Encapsulates the data source for a form.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
'Declaration <ComplexBindingPropertiesAttribute("DataSource", "DataMember")> _ Public Class BindingSource _ Inherits Component _ Implements IBindingListView, IBindingList, IList, ICollection, _ IEnumerable, ITypedList, ICancelAddNew, ISupportInitializeNotification, ISupportInitialize, _ ICurrencyManagerProvider 'Usage Dim instance As BindingSource
The component serves many purposes. First, it simplifies binding controls on a form to data by providing currency management, change notification, and other services between Windows Forms controls and data sources. This is accomplished by attaching the component to your data source using the DataSource property. For complex binding scenarios you can optionally set the DataMember property to a specific column or list in the data source. You then bind controls to the . All further interaction with the data is accomplished with calls to the component. For examples on how the can simplify the binding process, see How to: Bind Windows Forms Controls to DBNull Database Values and How to: Handle Errors and Exceptions that Occur with Databinding. Navigation and updating of the data source is accomplished through methods such as MoveNext, MoveLast, and Remove. Operations such as sorting and filtering are handled through the Sort and Filter properties. For more information on using sorting and filtering with the , see How to: Sort and Filter ADO.NET Data with the Windows Forms BindingSource Component.
In addition, the component can act as a strongly typed data source. Typically the type of the underlying data source is fixed through one of the following mechanisms:
Use the Add method to add an item to the component.
Set the DataSource property to a list, single object, or type.
Both of these mechanisms create a strongly-typed list. For more information on how to use the to bind to a type, see How to: Bind a Windows Forms Control to a Type. You can also use the to bind your controls to a factory object. For more information on how to do this, see How to: Bind a Windows Forms Control to a Factory Object.
Because a handles both simple and complex data sources, terminology is problematic. Within this class documentation, the term list refers to a data collection within the hosted data source, and item denotes a single element. When discussing functionality associated with complex data sources, the equivalent terms table and row are used.
provides members for accessing the underlying data. The current item can be retrieved through the Current property, and the entire list can be retrieved through the List property. Editing operations are supported on the current item through Current and the RemoveCurrent, EndEdit, CancelEdit and Add and AddNew methods. Although currency management is handled automatically for all underlying data source types, this class exposes a number of events, such as CurrentItemChanged and DataSourceChanged, that allow for customization.
Data sources that are bound to a component can also be navigated and managed with the BindingNavigator class, which provides a VCR-like user interface (UI) for navigating items within a list. Although BindingNavigator can be bound to any data source, it was designed to integrate with a component through its BindingNavigator.BindingSource property.
Many of the members of the class operate on the underlying list represented by the List property and simply refer their operation to the underlying list. Therefore, when the is bound to a custom implementation of IList, the exact behavior of these members may differ from the behavior described in the class documentation. For example, the RemoveAt method calls IList.RemoveAt. The documentation describes the RemoveAt method with the understanding that the RemoveAt method for the underlying IList is correctly implemented.
Imports System Imports System.Collections.Generic Imports System.ComponentModel Imports System.Drawing Imports System.Text Imports System.Windows.Forms Public Class Form1 Inherits Form <STAThread()> _ Shared Sub Main() Application.EnableVisualStyles() Application.Run(New Form1()) End Sub Public Sub New() End Sub Private textBox1 As TextBox Private WithEvents button1 As Button Private listBox1 As ListBox Private components As IContainer Private binding1 As BindingSource Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load listBox1 = New ListBox() textBox1 = New TextBox() binding1 = New BindingSource() button1 = New Button() listBox1.Location = New Point(140, 25) listBox1.Size = New Size(123, 160) textBox1.Location = New Point(23, 70) textBox1.Size = New Size(100, 20) textBox1.Text = "Wingdings" button1.Location = New Point(23, 25) button1.Size = New Size(75, 23) button1.Text = "Search" Me.ClientSize = New Size(292, 266) Me.Controls.Add(Me.button1) Me.Controls.Add(Me.textBox1) Me.Controls.Add(Me.listBox1) Dim fonts As New MyFontList() Dim i As Integer For i = 0 To FontFamily.Families.Length - 1 If FontFamily.Families(i).IsStyleAvailable(FontStyle.Regular) Then fonts.Add(New Font(FontFamily.Families(i), 11.0F, FontStyle.Regular)) End If Next i binding1.DataSource = fonts listBox1.DataSource = binding1 listBox1.DisplayMember = "Name" End Sub Private Sub button1_Click(ByVal sender As Object, ByVal e As EventArgs) _ Handles button1.Click If binding1.SupportsSearching <> True Then MessageBox.Show("Cannot search the list.") Else Dim foundIndex As Integer = binding1.Find("Name", textBox1.Text) If foundIndex > -1 Then listBox1.SelectedIndex = foundIndex Else MessageBox.Show("Font was not found.") End If End If End Sub End Class Public Class MyFontList Inherits BindingList(Of Font) Protected Overrides ReadOnly Property SupportsSearchingCore() As Boolean Get Return True End Get End Property Protected Overrides Function FindCore(ByVal prop As PropertyDescriptor, _ ByVal key As Object) As Integer ' Ignore the prop value and search by family name. Dim i As Integer While i < Count If Items(i).FontFamily.Name.ToLower() = CStr(key).ToLower() Then Return i End If i += 1 End While Return -1 End Function End Class
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.