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Control.BindingContext Property

Gets or sets the BindingContext for the control.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

'Declaration
Public Overridable Property BindingContext As BindingContext
'Usage
Dim instance As Control
Dim value As BindingContext

value = instance.BindingContext

instance.BindingContext = value
/** @property */
public BindingContext get_BindingContext ()

/** @property */
public void set_BindingContext (BindingContext value)

public function get BindingContext () : BindingContext

public function set BindingContext (value : BindingContext)

Property Value

A BindingContext for the control.

The BindingContext of a Control is used to return a single BindingManagerBase for all data-bound controls contained by the Control. The BindingManagerBase keeps all controls that are bound to the same data source synchronized. For example, setting the Position property of the BindingManagerBase specifies the item in the underlying list that all data-bound controls point to.

For more information about creating a new BindingContext and assigning it to the BindingContext property, see the BindingContext.

Notes to Inheritors When overriding the BindingContext property in a derived class, use the base class's BindingContext property to extend the base implementation. Otherwise, you must provide all the implementation. You are not required to override both the get and set accessors of the BindingContext property; you can override only one if needed.

The following code example creates four Binding objects to bind five controls, a DateTimePicker and four TextBox controls, to several data sources. The BindingContext is then used to get the BindingManagerBase for each data source.

Protected Sub BindControls()

   ' Create two Binding objects for the first two TextBox 
   '   controls. The data-bound property for both controls 
   '   is the Text property. The data source is a DataSet 
   '   (ds). The data member is the string 
   '   "TableName.ColumnName".
   text1.DataBindings.Add(New Binding _
      ("Text", ds, "customers.custName"))
   text2.DataBindings.Add(New Binding _
      ("Text", ds, "customers.custID"))
   
   ' Bind the DateTimePicker control by adding a new Binding. 
   '   The data member of the DateTimePicker is a 
   '   TableName.RelationName.ColumnName string.
   DateTimePicker1.DataBindings.Add(New Binding _
      ("Value", ds, "customers.CustToOrders.OrderDate"))

   ' Add event delegates for the Parse and Format events to a 
   '   new Binding object, and add the object to the third 
   '   TextBox control's BindingsCollection. The delegates 
   '   must be added before adding the Binding to the 
   '   collection; otherwise, no formatting occurs until 
   '   the Current object of the BindingManagerBase for 
   '   the data source changes.
   Dim b As Binding = New Binding _
      ("Text", ds, "customers.custToOrders.OrderAmount")
   AddHandler b.Parse,  New ConvertEventHandler(AddressOf CurrencyStringToDecimal)      
   AddHandler b.Format, New ConvertEventHandler(AddressOf DecimalToCurrencyString)
   text3.DataBindings.Add(b)

   ' Get the BindingManagerBase for the Customers table.
   bmCustomers = Me.BindingContext(ds, "Customers")

   ' Get the BindingManagerBase for the Orders table using the 
   '   RelationName.
   bmOrders = Me.BindingContext(ds, "customers.CustToOrders")

   ' Bind the fourth TextBox control's Text property to the
   ' third control's Text property.
   text4.DataBindings.Add("Text", text3, "Text")

End Sub


protected void BindControls()
{
    /* Create two Binding objects for the first two TextBox 
       controls. The data-bound property for both controls 
       is the Text property. The data source is a DataSet 
       (ds). The data member is a navigation path in the form: 
       "TableName.ColumnName". 
     */
    text1.get_DataBindings().Add(new Binding("Text", ds, 
        "customers.custName"));
    text2.get_DataBindings().Add(new Binding("Text", ds, 
        "customers.custID"));

    /* Bind the DateTimePicker control by adding a new Binding. 
       The data member of the DateTimePicker is a navigation path:
       TableName.RelationName.ColumnName string. 
     */
    dateTimePicker1.get_DataBindings().Add(new Binding("Value", ds, 
        "customers.CustToOrders.OrderDate"));

    /* Add event delegates for the Parse and Format events to a 
       new Binding object, and add the object to the third 
       TextBox control's BindingsCollection. The delegates 
       must be added before adding the Binding to the 
       collection; otherwise, no formatting occurs until 
       the Current object of the BindingManagerBase for 
       the data source changes. 
     */
    Binding b = new Binding("Text", ds, 
        "customers.custToOrders.OrderAmount");

    b.add_Parse(new ConvertEventHandler(CurrencyStringToDecimal));
    b.add_Format(new ConvertEventHandler(DecimalToCurrencyString));
    text3.get_DataBindings().Add(b);

    // Get the BindingManagerBase for the Customers table. 
    bmCustomers = this.get_BindingContext().get_Item(ds, "Customers");

    /* Get the BindingManagerBase for the Orders table using the 
       RelationName. 
     */
    bmOrders = this.get_BindingContext().get_Item(ds, 
        "customers.CustToOrders");

    /* Bind the fourth TextBox control's Text property to the
       third control's Text property. 
     */
    text4.get_DataBindings().Add("Text", text3, "Text");
} //BindControls

  protected function BindControls()
  {
     /* Create two Binding objects for the first two TextBox 
        controls. The data-bound property for both controls 
        is the Text property. The data source is a DataSet 
        (ds). The data member is the string 
        "TableName.ColumnName". */
     text1.DataBindings.Add(new Binding
     ("Text", ds, "customers.custName"));
     text2.DataBindings.Add(new Binding
     ("Text", ds, "customers.custID"));
     
     /* Bind the DateTimePicker control by adding a new Binding. 
        The data member of the DateTimePicker is a 
        TableName.RelationName.ColumnName string. */
     DateTimePicker1.DataBindings.Add(new 
     Binding("Value", ds, "customers.CustToOrders.OrderDate"));

     /* Add event delegates for the Parse and Format events to a 
        new Binding object, and add the object to the third 
        TextBox control's BindingsCollection. The delegates 
        must be added before adding the Binding to the 
        collection; otherwise, no formatting occurs until 
        the Current object of the BindingManagerBase for 
        the data source changes. */
     var b : Binding = new Binding
        ("Text", ds, "customers.custToOrders.OrderAmount");
     b.add_Parse(CurrencyStringToDecimal);
     b.add_Format(DecimalToCurrencyString);
     text3.DataBindings.Add(b);

     // Get the BindingManagerBase for the Customers table. 
     bmCustomers = this.BindingContext [ds, "Customers"];

     /* Get the BindingManagerBase for the Orders table using the 
        RelationName. */ 
     bmOrders = this.BindingContext[ds, "customers.CustToOrders"];
  }

  private function DecimalToCurrencyString(sender, cevent : ConvertEventArgs)
  {
     /* This method is the Format event handler. Whenever the 
        control displays a new value, the value is converted from 
        its native Decimal type to a string. The ToString method 
        then formats the value as a Currency, by using the 
        formatting character "c". */

     // We can only convert to string type. 
     if(cevent.DesiredType != String.GetType()) return;

     cevent.Value = (Decimal(cevent.Value)).ToString("c");
  }

  private function CurrencyStringToDecimal(sender, cevent : ConvertEventArgs)
  {   
     /* This method is the Parse event-handler. The Parse event 
        occurs whenever the displayed value changes. The static 
        ToDecimal method of the Convert class converts the 
        value back to its native Decimal type. */

     // Can only convert to Decimal type.
     if(cevent.DesiredType != Decimal.GetType()) return;

     cevent.Value = Decimal.Parse(cevent.Value.ToString(),
         NumberStyles.Currency, null);

     /* To see that no precision is lost, print the unformatted 
        value. For example, changing a value to "10.0001" 
        causes the control to display "10.00", but the 
        unformatted value remains "10.0001". */
     Console.WriteLine(cevent.Value);
  }

  protected function button1_Click(sender, e : System.EventArgs)
  {
     // Go to the previous item in the Customer list.
     bmCustomers.Position -= 1;
  }

  protected function button2_Click(sender, e : System.EventArgs)
  {
     // Go to the next item in the Customer list.
     bmCustomers.Position += 1;
  }
   
  protected function button3_Click(sender, e : System.EventArgs)
  {
     // Go to the previous item in the Orders list.
     bmOrders.Position-=1;
  }

  protected function button4_Click(sender, e : System.EventArgs)
  {
     // Go to the next item in the Orders list.
     bmOrders.Position+=1;
  }

  // Create a DataSet with two tables and populate it.
  private function MakeDataSet()
  {
     // Create a DataSet.
     ds = new DataSet("myDataSet");
     
     // Create two DataTables.
     var tCust : DataTable = new DataTable("Customers");
     var tOrders : DataTable= new DataTable("Orders");

     // Create two columns, and add them to the first table.
     var cCustID : DataColumn = new DataColumn("CustID", Int32);
     var cCustName : DataColumn = new DataColumn("CustName");
     tCust.Columns.Add(cCustID);
     tCust.Columns.Add(cCustName);

     // Create three columns, and add them to the second table.
     var cID : DataColumn  = 
        new DataColumn("CustID", Int32);
     var cOrderDate : DataColumn  = 
        new DataColumn("orderDate", DateTime);
     var cOrderAmount : DataColumn = 
        new DataColumn("OrderAmount", Decimal);
     tOrders.Columns.Add(cOrderAmount);
     tOrders.Columns.Add(cID);
     tOrders.Columns.Add(cOrderDate);

     // Add the tables to the DataSet.
     ds.Tables.Add(tCust);
     ds.Tables.Add(tOrders);

     // Create a DataRelation, and add it to the DataSet.
     var dr : DataRelation = new DataRelation
     ("custToOrders", cCustID , cID);
     ds.Relations.Add(dr);
  
     /* Populate the tables. For each customer and order, 
        create need two DataRow variables. */
     var newRow1 : DataRow;
     var newRow2 : DataRow;

     // Create three customers in the Customers Table.
     for(var i : int = 1; i < 4; i++)
     {
        newRow1 = tCust.NewRow();
        newRow1["custID"] = i;
        // Add the row to the Customers table.
        tCust.Rows.Add(newRow1);
     }
     // Give each customer a distinct name.
     tCust.Rows[0]["custName"] = "Alpha";
     tCust.Rows[1]["custName"] = "Beta";
     tCust.Rows[2]["custName"] = "Omega";
     
     // For each customer, create five rows in the Orders table.
     for(var j : int = 1; j < 4; j++)
     {
        for(var k : int = 1; k < 6; k++)
        {
           newRow2 = tOrders.NewRow();
           newRow2["CustID"]= j;
           newRow2["orderDate"]= new DateTime(2001, j, k * 2);
           newRow2["OrderAmount"] = j * 10 + k  * .1;
           // Add the row to the Orders table.
           tOrders.Rows.Add(newRow2);
        }
     }
  }
}


Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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