BindingsCollection Classe

Definizione

public ref class BindingsCollection : System::Windows::Forms::BaseCollection

public class BindingsCollection : System.Windows.Forms.BaseCollection

type BindingsCollection = class
    inherit BaseCollection

Public Class BindingsCollection
Inherits BaseCollection

Ereditarietà

Object

MarshalByRefObject

BaseCollection

BindingsCollection

Derivato

System.Windows.Forms.ControlBindingsCollection

Esempio

Nell'esempio seguente viene associata la Text proprietà di un controllo a un TextBox campo in un database.

private:
   void BindTextBoxControl()
   {
      DataSet^ myDataSet = gcnew DataSet;
      /* Insert code to populate the DataSet with tables, 
      columns, and data. */

      // Creates a new Binding object. 
      Binding^ myBinding = gcnew Binding(
         "Text",myDataSet,"customers.custToOrders.OrderAmount" );
      
      // Adds event delegates for the Parse and Format events.
      myBinding->Parse += gcnew ConvertEventHandler( this, &Form1::CurrencyToDecimal );
      myBinding->Format += gcnew ConvertEventHandler( this, &Form1::DecimalToCurrency );
      
      // Adds the new Binding to the BindingsCollection.
      text1->DataBindings->Add( myBinding );
   }

   void DecimalToCurrency( Object^ /*sender*/, ConvertEventArgs^ cevent )
   {
      /* 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". */
      cevent->Value = safe_cast<Decimal ^>(cevent->Value)->ToString(  "c" );
   }

   void CurrencyToDecimal( Object^ /*sender*/, ConvertEventArgs^ cevent )
   {
      /* This method is the Parse event handler. The Parse event 
      occurs whenever the displayed value changes. The static 
      Parse method of the Decimal structure converts the 
      string back to its native Decimal type. */
      cevent->Value = Decimal::Parse( cevent->Value->ToString(),
         NumberStyles::Currency, nullptr );
   }

private void BindTextBoxControl()
{
   DataSet myDataSet = new DataSet();
   /* Insert code to populate the DataSet with tables, 
   columns, and data. */

   // Creates a new Binding object. 
   Binding myBinding = new Binding
   ("Text", myDataSet, "customers.custToOrders.OrderAmount");

   // Adds event delegates for the Parse and Format events.
   myBinding.Parse += new ConvertEventHandler(CurrencyToDecimal);
   myBinding.Format += new ConvertEventHandler(DecimalToCurrency);

   // Adds the new Binding to the BindingsCollection.
   text1.DataBindings.Add(myBinding);
}

private void DecimalToCurrency(object sender, 
   ConvertEventArgs cevent)
{
   /* 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". */
   cevent.Value = ((decimal) cevent.Value).ToString("c");
}

private void CurrencyToDecimal(object sender, 
   ConvertEventArgs cevent)
{   
   /* This method is the Parse event handler. The Parse event 
   occurs whenever the displayed value changes. The static 
   Parse method of the Decimal structure converts the 
   string back to its native Decimal type. */
   cevent.Value = Decimal.Parse(cevent.Value.ToString(),
   NumberStyles.Currency, null);
}

Private Sub BindTextBoxControl()
   Dim myDataSet As New DataSet()
   ' Insert code to populate the DataSet with tables, columns, and data.

   ' Creates a new Binding object. 
   Dim myBinding As New Binding("Text", myDataSet, _
   "customers.custToOrders.OrderAmount")
   
   ' Adds event delegates for the Parse and Format events.
   AddHandler myBinding.Parse, AddressOf CurrencyToDecimal
   AddHandler myBinding.Format, AddressOf DecimalToCurrency
     
   ' Adds the new Binding to the BindingsCollection.
   text1.DataBindings.Add(myBinding)
End Sub 
    
Private Sub DecimalToCurrency(sender As Object, _
   cevent As 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". 
   cevent.Value = CDec(cevent.Value).ToString("c")
End Sub 
    
Private Sub CurrencyToDecimal(sender As Object, _
cevent As ConvertEventArgs)
   ' This method is the Parse event handler. The Parse event
   ' occurs whenever the displayed value changes. The static
   ' Parse method of the Decimal structure converts the 
   ' string back to its native Decimal type. 
   cevent.Value = Decimal.Parse(cevent.Value.ToString(), _
   NumberStyles.Currency, nothing)
   End Sub

Commenti

Il data binding semplice viene eseguito aggiungendo Binding oggetti a un BindingsCollectionoggetto . Qualsiasi oggetto che eredita dalla Control classe può accedere alla BindingsCollectionDataBindings proprietà. Per un elenco di controlli Windows che supportano il data binding, vedere la Binding classe .

Proprietà

Metodi

Eventi

Metodi di estensione

Si applica a

Vedi anche

• CurrencyManager