How to: Reflect Data Source Updates in a Windows Forms Control with the BindingSource

When you use data-bound controls, you sometimes have to respond to changes in the data source when the data source does not raise list-changed events. When you use the BindingSource component to bind your data source to a Windows Forms control, you can notify the control that your data source has changed by calling the ResetBindings method.

Example

The following code example demonstrates using the ResetBindings method to notify a bound control about an update in the data source.

#using <System.Xml.dll>
#using <System.dll>
#using <System.Data.dll>
#using <System.Drawing.dll>
#using <System.Windows.Forms.dll>

using namespace System;
using namespace System::Collections::Generic;
using namespace System::ComponentModel;
using namespace System::Data;
using namespace System::Drawing;
using namespace System::Text;
using namespace System::Xml;
using namespace System::Windows::Forms;
using namespace System::IO;

namespace System_Windows_Forms_UpdateBinding
{
   public ref class Form1: public Form
   {
   public:
      Form1()
      {
         InitializeComponent();
      }

      [STAThread]
      static void Main()
      {
         Application::EnableVisualStyles();
         Application::Run( gcnew Form1 );
      }

   private:
      void Form1_Load( System::Object^ /*sender*/, System::EventArgs^ /*e*/ )
      {
         // The xml to bind to.
         String^ xml = "<US><states>" +
            "<state><name>Washington</name><capital>Olympia</capital></state>" +
            "<state><name>Oregon</name><capital>Salem</capital></state>" +
            "<state><name>California</name><capital>Sacramento</capital></state>" +
            "<state><name>Nevada</name><capital>Carson City</capital></state>" +
            "</states></US>";
         
         // Convert the xml string to bytes and load into a memory stream.
         array<Byte>^ xmlBytes = Encoding::UTF8->GetBytes( xml );
         MemoryStream^ stream = gcnew MemoryStream( xmlBytes,false );
         
         // Create a DataSet and load the xml into it.
         dataSet1->ReadXml( stream );
         
         // Set the DataSource to the DataSet, and the DataMember
         // to state.
         bindingSource1->DataSource = dataSet1;
         bindingSource1->DataMember = "state";

         dataGridView1->DataSource = bindingSource1;
      }

   private:
      void button1_Click( Object^ /*sender*/, EventArgs^ /*e*/ )
      {
         String^ xml = "<US><states>"
            + "<state><name>Washington</name><capital>Olympia</capital> "
            + "<flower>Coast Rhododendron</flower></state>"
            + "<state><name>Oregon</name><capital>Salem</capital>"
            + "<flower>Oregon Grape</flower></state>"
            + "<state><name>California</name><capital>Sacramento</capital>"
            + "<flower>California Poppy</flower></state>"
            + "<state><name>Nevada</name><capital>Carson City</capital>"
            + "<flower>Sagebrush</flower></state>"
            + "</states></US>";
         
         // Convert the xml string to bytes and load into a memory stream.
         array<Byte>^ xmlBytes = Encoding::UTF8->GetBytes( xml );
         MemoryStream^ stream = gcnew MemoryStream( xmlBytes,false );
         
         // Create a DataSet and load the xml into it.
         dataSet2->ReadXml( stream );
         
         // Set the data source.
         bindingSource1->DataSource = dataSet2;
         bindingSource1->ResetBindings( true );
      }

      System::Windows::Forms::Button^ button1;
      System::Windows::Forms::DataGridView^ dataGridView1;
      System::Windows::Forms::BindingSource^ bindingSource1;
      System::Data::DataSet^ dataSet1;
      DataSet^ dataSet2;

      #pragma region Windows Form Designer generated code 

      /// <summary>
      /// Required method for Designer support - do not modify
      /// the contents of this method with the code editor.
      /// </summary>
      void InitializeComponent()
      {
         this->button1 = gcnew System::Windows::Forms::Button;
         this->dataGridView1 = gcnew System::Windows::Forms::DataGridView;
         this->bindingSource1 = gcnew System::Windows::Forms::BindingSource;
         this->dataSet1 = gcnew System::Data::DataSet;
         this->dataSet2 = gcnew System::Data::DataSet;
         ( (System::ComponentModel::ISupportInitialize^)(this->dataGridView1) )->BeginInit();
         ( (System::ComponentModel::ISupportInitialize^)(this->bindingSource1) )->BeginInit();
         ( (System::ComponentModel::ISupportInitialize^)(this->dataSet1) )->BeginInit();
         ( (System::ComponentModel::ISupportInitialize^)(this->dataSet2) )->BeginInit();
         this->SuspendLayout();
         
         //
         // button1
         //
         this->button1->Location = System::Drawing::Point( 98, 222 );
         this->button1->Name = "button1";
         this->button1->TabIndex = 0;
         this->button1->Text = "button1";
         this->button1->Click += gcnew System::EventHandler( this, &Form1::button1_Click );
         
         //
         // dataGridView1
         //
         this->dataGridView1->Dock = System::Windows::Forms::DockStyle::Top;
         this->dataGridView1->Location = System::Drawing::Point( 0, 0 );
         this->dataGridView1->Name = "dataGridView1";
         this->dataGridView1->Size = System::Drawing::Size( 292, 150 );
         this->dataGridView1->TabIndex = 1;
         
         //
         // dataSet1
         //
         this->dataSet1->DataSetName = "NewDataSet";
         this->dataSet1->Locale = gcnew System::Globalization::CultureInfo( "en-US" );
         
         //
         // dataSet2
         //
         this->dataSet2->DataSetName = "NewDataSet";
         this->dataSet2->Locale = gcnew System::Globalization::CultureInfo( "en-US" );
         
         //
         // Form1
         //
         this->ClientSize = System::Drawing::Size( 292, 273 );
         this->Controls->Add( this->dataGridView1 );
         this->Controls->Add( this->button1 );
         this->Name = "Form1";
         this->Text = "Form1";
         this->Load += gcnew EventHandler( this, &Form1::Form1_Load );
         ( (System::ComponentModel::ISupportInitialize^)(this->dataGridView1) )->EndInit();
         ( (System::ComponentModel::ISupportInitialize^)(this->bindingSource1) )->EndInit();
         ( (System::ComponentModel::ISupportInitialize^)(this->dataSet1) )->EndInit();
         ( (System::ComponentModel::ISupportInitialize^)(this->dataSet2) )->EndInit();
         this->ResumeLayout( false );
      }
      #pragma endregion 
   };
}

int main()
{
   System_Windows_Forms_UpdateBinding::Form1::Main();
}
using System;
using System.ComponentModel;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Collections;


namespace System_Windows_Forms_UpdateBinding
{
	class Form1 : Form
	{
        // Declare the objects on the form.
        private Label label1;
        private Label label2;
        private TextBox textBox1;
        private TextBox textBox2;
        private Button button1;
        private BindingSource bindingSource1;
        ArrayList states;

		public Form1()
		{
            // Basic form setup.
            this.button1 = new System.Windows.Forms.Button();
            this.textBox1 = new System.Windows.Forms.TextBox();
            this.label1 = new System.Windows.Forms.Label();
            this.label2 = new System.Windows.Forms.Label();
            this.textBox2 = new System.Windows.Forms.TextBox();
            this.button1.Location = new System.Drawing.Point(12, 18);
            this.button1.Size = new System.Drawing.Size(119, 38);
            this.button1.Text = "RemoveAt(0)";
            this.button1.Click += new System.EventHandler(this.button1_Click);
            this.textBox1.Location = new System.Drawing.Point(55, 75);
            this.textBox1.ReadOnly = true;
            this.textBox1.Size = new System.Drawing.Size(119, 20);
            this.label1.Location = new System.Drawing.Point(12, 110);
            this.label1.Size = new System.Drawing.Size(43, 14);
            this.label1.Text = "Capital:";
            this.label2.Location = new System.Drawing.Point(12, 78);
            this.label2.Size = new System.Drawing.Size(34, 14);
            this.label2.Text = "State:";
            this.textBox2.Location = new System.Drawing.Point(55, 110);
            this.textBox2.Size = new System.Drawing.Size(119, 20);
            this.textBox2.ReadOnly = true;
            this.ClientSize = new System.Drawing.Size(292, 273);
            this.Controls.Add(this.textBox2);
            this.Controls.Add(this.label2);
            this.Controls.Add(this.label1);
            this.Controls.Add(this.textBox1);
            this.Controls.Add(this.button1);
            this.Text = "Form1";

            // Create an ArrayList containing some of the State objects.
            states = new ArrayList();
            states.Add(new State("California", "Sacramento"));
            states.Add(new State("Oregon", "Salem"));
            states.Add(new State("Washington", "Olympia"));
            states.Add(new State("Idaho", "Boise"));
            states.Add(new State("Utah", "Salt Lake City"));
            states.Add(new State("Hawaii", "Honolulu"));
            states.Add(new State("Colorado", "Denver"));
            states.Add(new State("Montana", "Helena"));

            bindingSource1 = new BindingSource();

            // Bind BindingSource1 to the list of states.
            bindingSource1.DataSource = states;

            // Bind the two text boxes to properties of State.
            textBox1.DataBindings.Add("Text", bindingSource1, "Name");
            textBox2.DataBindings.Add("Text", bindingSource1, "Capital");
		}

        private void button1_Click(object sender, EventArgs e)
        {
            // If items remain in the list, remove the first item. 
            if (states.Count > 0)
            {
                states.RemoveAt(0);

                // Call ResetBindings to update the textboxes.
                bindingSource1.ResetBindings(false);
            }
        }

        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.Run(new Form1());

        }
    
        // The State class to add to the ArrayList.
		private class State
		{
			private string stateName;
			public string Name 
			{
				get {return stateName;}
			}

			private string stateCapital;
			public string Capital 
			{
				get {return stateCapital;}
			}

			public State ( string name, string capital)
			{
                stateName = name;
                stateCapital = capital;
			}
		}
              
	}
}
Imports System
Imports System.ComponentModel
Imports System.Drawing
Imports System.Text
Imports System.Windows.Forms
Imports System.Collections


Class Form1
    Inherits Form

    ' Declare the objects on the form.
    Private label1 As Label
    Private label2 As Label
    Private textBox1 As TextBox
    Private textBox2 As TextBox
    Private WithEvents button1 As Button
    Private bindingSource1 As BindingSource
    Private states As ArrayList
    
    Public Sub New()

        ' Basic form setup.
        Me.button1 = New System.Windows.Forms.Button()
        Me.textBox1 = New System.Windows.Forms.TextBox()
        Me.label1 = New System.Windows.Forms.Label()
        Me.label2 = New System.Windows.Forms.Label()
        Me.textBox2 = New System.Windows.Forms.TextBox()
        Me.button1.Location = New System.Drawing.Point(12, 18)
        Me.button1.Size = New System.Drawing.Size(119, 38)
        Me.button1.Text = "RemoveAt(0)"
        Me.textBox1.Location = New System.Drawing.Point(55, 75)
        Me.textBox1.ReadOnly = True
        Me.textBox1.Size = New System.Drawing.Size(119, 20)
        Me.label1.Location = New System.Drawing.Point(12, 110)
        Me.label1.Size = New System.Drawing.Size(43, 14)
        Me.label1.Text = "Capital:"
        Me.label2.Location = New System.Drawing.Point(12, 78)
        Me.label2.Size = New System.Drawing.Size(34, 14)
        Me.label2.Text = "State:"
        Me.textBox2.Location = New System.Drawing.Point(55, 110)
        Me.textBox2.Size = New System.Drawing.Size(119, 20)
        Me.textBox2.ReadOnly = True
        Me.ClientSize = New System.Drawing.Size(292, 273)
        Me.Controls.Add(Me.textBox2)
        Me.Controls.Add(Me.label2)
        Me.Controls.Add(Me.label1)
        Me.Controls.Add(Me.textBox1)
        Me.Controls.Add(Me.button1)
        Me.Text = "Form1"

        ' Create an ArrayList containing some of the State objects.
        states = New ArrayList()
        states.Add(New State("California", "Sacramento"))
        states.Add(New State("Oregon", "Salem"))
        states.Add(New State("Washington", "Olympia"))
        states.Add(New State("Idaho", "Boise"))
        states.Add(New State("Utah", "Salt Lake City"))
        states.Add(New State("Hawaii", "Honolulu"))
        states.Add(New State("Colorado", "Denver"))
        states.Add(New State("Montana", "Helena"))

        bindingSource1 = New BindingSource()

        ' Bind BindingSource1 to the list of states.
        bindingSource1.DataSource = states

        ' Bind the two text boxes to properties of State.
        textBox1.DataBindings.Add("Text", bindingSource1, "Name")
        textBox2.DataBindings.Add("Text", bindingSource1, "Capital")

    End Sub

    Private Sub button1_Click(ByVal sender As Object, ByVal e As EventArgs) _
        Handles button1.Click

        ' If items remain in the list, remove the first item. 
        If states.Count > 0 Then
            states.RemoveAt(0)

            ' Call ResetBindings to update the textboxes.
            bindingSource1.ResetBindings(False)
        End If

    End Sub 'button1_Click
    
    <STAThread()>  _
    Shared Sub Main() 
        Application.EnableVisualStyles()
        Application.Run(New Form1())
    
    End Sub
    
    ' The State class to add to the ArrayList.
    Private Class State
        Private stateName As String

        Public ReadOnly Property Name() As String
            Get
                Return stateName
            End Get
        End Property

        Private stateCapital As String

        Public ReadOnly Property Capital() As String
            Get
                Return stateCapital
            End Get
        End Property

        Public Sub New(ByVal name As String, ByVal capital As String)
            stateName = name
            stateCapital = capital

        End Sub
    End Class
End Class

Compiling the Code

This example requires:

  • References to the System, 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 or Command-line Building With csc.exe. You can also build this example in Visual Studio by pasting the code into a new project. Also see How to: Compile and Run a Complete Windows Forms Code Example Using Visual Studio.

See Also

BindingNavigator
DataGridView
BindingSource
BindingSource Component
How to: Bind a Windows Forms Control to a Type