' that implements the IPropertyChange interface.

Public Class DemoCustomer
    Implements INotifyPropertyChanged

    ' These fields hold the values for the public properties.
    Private idValue As Guid = Guid.NewGuid()
    Private customerName As String = String.Empty
    Private companyNameValue As String = String.Empty
    Private phoneNumberValue As String = String.Empty

    Public Event PropertyChanged As PropertyChangedEventHandler _
      Implements INotifyPropertyChanged.PropertyChanged

    Private Sub NotifyPropertyChanged(ByVal info As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(info))
    End Sub


    ' The constructor is private to enforce the factory pattern.
    Private Sub New() 
        customerName = "no data"
        companyNameValue = "no data"
        phoneNumberValue = "no data"

    End Sub 'New


    ' This is the public factory method.
    Public Shared Function CreateNewCustomer() As DemoCustomer 
        Return New DemoCustomer()

    End Function

    ' This property represents an ID, suitable
    ' for use as a primary key in a database.
    Public ReadOnly Property ID() As Guid
        Get
            Return Me.idValue
        End Get
    End Property


    Public Property CompanyName() As String 
        Get
            Return Me.companyNameValue
        End Get 
        Set
            If value <> Me.companyNameValue Then
                Me.companyNameValue = value
                NotifyPropertyChanged("CompanyName")
            End If
        End Set
    End Property

    Public Property PhoneNumber() As String 
        Get
            Return Me.phoneNumberValue
        End Get 
        Set
            If value <> Me.phoneNumberValue Then
                Me.phoneNumberValue = value
                NotifyPropertyChanged("PhoneNumber")
            End If
        End Set
    End Property
End Class

// This class implements a simple customer type 
// that implements the IPropertyChange interface.
public class DemoCustomer : INotifyPropertyChanged
{
    // These fields hold the values for the public properties.
    private Guid idValue = Guid.NewGuid();
    private string customerName = String.Empty;
    private string companyNameValue = String.Empty;
    private string phoneNumberValue = String.Empty;

    public event PropertyChangedEventHandler PropertyChanged;

    private void NotifyPropertyChanged(String info)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(info));
        }
    }

    // The constructor is private to enforce the factory pattern.
    private DemoCustomer()
    {
        customerName = "no data";
        companyNameValue = "no data";
        phoneNumberValue = "no data";
    }

    // This is the public factory method.
    public static DemoCustomer CreateNewCustomer()
    {
        return new DemoCustomer();
    }

    // This property represents an ID, suitable
    // for use as a primary key in a database.
    public Guid ID
    {
        get
        {
            return this.idValue;
        }
    }

    public string CompanyName
    {
        get {return this.companyNameValue;}

        set
        {
            if (value != this.companyNameValue)
            {
                this.companyNameValue = value;
                NotifyPropertyChanged("CompanyName");
            }
        }
    }
    public string PhoneNumber
    {
        get { return this.phoneNumberValue; }

        set 
        {
            if (value != this.phoneNumberValue)
            {
                this.phoneNumberValue = value;
                NotifyPropertyChanged("PhoneNumber");
            }
        }
    }
}

Compilation du code

Pour compiler l'exemple de code précédent :

• Collez le code dans un fichier de code vide. Utilisez l'objet métier dans une application Windows Forms contenant une méthode Main.

Voir aussi

Tâches

Comment : appliquer le modèle PropertyNameChanged

Comment : générer des notifications de modifications à l'aide d'un BindingSource et de l'interface INotifyPropertyChanged

Concepts

Notification de modifications dans la liaison de données Windows Forms

Autres ressources

Liaison de données Windows Forms