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. .

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;
        }
    }
}

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

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