How to: Raise Change Notifications Using the BindingSource ResetItem Method
Some data sources for your controls do not raise change notifications when items are changed, added, or deleted. With the BindingSource component, you can bind to such data sources and raise a change notification from your code.
Example
This form demonstrates using a BindingSource component to bind a list to a DataGridView control. The list does not raise change notifications, so the ResetItem method on the BindingSource is called when an item in the list is changed. .
Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Diagnostics
Imports System.Drawing
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, so the ResetItem method
' on the BindingSource is used.
Public Class Form1
Inherits System.Windows.Forms.Form
' This button causes the value of a list element to be changed.
Private WithEvents changeItemBtn As New Button()
' This is the DataGridView control that displays the contents
' of the list.
Private customersDataGridView As New DataGridView()
' This is the BindingSource used to bind the list to the
' DataGridView control.
Private WithEvents customersBindingSource As New BindingSource()
Public Sub New()
' Set up the "Change Item" button.
Me.changeItemBtn.Text = "Change Item"
Me.changeItemBtn.Dock = DockStyle.Bottom
Me.Controls.Add(Me.changeItemBtn)
' Set up the DataGridView.
customersDataGridView.Dock = DockStyle.Top
Me.Controls.Add(customersDataGridView)
Me.Size = New Size(800, 200)
End Sub
Private Sub Form1_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Me.Load
' Create and populate the list of DemoCustomer objects
' which will supply data to the DataGridView.
Dim customerList As List(Of DemoCustomer) = _
New List(Of DemoCustomer)
customerList.Add(DemoCustomer.CreateNewCustomer())
customerList.Add(DemoCustomer.CreateNewCustomer())
customerList.Add(DemoCustomer.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) _
Handles changeItemBtn.Click
' Get a reference to the list from the BindingSource.
Dim customerList As List(Of DemoCustomer) = _
CType(Me.customersBindingSource.DataSource, List(Of DemoCustomer))
' Change the value of the CompanyName property for the
' first item in the list.
customerList(0).CompanyName = "Tailspin Toys"
' Call ResetItem to alert the BindingSource that the
' list has changed.
Me.customersBindingSource.ResetItem(0)
End Sub
<STAThread()> _
Shared Sub Main()
Application.EnableVisualStyles()
Application.Run(New Form1())
End Sub
End Class
' This class implements a simple customer type.
Public Class DemoCustomer
' 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
' The constructor is private to enforce the factory pattern.
Private Sub New()
customerName = "no data"
companyNameValue = "no data"
phoneNumberValue = "no data"
End Sub
' 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(ByVal value As String)
Me.companyNameValue = Value
End Set
End Property
Public Property PhoneNumber() As String
Get
Return Me.phoneNumberValue
End Get
Set(ByVal value As String)
Me.phoneNumberValue = Value
End Set
End Property
End Class
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.Common;
using System.Diagnostics;
using System.Drawing;
using System.Data.SqlClient;
using System.Windows.Forms;
// This form demonstrates using a BindingSource to bind
// a list to a DataGridView control. The list does not
// raise change notifications, so the ResetItem method
// on the BindingSource is used.
public class Form1 : System.Windows.Forms.Form
{
// This button causes the value of a list element to be changed.
private Button changeItemBtn = new Button();
// This is the DataGridView control that displays the contents
// of the list.
private DataGridView customersDataGridView = new DataGridView();
// This is the BindingSource used to bind the list to the
// DataGridView control.
private BindingSource customersBindingSource = new BindingSource();
public Form1()
{
// Set up the "Change Item" button.
this.changeItemBtn.Text = "Change Item";
this.changeItemBtn.Dock = DockStyle.Bottom;
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(800, 200);
this.Load += new EventHandler(Form1_Load);
}
private void Form1_Load(System.Object sender, System.EventArgs e)
{
// Create and populate the list of DemoCustomer objects
// which will supply data to the DataGridView.
List<DemoCustomer> customerList = new List<DemoCustomer>();
customerList.Add(DemoCustomer.CreateNewCustomer());
customerList.Add(DemoCustomer.CreateNewCustomer());
customerList.Add(DemoCustomer.CreateNewCustomer());
// Bind the list to the BindingSource.
this.customersBindingSource.DataSource = customerList;
// Attach the BindingSource to the DataGridView.
this.customersDataGridView.DataSource =
this.customersBindingSource;
}
// This event handler changes the value of the CompanyName
// property for the first item in the list.
void changeItemBtn_Click(object sender, EventArgs e)
{
// Get a reference to the list from the BindingSource.
List<DemoCustomer> customerList =
this.customersBindingSource.DataSource as List<DemoCustomer>;
// Change the value of the CompanyName property for the
// first item in the list.
customerList[0].CompanyName = "Tailspin Toys";
// Call ResetItem to alert the BindingSource that the
// list has changed.
this.customersBindingSource.ResetItem(0);
}
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.Run(new Form1());
}
}
// This class implements a simple customer type.
public class DemoCustomer
{
// 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;
// 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
{
this.companyNameValue = value;
}
}
public string PhoneNumber
{
get
{
return this.phoneNumberValue;
}
set
{
this.phoneNumberValue = value;
}
}
}
#using <System.dll>
#using <System.Data.dll>
#using <System.Drawing.dll>
#using <System.EnterpriseServices.dll>
#using <System.Transactions.dll>
#using <System.Windows.Forms.dll>
#using <System.Xml.dll>
using namespace System;
using namespace System::Collections::Generic;
using namespace System::ComponentModel;
using namespace System::Data;
using namespace System::Data::Common;
using namespace System::Data::SqlClient;
using namespace System::Diagnostics;
using namespace System::Drawing;
using namespace System::Windows::Forms;
// This class implements a simple customer type.
public ref class DemoCustomer
{
private:
// These fields hold the values for the public properties.
Guid idValue;
String^ customerName;
String^ companyNameValue;
String^ phoneNumberValue;
// The constructor is private to enforce the factory pattern.
DemoCustomer()
{
idValue = Guid::NewGuid();
customerName = L"no data";
companyNameValue = L"no data";
phoneNumberValue = L"no data";
}
public:
// This is the public factory method.
static DemoCustomer^ CreateNewCustomer()
{
return gcnew DemoCustomer;
}
property Guid ID
{
// This property represents an ID, suitable
// for use as a primary key in a database.
Guid get()
{
return this->idValue;
}
}
property String^ CompanyName
{
String^ get()
{
return this->companyNameValue;
}
void set( String^ value )
{
this->companyNameValue = value;
}
}
property String^ PhoneNumber
{
String^ get()
{
return this->phoneNumberValue;
}
void set( String^ value )
{
this->phoneNumberValue = value;
}
}
};
// This form demonstrates using a BindingSource to bind
// a list to a DataGridView control. The list does not
// raise change notifications, so the ResetItem method
// on the BindingSource is used.
public ref class Form1: public System::Windows::Forms::Form
{
private:
// This button causes the value of a list element to be changed.
Button^ changeItemBtn;
// This is the DataGridView control that displays the contents
// of the list.
DataGridView^ customersDataGridView;
// This is the BindingSource used to bind the list to the
// DataGridView control.
BindingSource^ customersBindingSource;
public:
Form1()
{
changeItemBtn = gcnew Button;
customersDataGridView = gcnew DataGridView;
customersBindingSource = gcnew BindingSource;
// Set up the "Change Item" button.
this->changeItemBtn->Text = L"Change Item";
this->changeItemBtn->Dock = DockStyle::Bottom;
this->changeItemBtn->Click += gcnew EventHandler(
this, &Form1::changeItemBtn_Click );
this->Controls->Add( this->changeItemBtn );
// Set up the DataGridView.
customersDataGridView->Dock = DockStyle::Top;
this->Controls->Add( customersDataGridView );
this->Size = System::Drawing::Size( 800, 200 );
this->Load += gcnew EventHandler( this, &Form1::Form1_Load );
}
private:
void Form1_Load( Object^ /*sender*/, EventArgs^ /*e*/ )
{
// Create and populate the list of DemoCustomer objects
// which will supply data to the DataGridView.
List< DemoCustomer^ >^ customerList = gcnew List< DemoCustomer^ >;
customerList->Add( DemoCustomer::CreateNewCustomer() );
customerList->Add( DemoCustomer::CreateNewCustomer() );
customerList->Add( DemoCustomer::CreateNewCustomer() );
// Bind the list to the BindingSource.
this->customersBindingSource->DataSource = customerList;
// Attach the BindingSource to the DataGridView.
this->customersDataGridView->DataSource =
this->customersBindingSource;
}
// This event handler changes the value of the CompanyName
// property for the first item in the list.
void changeItemBtn_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
{
// Get a reference to the list from the BindingSource.
List< DemoCustomer^ >^ customerList =
static_cast<List< DemoCustomer^ >^>(
this->customersBindingSource->DataSource);
// Change the value of the CompanyName property for the
// first item in the list.
customerList->default[ 0 ]->CompanyName = L"Tailspin Toys";
// Call ResetItem to alert the BindingSource that the
// list has changed.
this->customersBindingSource->ResetItem( 0 );
}
};
int main()
{
Application::EnableVisualStyles();
Application::Run( gcnew Form1 );
}
import System.*;
import System.Collections.Generic.*;
import System.ComponentModel.*;
import System.Data.*;
import System.Data.Common.*;
import System.Diagnostics.*;
import System.Drawing.*;
import System.Data.SqlClient.*;
import System.Windows.Forms.*;
// This form demonstrates using a BindingSource to bind
// a list to a DataGridView control. The list does not
// raise change notifications, so the ResetItem method
// on the BindingSource is used.
public class Form1 extends System.Windows.Forms.Form
{
// This button causes the value of a list element to be changed.
private Button changeItemBtn = new Button();
// This is the DataGridView control that displays the contents
// of the list.
private DataGridView customersDataGridView = new DataGridView();
// This is the BindingSource used to bind the list to the
// DataGridView control.
private BindingSource customersBindingSource = new BindingSource();
public Form1()
{
// Set up the "Change Item" button.
this.changeItemBtn.set_Text("Change Item");
this.changeItemBtn.set_Dock(DockStyle.Bottom);
this.changeItemBtn.add_Click(new EventHandler(changeItemBtn_Click));
this.get_Controls().Add(this.changeItemBtn);
// Set up the DataGridView.
customersDataGridView.set_Dock(DockStyle.Top);
this.get_Controls().Add(customersDataGridView);
this.set_Size(new Size(800, 200));
this.add_Load(new EventHandler(Form1_Load));
} //Form1
private void Form1_Load(Object sender, EventArgs e)
{
// Create and populate the list of DemoCustomer objects
// which will supply data to the DataGridView.
List<DemoCustomer> customerList = new List<DemoCustomer>();
customerList.Add(DemoCustomer.CreateNewCustomer());
customerList.Add(DemoCustomer.CreateNewCustomer());
customerList.Add(DemoCustomer.CreateNewCustomer());
// Bind the list to the BindingSource.
this.customersBindingSource.set_DataSource(customerList);
// Handle the ListChanged event.
this.customersBindingSource.add_ListChanged(
new ListChangedEventHandler(customersBindingSource_ListChanged));
// Attach the BindingSource to the DataGridView.
this.customersDataGridView.set_DataSource(this.customersBindingSource);
} //Form1_Load
// This event handler changes the value of the CompanyName
// property for the first item in the list.
private void changeItemBtn_Click(Object sender, EventArgs e)
{
// Get a reference to the list from the BindingSource.
List<DemoCustomer> customerList = (List<DemoCustomer>)this.
customersBindingSource.get_DataSource();
// Change the value of the CompanyName property for the
// first item in the list.
customerList.get_Item(0).set_CompanyName("Tailspin Toys");
// Call ResetItem to alert the BindingSource that the
// list has changed.
this.customersBindingSource.ResetItem(0);
} //changeItemBtn_Click
// This event handler asserts that the change to the list
// backing the BindingSource is of type ItemChanged.
private void customersBindingSource_ListChanged(Object sender, ListChangedEventArgs e)
{
Trace.Assert(e.get_ListChangedType() == ListChangedType.ItemChanged);
} //customersBindingSource_ListChanged
/** @attribute STAThread()
*/
public static void main(String[] args)
{
Application.EnableVisualStyles();
Application.Run(new Form1());
} //main
} //Form1
// This class implements a simple customer type.
public class DemoCustomer
{
// These fields hold the values for the public properties.
private Guid idValue = Guid.NewGuid();
private String customerName = "";
private String companyNameValue = "";
private String phoneNumberValue = "";
// The constructor is private to enforce the factory pattern.
private DemoCustomer()
{
customerName = "no data";
companyNameValue = "no data";
phoneNumberValue = "no data";
} //DemoCustomer
// This is the public factory method.
public static DemoCustomer CreateNewCustomer()
{
return new DemoCustomer();
} //CreateNewCustomer
// This property represents an ID, suitable
// for use as a primary key in a database.
/** @property
*/
public Guid get_ID()
{
return this.idValue;
}//get_ID
/** @property
*/
public String get_CompanyName()
{
return this.companyNameValue;
}//get_CompanyName
/** @property
*/
public void set_CompanyName(String value)
{
this.companyNameValue = value;
}//set_CompanyName
/** @property
*/
public String get_PhoneNumber()
{
return this.phoneNumberValue;
}//get_PhoneNumber
/** @property
*/
public void set_PhoneNumber(String value)
{
this.phoneNumberValue = value;
}//set_PhoneNumber
} //DemoCustomer
Compiling the Code
This example requires:
- References to the System, System.Data, System.Drawing and System.Windows.Forms assemblies.
For information about building this example from the command line for Visual Basic or Visual C#, see Building from the Command Line (Visual Basic) or Command-Line Building. You can also build this example in Visual Studio by pasting the code into a new project. How to: Compile and Run a Complete Windows Forms Code Example Using Visual Studio
How to: Compile and Run a Complete Windows Forms Code Example Using Visual Studio
How to: Compile and Run a Complete Windows Forms Code Example Using Visual Studio
How to: Compile and Run a Complete Windows Forms Code Example Using Visual Studio
See Also
Tasks
How to: Bind a Windows Forms Control to a Type
Reference
BindingNavigator
DataGridView
BindingSource