How to unshare the same Position between two Controls

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Overview

If you have two controls bound to the same datasource, and you do not want them to share the same position, then you must make sure that the BindingContext member of one control differs from the BindingContext member of the other control. If they have the same BindingContext, they will share the same position in the datasource.

If you add for example a ComboBox and a ListBox to a form, the default behavior is for the BindingContext member of each of the two controls to be set to the Form's BindingContext. Thus, the default behavior is for the ListBox and ComboBox to share the same BindingContext, and hence the selection in the ComboBox is synchronized with the current row of the ListBox. If you do not want this behavior, you should create a new BindingContext member for at least one of the controls.

comboBox1.BindingContext = new BindingContext();

Example

The following example shows, how you can you prevent a ComboBox and ListBox bound to the same DataTable from sharing the same current position.

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Data.SqlClient;

namespace Akadia.UnshareDataSource
{
  public class UnshareDataSource : System.Windows.Forms.Form
  {
    private System.Windows.Forms.ListBox listBox1;
    private System.Windows.Forms.ComboBox comboBox1;
    private System.Windows.Forms.Label lblListBox;
    private System.Windows.Forms.Label lblComboBox;
    private System.ComponentModel.Container
      components = null;

    public UnshareDataSource()
    {
      InitializeComponent();
    }

    ....
    ....

    // The main entry point for the application.
    [STAThread]
    static void Main()
    {
      Application.Run(new UnshareDataSource());
    }

    private void UnshareDataSource_Load(
      object sender, System.EventArgs e)
    {

      // Read Table customers into DataSet
      string ConnectionString =
        "data source=xeon;uid=sa;password=manager;
        database=northwind";
      SqlConnection cn = new SqlConnection(ConnectionString);
      string sqlString = "SELECT * FROM customers";

      SqlDataAdapter dataAdapter =
      new SqlDataAdapter(sqlString, cn);
      DataSet dataSet = new DataSet();
      dataAdapter.Fill(dataSet, "customers");

      // Attach dataset's DefaultView to the combobox
      listBox1.DataSource =
        dataSet.Tables["customers"].DefaultView;
      listBox1.DisplayMember = "CustomerID";

      // Attach dataset's DefaultView to the combobox
      // Unshare the Datasource from the listBox1
      comboBox1.BindingContext = new BindingContext();
      comboBox1.DataSource =
        dataSet.Tables["customers"].DefaultView;
      comboBox1.DisplayMember = "CustomerID";
    }
  }
}