使用變更通知設計絕佳的資料來源（Windows Forms .NET）

發行項
10/18/2023

Windows Forms 資料系結最重要的概念之一是 變更通知 。若要確保您的資料來源和繫結控制項一律具有最新的資料，您必須新增資料系結的變更通知。具體來說，您想要確保系結控制項會收到對其資料來源所做的變更通知。資料來源會收到控制項系結屬性變更的通知。

根據資料系結的類型而定，有不同類型的變更通知：

簡單系結，其中單一控制項屬性會系結至物件的單一實例。
清單型系結，可包含系結至清單中專案屬性的單一控制項屬性，或系結至物件清單的控制項屬性。

此外，如果您要建立要用於資料系結的 Windows Forms 控制項，則必須將 PropertyName 變更模式套用至控制項。將模式套用至控制項會導致控制項系結屬性的變更傳播至資料來源。

簡單系結的變更通知

對於簡單的系結，當系結屬性的值變更時，商務物件必須提供變更通知。您可以公開商務物件每個屬性的 PropertyNameChanged 事件，以提供變更通知。它也需要將商務物件系結至控制項， BindingSource 以或慣用的方法，讓商務物件實 INotifyPropertyChanged 作介面，並在屬性值變更時引發 PropertyChanged 事件。當您使用實 INotifyPropertyChanged 作介面的物件時，不需要使用 BindingSource 將物件系結至控制項。但建議使用 BindingSource 。

清單型系結的變更通知

Windows Forms 相依于系結清單，以提供 屬性變更 ，並將變更資訊清單列出給繫結控制項。屬性變更是清單專案屬性值變更，而 清單變更 是刪除或新增至清單的專案。因此，用於資料系結的清單必須實 IBindingList 作，以提供這兩種類型的變更通知。 BindingList<T>是的 IBindingList 泛型實作，其設計目的是要與 Windows Forms 資料系結搭配使用。您可以建立 BindingList ，其中包含實作 INotifyPropertyChanged 的商務物件類型，清單會自動將 PropertyChanged 事件轉換成事件 ListChanged 。如果系結清單不是 IBindingList ，您必須使用 BindingSource 元件將物件清單系結至 Windows Forms 控制項。元件 BindingSource 會提供類似于的屬性 BindingList 對清單轉換。如需詳細資訊，請參閱如何：使用 BindingSource 和 INotifyPropertyChanged 介面引發變更通知。

自訂控制項的變更通知

最後，從控制項端，您必須針對設計為系結至資料的每個屬性公開 PropertyName Changed 事件。然後，控制項屬性的變更會傳播至系結的資料來源。如需詳細資訊，請參閱套用 PropertyNameChanged 模式。

套用 PropertyNameChanged 模式

下列程式碼範例示範如何將 PropertyName Changed 模式套用 至自訂控制項。當您實作與 Windows Forms 資料系結引擎搭配使用的自訂控制項時，請套用模式。

// This class implements a simple user control
// that demonstrates how to apply the propertyNameChanged pattern.
[ComplexBindingProperties("DataSource", "DataMember")]
public class CustomerControl : UserControl
{
    private DataGridView dataGridView1;
    private Label label1;
    private DateTime lastUpdate = DateTime.Now;

    public EventHandler DataSourceChanged;

    public object DataSource
    {
        get
        {
            return this.dataGridView1.DataSource;
        }
        set
        {
            if (DataSource != value)
            {
                this.dataGridView1.DataSource = value;
                OnDataSourceChanged();
            }
        }
    }

    public string DataMember
    {
        get { return this.dataGridView1.DataMember; }

        set { this.dataGridView1.DataMember = value; }
    }

    private void OnDataSourceChanged()
    {
        if (DataSourceChanged != null)
        {
            DataSourceChanged(this, new EventArgs());
        }
    }

    public CustomerControl()
    {
        this.dataGridView1 = new System.Windows.Forms.DataGridView();
        this.label1 = new System.Windows.Forms.Label();
        this.dataGridView1.ColumnHeadersHeightSizeMode =
           System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize;
        this.dataGridView1.ImeMode = System.Windows.Forms.ImeMode.Disable;
        this.dataGridView1.Location = new System.Drawing.Point(100, 100);
        this.dataGridView1.Size = new System.Drawing.Size(500,500);
                    
        this.dataGridView1.TabIndex = 1;
        this.label1.AutoSize = true;
        this.label1.Location = new System.Drawing.Point(50, 50);
        this.label1.Name = "label1";
        this.label1.Size = new System.Drawing.Size(76, 13);
        this.label1.TabIndex = 2;
        this.label1.Text = "Customer List:";
        this.Controls.Add(this.label1);
        this.Controls.Add(this.dataGridView1);
        this.Size = new System.Drawing.Size(450, 250);
    }
}

' This class implements a simple user control 
' that demonstrates how to apply the propertyNameChanged pattern.
<ComplexBindingProperties("DataSource", "DataMember")>
Public Class CustomerControl
    Inherits UserControl
    Private dataGridView1 As DataGridView
    Private label1 As Label
    Private lastUpdate As DateTime = DateTime.Now

    Public DataSourceChanged As EventHandler

    Public Property DataSource() As Object
        Get
            Return Me.dataGridView1.DataSource
        End Get
        Set
            If DataSource IsNot Value Then
                Me.dataGridView1.DataSource = Value
                OnDataSourceChanged()
            End If
        End Set
    End Property

    Public Property DataMember() As String
        Get
            Return Me.dataGridView1.DataMember
        End Get
        Set
            Me.dataGridView1.DataMember = Value
        End Set
    End Property

    Private Sub OnDataSourceChanged()
        If (DataSourceChanged IsNot Nothing) Then
            DataSourceChanged(Me, New EventArgs())
        End If

    End Sub

    Public Sub New()
        Me.dataGridView1 = New System.Windows.Forms.DataGridView()
        Me.label1 = New System.Windows.Forms.Label()
        Me.dataGridView1.ColumnHeadersHeightSizeMode =
           System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize
        Me.dataGridView1.ImeMode = System.Windows.Forms.ImeMode.Disable
        Me.dataGridView1.Location = New System.Drawing.Point(19, 55)
        Me.dataGridView1.Size = New System.Drawing.Size(550, 150)
        Me.dataGridView1.TabIndex = 1
        Me.label1.AutoSize = True
        Me.label1.Location = New System.Drawing.Point(19, 23)
        Me.label1.Name = "label1"
        Me.label1.Size = New System.Drawing.Size(76, 13)
        Me.label1.TabIndex = 2
        Me.label1.Text = "Customer List:"
        Me.Controls.Add(Me.label1)
        Me.Controls.Add(Me.dataGridView1)
        Me.Size = New System.Drawing.Size(650, 300)
    End Sub
End Class

實作 INotifyPropertyChanged 介面

下列程式碼範例示範如何實作 INotifyPropertyChanged 介面。在 Windows Forms 資料系結中使用的商務物件上實作介面。實作時，介面會與系結控制項通訊，屬性會在商務物件上變更。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Runtime.CompilerServices;
using System.Windows.Forms;

// Change the namespace to the project name.
namespace binding_control_example
{
    // This form demonstrates using a BindingSource to bind
    // a list to a DataGridView control. The list does not
    // raise change notifications. However the DemoCustomer1 type
    // in the list does.
    public partial class Form3 : Form
    {
        // This button causes the value of a list element to be changed.
        private Button changeItemBtn = new Button();

        // This DataGridView control displays the contents of the list.
        private DataGridView customersDataGridView = new DataGridView();

        // This BindingSource binds the list to the DataGridView control.
        private BindingSource customersBindingSource = new BindingSource();

        public Form3()
        {
            InitializeComponent();

            // Set up the "Change Item" button.
            this.changeItemBtn.Text = "Change Item";
            this.changeItemBtn.Dock = DockStyle.Bottom;
            this.changeItemBtn.Height = 100;
            //this.changeItemBtn.Click +=
              //  new EventHandler(changeItemBtn_Click);
            this.Controls.Add(this.changeItemBtn);

            // Set up the DataGridView.
            customersDataGridView.Dock = DockStyle.Top;
            this.Controls.Add(customersDataGridView);

            this.Size = new Size(400, 200);
        }

        private void Form3_Load(object sender, EventArgs e)
        {
            this.Top = 100;
            this.Left = 100;
            this.Height = 600;
            this.Width = 1000;

            // Create and populate the list of DemoCustomer objects
            // which will supply data to the DataGridView.
            BindingList<DemoCustomer1> customerList = new ();
            customerList.Add(DemoCustomer1.CreateNewCustomer());
            customerList.Add(DemoCustomer1.CreateNewCustomer());
            customerList.Add(DemoCustomer1.CreateNewCustomer());

            // Bind the list to the BindingSource.
            this.customersBindingSource.DataSource = customerList;

            // Attach the BindingSource to the DataGridView.
            this.customersDataGridView.DataSource =
                this.customersBindingSource;
        }

        // Change the value of the CompanyName property for the first
        // item in the list when the "Change Item" button is clicked.
        void changeItemBtn_Click(object sender, EventArgs e)
        {
            // Get a reference to the list from the BindingSource.
            BindingList<DemoCustomer1>? customerList =
                this.customersBindingSource.DataSource as BindingList<DemoCustomer1>;

            // Change the value of the CompanyName property for the
            // first item in the list.
            customerList[0].CustomerName = "Tailspin Toys";
            customerList[0].PhoneNumber = "(708)555-0150";
        }
                
    }

    // This is a simple customer class that
    // implements the IPropertyChange interface.
    public class DemoCustomer1 : INotifyPropertyChanged
    {
        // These fields hold the values for the public properties.
        private Guid idValue = Guid.NewGuid();
        private string customerNameValue = String.Empty;
        private string phoneNumberValue = String.Empty;

        public event PropertyChangedEventHandler PropertyChanged;

        // This method is called by the Set accessor of each property.
        // The CallerMemberName attribute that is applied to the optional propertyName
        // parameter causes the property name of the caller to be substituted as an argument.
        private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }

        // The constructor is private to enforce the factory pattern.
        private DemoCustomer1()
        {
            customerNameValue = "Customer";
            phoneNumberValue = "(312)555-0100";
        }

        // This is the public factory method.
        public static DemoCustomer1 CreateNewCustomer()
        {
            return new DemoCustomer1();
        }

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

        public string CustomerName
        {
            get
            {
                return this.customerNameValue;
            }

            set
            {
                if (value != this.customerNameValue)
                {
                    this.customerNameValue = value;
                    NotifyPropertyChanged();
                }
            }
        }

        public string PhoneNumber
        {
            get
            {
                return this.phoneNumberValue;
            }

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

Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Drawing
Imports System.Runtime.CompilerServices
Imports System.Windows.Forms

' This form demonstrates using a BindingSource to bind
' a list to a DataGridView control. The list does not
' raise change notifications. However the DemoCustomer1 type 
' in the list does.
Public Class Form3
    Inherits System.Windows.Forms.Form
    ' This button causes the value of a list element to be changed.
    Private changeItemBtn As New Button()

    ' This DataGridView control displays the contents of the list.
    Private customersDataGridView As New DataGridView()

    ' This BindingSource binds the list to the DataGridView control.
    Private customersBindingSource As New BindingSource()

    Public Sub New()
        InitializeComponent()
        ' Set up the "Change Item" button.
        Me.changeItemBtn.Text = "Change Item"
        Me.changeItemBtn.Dock = DockStyle.Bottom
        Me.changeItemBtn.Size = New System.Drawing.Size(100, 100)
        AddHandler Me.changeItemBtn.Click, AddressOf changeItemBtn_Click
        Me.Controls.Add(Me.changeItemBtn)

        ' Set up the DataGridView.
        customersDataGridView.Dock = DockStyle.Top
        Me.Controls.Add(customersDataGridView)
        Me.Size = New Size(400, 200)
    End Sub

    Private Sub Form3_Load(ByVal sender As System.Object,
        ByVal e As System.EventArgs) Handles Me.Load
        Me.Top = 100
        Me.Left = 100
        Me.Height = 600
        Me.Width = 1000
        ' Create and populate the list of DemoCustomer1 objects
        ' which will supply data to the DataGridView.
        Dim customerList As New BindingList(Of DemoCustomer1)
        customerList.Add(DemoCustomer1.CreateNewCustomer())
        customerList.Add(DemoCustomer1.CreateNewCustomer())
        customerList.Add(DemoCustomer1.CreateNewCustomer())

        ' Bind the list to the BindingSource.
        Me.customersBindingSource.DataSource = customerList

        ' Attach the BindingSource to the DataGridView.
        Me.customersDataGridView.DataSource = Me.customersBindingSource
    End Sub

    ' This event handler changes the value of the CompanyName
    ' property for the first item in the list.
    Private Sub changeItemBtn_Click(ByVal sender As Object, ByVal e As EventArgs)
        ' Get a reference to the list from the BindingSource.
        Dim customerList As BindingList(Of DemoCustomer1) =
            CType(customersBindingSource.DataSource, BindingList(Of DemoCustomer1))

        ' Change the value of the CompanyName property for the 
        ' first item in the list.
        customerList(0).CustomerName = "Tailspin Toys"
        customerList(0).PhoneNumber = "(708)555-0150"
    End Sub
End Class

' This class implements a simple customer type 
' that implements the IPropertyChange interface.
Public Class DemoCustomer1
    Implements INotifyPropertyChanged

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

    Public Event PropertyChanged As PropertyChangedEventHandler _
        Implements INotifyPropertyChanged.PropertyChanged

    ' This method is called by the Set accessor of each property.
    ' The CallerMemberName attribute that is applied to the optional propertyName
    ' parameter causes the property name of the caller to be substituted as an argument.
    Private Sub NotifyPropertyChanged(<CallerMemberName()> Optional ByVal propertyName As String = Nothing)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
    End Sub

    ' The constructor is private to enforce the factory pattern.
    Private Sub New()
        customerNameValue = "Customer"
        phoneNumberValue = "(312)555-0100"
    End Sub

    ' This is the public factory method.
    Public Shared Function CreateNewCustomer() As DemoCustomer1
        Return New DemoCustomer1()
    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 CustomerName() As String
        Get
            Return Me.customerNameValue
        End Get

        Set(ByVal value As String)
            If Not (value = customerNameValue) Then
                Me.customerNameValue = value
                NotifyPropertyChanged()
            End If
        End Set
    End Property

    Public Property PhoneNumber() As String
        Get
            Return Me.phoneNumberValue
        End Get

        Set(ByVal value As String)
            If Not (value = phoneNumberValue) Then
                Me.phoneNumberValue = value
                NotifyPropertyChanged()
            End If
        End Set
    End Property
End Class

同步處理系結

在 Windows Forms 中實作資料系結期間，多個控制項會系結至相同的資料來源。在某些情況下，可能需要採取額外的步驟，以確保控制項的系結屬性彼此和資料來源保持同步。在兩種情況下，這些步驟是必要的：

如果資料來源未實 IBindingList 作，因此會產生 ListChanged 類型的 ItemChanged 事件。
如果資料來源實作，則為 IEditableObject 。

在先前的案例中，您可以使用 BindingSource 將資料來源系結至控制項。在後者的情況下，您會使用 BindingSource 並處理事件， BindingComplete 並在相關聯的 BindingManagerBase 上呼叫 EndCurrentEdit 。

如需實作此概念的詳細資訊，請參閱 BindingComplete API 參考頁面。

共用方式為

使用變更通知設計絕佳的資料來源（Windows Forms .NET）

簡單系結的變更通知

清單型系結的變更通知

自訂控制項的變更通知

套用 PropertyNameChanged 模式

實作 INotifyPropertyChanged 介面

同步處理系結

另請參閱

意見反應

其他資源

共用方式為

使用變更通知設計絕佳的資料來源 （Windows Forms .NET）

簡單系結的變更通知

清單型系結的變更通知

自訂控制項的變更通知

套用 PropertyNameChanged 模式

實作 INotifyPropertyChanged 介面

同步處理系結

另請參閱

意見反應

其他資源

使用變更通知設計絕佳的資料來源（Windows Forms .NET）