Binding Clase

Definición

Representa el enlace sencillo entre el valor de propiedad de un objeto y el valor de propiedad de un control.Represents the simple binding between the property value of an object and the property value of a control.

public ref class Binding
[System.ComponentModel.TypeConverter(typeof(System.Windows.Forms.ListBindingConverter))]
public class Binding
type Binding = class
Public Class Binding
Herencia
Binding
Atributos

Ejemplos

En el ejemplo de código siguiente se crea un formulario de Windows Forms con varios controles que muestran el enlace de datos simple.The following code example creates a Windows Form with several controls that demonstrate simple data binding. En el ejemplo se crea un DataSet con dos tablas denominadas Customers y Orders y un DataRelation denominado custToOrders.The example creates a DataSet with two tables named Customers and Orders, and a DataRelation named custToOrders. Cuatro controles (DateTimePicker y tres controles TextBox) son datos enlazados a las columnas de las tablas.Four controls (a DateTimePicker and three TextBox controls) are data bound to columns in the tables. Para cada control, en el ejemplo se crea y agrega un Binding al control a través de la propiedad DataBindings.For each control, the example creates and adds a Binding to the control through the DataBindings property. En el ejemplo se devuelve un BindingManagerBase para cada tabla a través del BindingContext del formulario.The example returns a BindingManagerBase for each table through the form's BindingContext. Cuatro controles Button aumentan o disminuyen la propiedad Position en los objetos BindingManagerBase.Four Button controls increment or decrement the Position property on the BindingManagerBase objects.

#using <system.dll>
#using <system.data.dll>
#using <system.drawing.dll>
#using <system.windows.forms.dll>
#using <system.xml.dll>

using namespace System;
using namespace System::Data;
using namespace System::Drawing;
using namespace System::Globalization;
using namespace System::Windows::Forms;

#define null 0L
public ref class Form1: public Form
{
private:
   System::ComponentModel::Container^ components;
   Button^ button1;
   Button^ button2;
   Button^ button3;
   Button^ button4;
   TextBox^ text1;
   TextBox^ text2;
   TextBox^ text3;
   BindingManagerBase^ bmCustomers;
   BindingManagerBase^ bmOrders;
   DataSet^ ds;
   DateTimePicker^ DateTimePicker1;

public:
   Form1()
   {
      // Required for Windows Form Designer support.
      InitializeComponent();

      // Call SetUp to bind the controls.
      SetUp();
   }

private:
   void InitializeComponent()
   {
      // Create the form and its controls.
      this->components = gcnew System::ComponentModel::Container;
      this->button1 = gcnew Button;
      this->button2 = gcnew Button;
      this->button3 = gcnew Button;
      this->button4 = gcnew Button;
      this->text1 = gcnew TextBox;
      this->text2 = gcnew TextBox;
      this->text3 = gcnew TextBox;
      this->DateTimePicker1 = gcnew DateTimePicker;
      this->Text =  "Binding Sample";
      this->ClientSize = System::Drawing::Size( 450, 200 );
      button1->Location = System::Drawing::Point( 24, 16 );
      button1->Size = System::Drawing::Size( 64, 24 );
      button1->Text =  "<";
      button1->Click += gcnew System::EventHandler( this, &Form1::button1_Click );
      button2->Location = System::Drawing::Point( 90, 16 );
      button2->Size = System::Drawing::Size( 64, 24 );
      button2->Text =  ">";
      button2->Click += gcnew System::EventHandler( this, &Form1::button2_Click );
      button3->Location = System::Drawing::Point( 90, 100 );
      button3->Size = System::Drawing::Size( 64, 24 );
      button3->Text =  "<";
      button3->Click += gcnew System::EventHandler( this, &Form1::button3_Click );
      button4->Location = System::Drawing::Point( 150, 100 );
      button4->Size = System::Drawing::Size( 64, 24 );
      button4->Text =  ">";
      button4->Click += gcnew System::EventHandler( this, &Form1::button4_Click );
      text1->Location = System::Drawing::Point( 24, 50 );
      text1->Size = System::Drawing::Size( 150, 24 );
      text2->Location = System::Drawing::Point( 190, 50 );
      text2->Size = System::Drawing::Size( 150, 24 );
      text3->Location = System::Drawing::Point( 290, 150 );
      text3->Size = System::Drawing::Size( 150, 24 );
      DateTimePicker1->Location = System::Drawing::Point( 90, 150 );
      DateTimePicker1->Size = System::Drawing::Size( 200, 800 );
      this->Controls->Add( button1 );
      this->Controls->Add( button2 );
      this->Controls->Add( button3 );
      this->Controls->Add( button4 );
      this->Controls->Add( text1 );
      this->Controls->Add( text2 );
      this->Controls->Add( text3 );
      this->Controls->Add( DateTimePicker1 );
   }

public:
   ~Form1()
   {
      if ( components != nullptr )
      {
         delete components;
      }
   }

private:
   void SetUp()
   {
      // Create a DataSet with two tables and one relation.
      MakeDataSet();
      BindControls();
   }

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 the 
              "TableName.ColumnName" string. */
      text1->DataBindings->Add( gcnew Binding( "Text",ds,"customers.custName" ) );
      text2->DataBindings->Add( gcnew 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( gcnew 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 = gcnew Binding( "Text",ds,"customers.custToOrders.OrderAmount" );
      b->Parse += gcnew ConvertEventHandler( this, &Form1::CurrencyStringToDecimal );
      b->Format += gcnew ConvertEventHandler( this, &Form1::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:
   void DecimalToCurrencyString( 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". */
      // The application can only convert to string type. 
      if ( cevent->DesiredType != String::typeid )
            return;

      cevent->Value = (dynamic_cast<Decimal^>(cevent->Value))->ToString( "c" );
   }

   void CurrencyStringToDecimal( Object^ /*sender*/, ConvertEventArgs^ cevent )
   {
      /* 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::typeid )
            return;

      cevent->Value = Decimal::Parse( cevent->Value->ToString(), NumberStyles::Currency, nullptr );
      
      /* 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 );
   }

private:
   void button1_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Go to the previous item in the Customer list.
      bmCustomers->Position -= 1;
   }

   void button2_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      // Go to the next item in the Customer list.
      bmCustomers->Position += 1;
   }

   void button3_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      
      // Go to the previous item in the Orders list.
      bmOrders->Position = bmOrders->Position - 1;
   }

   void button4_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      
      // Go to the next item in the Orders list.
      bmOrders->Position = bmOrders->Position + 1;
   }

private:

   // Create a DataSet with two tables and populate it.
   void MakeDataSet()
   {
      // Create a DataSet.
      ds = gcnew DataSet( "myDataSet" );

      // Create two DataTables.
      DataTable^ tCust = gcnew DataTable( "Customers" );
      DataTable^ tOrders = gcnew DataTable( "Orders" );

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

      // Create three columns, and add them to the second table.
      DataColumn^ cID = gcnew DataColumn( "CustID",Int32::typeid );
      DataColumn^ cOrderDate = gcnew DataColumn( "orderDate",DateTime::typeid );
      DataColumn^ cOrderAmount = gcnew DataColumn( "OrderAmount",Decimal::typeid );
      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.
      DataRelation^ dr = gcnew DataRelation( "custToOrders",cCustID,cID );
      ds->Relations->Add( dr );
      
      /* Populate the tables. For each customer and order, 
              create two DataRow variables. */
      DataRow^ newRow1; // = new DataRow();

      DataRow^ newRow2; // = new DataRow();

      // Create three customers in the Customers Table.
      for ( int i = 1; i < 4; i++ )
      {
         newRow1 = tCust->NewRow();
         newRow1[ "custID" ] = i;
         
         // Add the row to the Customers table.
         tCust->Rows->Add( newRow1 );

      }
      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 ( int i = 1; i < 4; i++ )
      {
         for ( int j = 1; j < 6; j++ )
         {
            newRow2 = tOrders->NewRow();
            newRow2[ "CustID" ] = i;
            newRow2[ "orderDate" ] = System::DateTime( 2001, i, j * 2 );
            newRow2[ "OrderAmount" ] = i * 10 + j * .1;
            
            // Add the row to the Orders table.
            tOrders->Rows->Add( newRow2 );
         }
      }
   }
};

int main()
{
   Application::Run( gcnew Form1 );
}
using System;
using System.Data;
using System.Drawing;
using System.Globalization;
using System.Windows.Forms;

public class Form1 : System.Windows.Forms.Form
{
   private System.ComponentModel.Container components;
   private Button button1;
   private Button button2;
   private Button button3;
   private Button button4;
   private TextBox text1;
   private TextBox text2;
   private TextBox text3;

   private BindingManagerBase bmCustomers;
   private BindingManagerBase bmOrders;
   private DataSet ds;
   private DateTimePicker DateTimePicker1;

   public Form1()
   {
      // Required for Windows Form Designer support.
      InitializeComponent();
      // Call SetUp to bind the controls.
      SetUp();
   }
 
   private void InitializeComponent()
   {
      // Create the form and its controls.
      this.components = new System.ComponentModel.Container();
      this.button1 = new System.Windows.Forms.Button();
      this.button2 = new System.Windows.Forms.Button();
      this.button3 = new System.Windows.Forms.Button();
      this.button4 = new System.Windows.Forms.Button();
      
      this.text1= new System.Windows.Forms.TextBox();
      this.text2= new System.Windows.Forms.TextBox();
      this.text3= new System.Windows.Forms.TextBox();
      
      this.DateTimePicker1 = new DateTimePicker();
      
      this.Text = "Binding Sample";
      this.ClientSize = new System.Drawing.Size(450, 200);
      
      button1.Location = new System.Drawing.Point(24, 16);
      button1.Size = new System.Drawing.Size(64, 24);
      button1.Text = "<";
      button1.Click+=new System.EventHandler(button1_Click);

      button2.Location = new System.Drawing.Point(90, 16);
      button2.Size = new System.Drawing.Size(64, 24);
      button2.Text = ">";
      button2.Click+=new System.EventHandler(button2_Click);

      button3.Location = new System.Drawing.Point(90, 100);
      button3.Size = new System.Drawing.Size(64, 24);
      button3.Text = "<";
      button3.Click+=new System.EventHandler(button3_Click);

      button4.Location = new System.Drawing.Point(150, 100);
      button4.Size = new System.Drawing.Size(64, 24);
      button4.Text = ">";
      button4.Click+=new System.EventHandler(button4_Click);

      text1.Location = new System.Drawing.Point(24, 50);
      text1.Size = new System.Drawing.Size(150, 24);

      text2.Location = new System.Drawing.Point(190, 50);
      text2.Size = new System.Drawing.Size(150, 24);

      text3.Location = new System.Drawing.Point(290, 150);
      text3.Size = new System.Drawing.Size(150, 24);
      
      DateTimePicker1.Location = new System.Drawing.Point(90, 150);
      DateTimePicker1.Size = new System.Drawing.Size(200, 800);
      
      this.Controls.Add(button1);
      this.Controls.Add(button2);
      this.Controls.Add(button3);
      this.Controls.Add(button4);
      this.Controls.Add(text1);
      this.Controls.Add(text2);
      this.Controls.Add(text3);
      this.Controls.Add(DateTimePicker1);
   }

   protected override void Dispose( bool disposing ){
      if( disposing ){
         if (components != null){
            components.Dispose();}
      }
      base.Dispose( disposing );
   }
   public static void Main()
   {
      Application.Run(new Form1());
   }
   
   private void SetUp()
   {
      // Create a DataSet with two tables and one relation.
      MakeDataSet();
      BindControls();
   }

   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 the  
         "TableName.ColumnName" string. */
      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. */
      Binding b = new Binding
         ("Text", ds, "customers.custToOrders.OrderAmount");
      b.Parse+=new ConvertEventHandler(CurrencyStringToDecimal);
      b.Format+=new ConvertEventHandler(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 void DecimalToCurrencyString(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". */

      // The application can only convert to string type. 
      if(cevent.DesiredType != typeof(string)) return;

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

   private void CurrencyStringToDecimal(object sender, ConvertEventArgs cevent)
   {   
      /* 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 != typeof(decimal)) 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);
   }

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

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

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

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

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

      // Create three columns, and add them to the second table.
      DataColumn cID = 
         new DataColumn("CustID", typeof(int));
      DataColumn cOrderDate = 
         new DataColumn("orderDate",typeof(DateTime));
      DataColumn cOrderAmount = 
         new DataColumn("OrderAmount", typeof(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.
      DataRelation dr = new DataRelation
      ("custToOrders", cCustID , cID);
      ds.Relations.Add(dr);
   
      /* Populate the tables. For each customer and order, 
         create two DataRow variables. */
      DataRow newRow1;
      DataRow newRow2;

      // Create three customers in the Customers Table.
      for(int i = 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(int i = 1; i < 4; i++)
      {
         for(int j = 1; j < 6; j++)
         {
            newRow2 = tOrders.NewRow();
            newRow2["CustID"]= i;
            newRow2["orderDate"]= new DateTime(2001, i, j * 2);
            newRow2["OrderAmount"] = i * 10 + j  * .1;
            // Add the row to the Orders table.
            tOrders.Rows.Add(newRow2);
         }
      }
   }
 }

Imports System.ComponentModel
Imports System.Data
Imports System.Drawing
Imports System.Globalization
Imports System.Windows.Forms

Public Class Form1
   Inherits Form

   Private components As Container
   Private button1 As Button
   Private button2 As Button
   Private button3 As Button
   Private button4 As Button
   Private text1 As TextBox
   Private text2 As TextBox
   Private text3 As TextBox

   Private bmCustomers As BindingManagerBase
   Private bmOrders As BindingManagerBase
   Private ds As DataSet
   Private DateTimePicker1 As DateTimePicker
   
   Public Sub New
      ' Required for Windows Form Designer support.
      InitializeComponent
      ' Call SetUp to bind the controls.
      SetUp
   End Sub

   Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
      If disposing Then
         If (components IsNot Nothing) Then
            components.Dispose()
         End If
      End If
      MyBase.Dispose(disposing)
    End Sub


   Private Sub InitializeComponent
      ' Create the form and its controls.
      With Me
         .components = New Container
         .button1 = New Button
         .button2 = New Button
         .button3 = New Button
         .button4 = New Button
         .text1 = New TextBox
         .text2 = New TextBox
         .text3 = New TextBox

         .DateTimePicker1 = New DateTimePicker
         
         .Text = "Binding Sample"
         .ClientSize = New Size(450, 200)

         With .button1
            .Location = New Point(24, 16)
            .Size = New Size(64, 24)
            .Text = "<"
            AddHandler button1.click, AddressOf button1_Click
         End With
         
         
         With .button2
            .Location = New Point(90, 16)
            .Size = New Size(64, 24)
            .Text = ">"
            AddHandler button2.click, AddressOf button2_Click
         End With
         
         With .button3
            .Location = New Point(90, 100)
            .Size = New Size(64, 24)
            .Text = ">"
            AddHandler button3.click, AddressOf button3_Click
         End With

         With .button4
            .Location = New Point(150, 100)
            .Size = New Size(64, 24)
            .Text = ">"
            AddHandler button4.click, AddressOf button4_Click
         End With

         With .text1
            .Location = New Point(24, 50)
            .Size = New Size(150, 24)
         End With

         With .text2
            .Location = New Point(190, 50)
            .Size = New Size(150, 24)
         End With

         With .text3
            .Location = New Point(290, 150)
            .Size = New Size(150, 24)
         End With

            With .DateTimePicker1
               .Location = New Point(90, 150)
               .Size = New Size(200, 800)
            End With

            With .Controls
            .Add(button1)
            .Add(button2)
            .Add(button3)
            .Add(button4)
            .Add(text1)
            .Add(text2)
            .Add(text3)
            .Add(DateTimePicker1)
            End With
      End With
   End Sub
      
   Public Shared Sub Main
      Application.Run(new Form1)
   End Sub

   Private Sub SetUp
      ' Create a DataSet with two tables and one relation.
      MakeDataSet
      BindControls
   End Sub

   Private 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 
      ' TableName.ColumnName" string.

      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, AddressOf CurrencyStringToDecimal
      AddHandler b.Format, 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")
   End Sub

   Private Sub DecimalToCurrencyString(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".

      ' The application can only convert to string type. 
   
      If cevent.DesiredType IsNot GetType(String) Then
         Exit Sub
      End If 
   
      cevent.Value = CType(cevent.Value, decimal).ToString("c")
   End Sub

   Private Sub CurrencyStringToDecimal(sender As Object, cevent As 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 IsNot GetType(decimal) Then
         Exit Sub
      End If

      cevent.Value = Decimal.Parse(cevent.Value.ToString, _
      NumberStyles.Currency, nothing)
      
      ' 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)
   End Sub

   Private Sub button1_Click(sender As Object, e As System.EventArgs)
      ' Go to the previous item in the Customer list.
      bmCustomers.Position -= 1
   End Sub

   Private Sub button2_Click(sender As Object, e As System.EventArgs)
      ' Go to the next item in the Customer list.
      bmCustomers.Position += 1
   End Sub

   Private Sub button3_Click(sender As Object, e As System.EventArgs)
      ' Go to the previous item in the Order list.
      bmOrders.Position -= 1
   End Sub

   Private Sub button4_Click(sender As Object, e As System.EventArgs)
      ' Go to the next item in the Orders list.
      bmOrders.Position += 1
   End Sub

   ' Creates a DataSet with two tables and populates it.
   Private Sub MakeDataSet
      ' Create a DataSet.
      ds = New DataSet("myDataSet")

      ' Creates two DataTables.
      Dim tCust As DataTable = New DataTable("Customers")
      Dim tOrders As DataTable = New DataTable("Orders")

      ' Create two columns, and add them to the first table.
      Dim cCustID As DataColumn = New DataColumn("CustID", _
      System.Type.GetType("System.Int32"))
      Dim cCustName As DataColumn = New DataColumn("CustName")
      tCust.Columns.Add(cCustID)
      tCust.Columns.Add(cCustName)

      ' Create three columns, and add them to the second table.
      Dim cID As DataColumn = _
         New DataColumn("CustID", System.Type.GetType("System.Int32"))
      Dim cOrderDate As DataColumn = _
         New DataColumn("orderDate", System.Type.GetType("System.DateTime"))
      Dim cOrderAmount As DataColumn = _
         New DataColumn("OrderAmount", System.Type.GetType("System.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.
      Dim dr As DataRelation = New _
         DataRelation("custToOrders", cCustID, cID)
      ds.Relations.Add(dr)
      
      ' Populate the tables. For each customer and orders,
      ' create two DataRow variables.
      Dim newRow1 As DataRow
      Dim newRow2 As DataRow

         ' Create three customers in the Customers Table.
         Dim i As Integer
         For i = 1 to 3
            newRow1 = tCust.NewRow
            newRow1("custID") = i
            ' Adds the row to the Customers table.
            tCust.Rows.Add(newRow1)
         Next

         ' 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.
         Dim j As Integer
         For i = 1 to 3
         For j = 1 to 5
            newRow2 = tOrders.NewRow
            newRow2("CustID") = i
            newRow2("orderDate") = New DateTime(2001, i, j * 2)
            newRow2("OrderAmount") = i * 10 + j * .1
            ' Add the row to the Orders table.
            tOrders.Rows.Add(newRow2)
         Next
         Next
   End Sub
End Class

Comentarios

Utilice la clase Binding para crear y mantener un enlace sencillo entre la propiedad de un control y la propiedad de un objeto, o bien la propiedad del objeto actual en una lista de objetos.Use the Binding class to create and maintain a simple binding between the property of a control and either the property of an object, or the property of the current object in a list of objects.

Como ejemplo del primer caso, puede enlazar la propiedad Text de un control TextBox a la propiedad FirstName de un objeto Customer.As an example of the first case, you can bind the Text property of a TextBox control to the FirstName property of a Customer object. Como ejemplo del segundo caso, puede enlazar la propiedad Text de un control TextBox a la propiedad FirstName de un DataTable que contenga clientes.As an example of the second case, you can bind the Text property of a TextBox control to the FirstName property of a DataTable that contains customers.

La clase Binding también le permite dar formato a los valores para mostrarlos a través del evento Format y recuperar los valores con formato a través del evento Parse.The Binding class also enables you to format values for display through the Format event and to retrieve formatted values through the Parse event.

Al construir una instancia de Binding con el constructor Binding, debe especificar tres elementos:When constructing a Binding instance with Binding constructor, you must specify three items:

  • Nombre de la propiedad de control a la que se va a enlazar.The name of the control property to bind to.

  • Origen de datos.The data source.

  • La ruta de navegación que se resuelve como una lista o propiedad en el origen de datos.The navigation path that resolves to a list or property in the data source. La ruta de navegación también se usa para crear la propiedad BindingMemberInfo del objeto.The navigation path is also used to create the object's BindingMemberInfo property.

En primer lugar, debe especificar el nombre de la propiedad de control a la que desea enlazar los datos.First, you must specify name of the control property you want to bind the data to. Por ejemplo, para mostrar los datos en un control TextBox, especifique la propiedad Text.For example, to display data in a TextBox control, specify the Text property.

En segundo lugar, puede especificar una instancia de cualquiera de las clases de la tabla siguiente como origen de datos.Second, you can specify an instance of any one of the classes in the following table as the data source.

DescripciónDescription Ejemplo de C#C# example
Cualquier clase que implementa IBindingList o ITypedList.Any class that implements IBindingList or ITypedList. Entre ellas se incluyen las siguientes: DataSet, DataTable, DataView o DataViewManager.These include the following: DataSet, DataTable, DataView, or DataViewManager. DataSet ds = new DataSet("myDataSet");
Cualquier clase que implementa IList para crear una colección indizada de objetos.Any class that implements IList to create an indexed collection of objects. La colección se debe crear y rellenar antes de crear el Binding.The collection must be created and filled before creating the Binding. Los objetos de la lista deben ser del mismo tipo. de lo contrario, se producirá una excepción.The objects in the list must all be of the same type; otherwise, an exception will be thrown. ArrayList ar1 = new ArrayList; Customer1 cust1 = new Customer("Louis"); ar1.Add(cust1);
Un @no__t fuertemente tipado de objetos fuertemente tipadosA strongly typed IList of strongly typed objects Customer [] custList = new Customer[3];

En tercer lugar, debe especificar la ruta de navegación, que puede ser una cadena vacía (""), un nombre de propiedad único o una jerarquía de nombres delimitada por puntos.Third, you must specify the navigation path, which can be an empty string (""), a single property name, or a period-delimited hierarchy of names. Si establece la ruta de navegación en una cadena vacía, se llamará al método ToString en el objeto de origen de datos subyacente.If you set the navigation path to an empty string, the ToString method will be called on the underlying data source object.

Si el origen de datos es un DataTable, que puede contener varios objetos DataColumn, se debe usar la ruta de navegación para resolver en una columna específica.If the data source is a DataTable, which can contain multiple DataColumn objects, the navigation path must be used to resolve to a specific column.

Nota

Cuando el origen de datos es un DataSet, DataViewManager o @no__t 2, en realidad está enlazando a DataView.When the data source is a DataSet, DataViewManager, or DataTable, you are actually binding to a DataView. Por consiguiente, las filas enlazadas son realmente @no__t objetos-0.Consequently, the bound rows are actually DataRowView objects.

Se requiere una ruta de navegación delimitada por puntos cuando el origen de datos se establece en un objeto que contiene varios objetos DataTable (como un DataSet o DataViewManager).A period-delimited navigation path is required when the data source is set to an object that contains multiple DataTable objects (such as a DataSet or DataViewManager). También puede usar una ruta de navegación delimitada por puntos cuando se enlaza a un objeto cuyas propiedades devuelven referencias a otros objetos (por ejemplo, una clase con propiedades que devuelven otros objetos de clase).You can also use a period-delimited navigation path when you bind to an object whose properties return references to other objects (such as a class with properties that return other class objects). Por ejemplo, las siguientes rutas de navegación describen todos los campos de datos válidos:For example, the following navigation paths all describe valid data fields:

  • "Size. height""Size.Height"

  • "Suppliers. CompanyName""Suppliers.CompanyName"

  • "Regions. regionsToCustomers. CustomerFirstName""Regions.regionsToCustomers.CustomerFirstName"

  • "Regions. regionsToCustomers. customersToOrders. ordersToDetails. Quantity""Regions.regionsToCustomers.customersToOrders.ordersToDetails.Quantity"

Cada miembro de la ruta de acceso puede devolver una propiedad que se resuelve como un valor único (como un entero) o una lista de valores (como una matriz de cadenas).Each member of the path can return either a property that resolves to a single value (such as an integer), or a list of values (such as an array of strings). Aunque cada miembro de la ruta de acceso puede ser una lista o una propiedad, el miembro final debe resolverse como una propiedad.Although each member in the path can be a list or property, the final member must resolve to a property. Cada miembro se basa en el miembro anterior: "Size. height" se resuelve como la propiedad Height para el @no__t actual-1; "Regions. regionsToCustomers. CustomerFirstName" se resuelve como el nombre del cliente actual, donde el cliente es uno de los clientes de la región actual.Each member builds on the previous member: "Size.Height" resolves to the Height property for the current Size; "Regions.regionsToCustomers.CustomerFirstName" resolves to the first name for the current customer, where the customer is one of the customers for the current region.

Un DataRelation devuelve una lista de valores vinculando un DataTable a un segundo @no__t 2 en un DataSet.A DataRelation returns a list of values by linking one DataTable to a second DataTable in a DataSet. Si el DataSet contiene objetos DataRelation, puede especificar el miembro de datos como TableName seguido de un RelationName y, a continuación, un ColumnName.If the DataSet contains DataRelation objects, you can specify the data member as a TableName followed by a RelationName, and then a ColumnName. Por ejemplo, si el DataTable denominado "Suppliers" contiene un DataRelation denominado "suppliers2products", el miembro de datos podría ser "Suppliers. suppliers2products. ProductName".For example, if the DataTable named "Suppliers" contains a DataRelation named "suppliers2products", the data member could be "Suppliers.suppliers2products.ProductName".

El origen de datos puede constar de un conjunto de clases relacionadas.The data source can consist of a set of related classes. Por ejemplo, Imagine un conjunto de clases que cataloga sistemas solares.For example, imagine a set of classes that catalogs solar systems. La clase denominada System contiene una propiedad denominada Stars que devuelve una colección de objetos Star.The class named System contains a property named Stars that returns a collection of Star objects. Cada objeto Star tiene Name y Mass, así como una propiedad Planets que devuelve una colección de objetos Planet.Each Star object has Name and Mass properties, as well as a Planets property that returns a collection of Planet objects. En este sistema, cada planeta también tiene las propiedades Mass y Name.In this system, each planet also has Mass and Name properties. Cada objeto Planet tiene además una propiedad Moons que devuelve una colección de objetos Moon, cada uno de los cuales tiene también Name y Mass propiedades.Each Planet object further has a Moons property that returns a collection of Moon objects, each of which also has Name and Mass properties. Si especifica un objeto System como origen de datos, puede especificar cualquiera de los siguientes elementos como miembro de datos:If you specify a System object as the data source, you can specify any of the following as the data member:

  • "Stars.Name""Stars.Name"

  • "Estrellas. masa""Stars.Mass"

  • "Stars.Planets.Name""Stars.Planets.Name"

  • "Estrellas. planetas. masa""Stars.Planets.Mass"

  • "Stars.Planets.Moons.Name""Stars.Planets.Moons.Name"

  • "Estrellas. planetas. lunas. masa""Stars.Planets.Moons.Mass"

Los controles que pueden ser de enlace simple incluyen una colección de objetos Binding en un ControlBindingsCollection, al que se puede tener acceso a través de la propiedad DataBindings del control.Controls that can be simple-bound feature a collection of Binding objects in a ControlBindingsCollection, which you can access through the control's DataBindings property. Agregue un Binding a la colección llamando al método Add, enlazando así una propiedad del control a una propiedad de un objeto (o a una propiedad del objeto actual en una lista).You add a Binding to the collection by calling the Add method, thereby binding a property of the control to a property of an object (or to a property of the current object in a list).

Puede enlazar de forma sencilla a cualquier objeto que se derive de la clase System.Windows.Forms.Control, por ejemplo, los siguientes controles de Windows:You can simple-bind to any object that derives from the System.Windows.Forms.Control class, for example, the following Windows controls:

Nota

Solo la propiedad SelectedValue del control ComboBox, CheckedListBox y ListBox es un enlace simple.Only the SelectedValue property of the ComboBox, CheckedListBox, and ListBox control is simple bound.

La clase BindingManagerBase es una clase abstracta que administra todos los objetos Binding para un origen de datos y un miembro de datos determinados.The BindingManagerBase class is an abstract class that manages all the Binding objects for a particular data source and data member. Las clases que derivan de BindingManagerBase son las clases CurrencyManager y PropertyManager.Classes that derive from BindingManagerBase are the CurrencyManager and the PropertyManager classes. La forma en que se administra un Binding depende de si el Binding es un enlace de lista o un enlace de propiedad.How a Binding is managed depends on whether the Binding is a list binding or a property binding. Por ejemplo, si es un enlace de lista, puede usar el BindingManagerBase para especificar un Position en la lista. por lo tanto, el Position determina qué elemento (de todos los elementos de la lista) está enlazado realmente a un control.For example, if it is a list binding, you can use the BindingManagerBase to specify a Position in the list; the Position, therefore, determines which item (out of all items in the list) is actually bound to a control. Para devolver el @no__t adecuado, use el BindingContext.To return the appropriate BindingManagerBase, use the BindingContext.

Para agregar una nueva fila a un conjunto de controles enlazados al mismo DataSource, use el método AddNew de la clase BindingManagerBase.To add a new row to a set of controls bound to the same DataSource, use the AddNew method of the BindingManagerBase class. Use la propiedad Item[Object] de la clase BindingContext para devolver el @no__t 2 adecuado.Use the Item[Object] property of the BindingContext class to return the appropriate CurrencyManager. Para omitir la adición de la nueva fila, use el método CancelCurrentEdit.To escape the addition of the new row, use the CancelCurrentEdit method.

Constructores

Binding(String, Object, String)

Inicializa una nueva instancia de la clase Binding que establece un enlace sencillo entre la propiedad del control especificado y el miembro de datos especificado del origen de datos.Initializes a new instance of the Binding class that simple-binds the indicated control property to the specified data member of the data source.

Binding(String, Object, String, Boolean)

Inicializa una nueva instancia de la clase Binding que enlaza la propiedad del control indicada al miembro de datos especificado del origen de datos y, opcionalmente, permite aplicar formato.Initializes a new instance of the Binding class that binds the indicated control property to the specified data member of the data source, and optionally enables formatting to be applied.

Binding(String, Object, String, Boolean, DataSourceUpdateMode)

Inicializa una nueva instancia de la clase Binding que enlaza la propiedad del control especificada con el miembro de datos especificado del origen de datos indicado.Initializes a new instance of the Binding class that binds the specified control property to the specified data member of the specified data source. Habilita opcionalmente el formato y propaga valores al origen de datos basándose en la configuración de actualización especificada.Optionally enables formatting and propagates values to the data source based on the specified update setting.

Binding(String, Object, String, Boolean, DataSourceUpdateMode, Object)

Inicializa una nueva instancia de la clase Binding que enlaza la propiedad indicada del control con el miembro de datos especificado del origen de datos indicado.Initializes a new instance of the Binding class that binds the indicated control property to the specified data member of the specified data source. Habilita opcionalmente el formato, propaga valores al origen de datos basándose en la configuración de actualización especificada y establece la propiedad en el valor especificado cuando se devuelve DBNull desde el origen de datos.Optionally enables formatting, propagates values to the data source based on the specified update setting, and sets the property to the specified value when a DBNull is returned from the data source.

Binding(String, Object, String, Boolean, DataSourceUpdateMode, Object, String)

Inicializa una nueva instancia de la clase Binding que enlaza la propiedad del control especificada con el miembro de datos especificado del origen de datos indicado.Initializes a new instance of the Binding class that binds the specified control property to the specified data member of the specified data source. Opcionalmente, habilita el formato con la cadena de formato especificada, propaga valores al origen de datos según la configuración de actualización especificada y establece la propiedad en el valor especificado cuando se devuelve DBNull desde el origen de datos.Optionally enables formatting with the specified format string; propagates values to the data source based on the specified update setting; and sets the property to the specified value when a DBNull is returned from the data source.

Binding(String, Object, String, Boolean, DataSourceUpdateMode, Object, String, IFormatProvider)

Inicializa una nueva instancia de la clase Binding con la propiedad del control especificada en el miembro de datos especificado del origen de datos indicado.Initializes a new instance of the Binding class with the specified control property to the specified data member of the specified data source. Habilita opcionalmente el formato con la cadena de formato especificada, propaga valores al origen de datos según la configuración de actualización especificada, habilita el formato con la cadena de formato especificada, establece la propiedad en el valor especificado cuando se devuelve DBNull desde el origen de datos y establece el proveedor de formato especificado.Optionally enables formatting with the specified format string; propagates values to the data source based on the specified update setting; enables formatting with the specified format string; sets the property to the specified value when a DBNull is returned from the data source; and sets the specified format provider.

Propiedades

BindableComponent

Obtiene el control al que está asociado Binding.Gets the control the Binding is associated with.

BindingManagerBase

Obtiene el objeto BindingManagerBase para este objeto Binding.Gets the BindingManagerBase for this Binding.

BindingMemberInfo

Obtiene un objeto que contiene información sobre este enlace de acuerdo con el parámetro dataMember del constructor Binding.Gets an object that contains information about this binding based on the dataMember parameter in the Binding constructor.

Control

Obtiene el control al que pertenece el enlace.Gets the control that the binding belongs to.

ControlUpdateMode

Obtiene o establece cuándo se propagan los cambios en el origen de datos a la propiedad del control enlazado.Gets or sets when changes to the data source are propagated to the bound control property.

DataSource

Obtiene el origen de datos para este enlace.Gets the data source for this binding.

DataSourceNullValue

Obtiene o establece el valor que se almacenará en el origen de datos si el valor del control es null o está vacío.Gets or sets the value to be stored in the data source if the control value is null or empty.

DataSourceUpdateMode

Obtiene o establece un valor que indica cuándo se propagan al origen de datos los cambios en la propiedad del control enlazado.Gets or sets a value that indicates when changes to the bound control property are propagated to the data source.

FormatInfo

Obtiene o establece IFormatProvider que proporciona el comportamiento de formato personalizado.Gets or sets the IFormatProvider that provides custom formatting behavior.

FormatString

Obtiene o establece los caracteres especificadores de formato que indican cómo se va a mostrar un valor.Gets or sets the format specifier characters that indicate how a value is to be displayed.

FormattingEnabled

Obtiene o establece un valor que indica si se aplicará formato y conversión de tipos a los datos de la propiedad del control.Gets or sets a value indicating whether type conversion and formatting is applied to the control property data.

IsBinding

Obtiene un valor que indica si el enlace está activo.Gets a value indicating whether the binding is active.

NullValue

Obtiene o establece el Object que se establecerá como la propiedad del control cuando el origen de datos contenga un valor DBNull.Gets or sets the Object to be set as the control property when the data source contains a DBNull value.

PropertyName

Obtiene el nombre de la propiedad con enlace a datos del control.Gets the name of the control's data-bound property.

Métodos

Equals(Object)

Determina si el objeto especificado es igual al objeto actual.Determines whether the specified object is equal to the current object.

(Heredado de Object)
GetHashCode()

Sirve como función hash predeterminada.Serves as the default hash function.

(Heredado de Object)
GetType()

Obtiene el Type de la instancia actual.Gets the Type of the current instance.

(Heredado de Object)
MemberwiseClone()

Crea una copia superficial del Object actual.Creates a shallow copy of the current Object.

(Heredado de Object)
OnBindingComplete(BindingCompleteEventArgs)

Genera el evento BindingComplete.Raises the BindingComplete event.

OnFormat(ConvertEventArgs)

Genera el evento Format.Raises the Format event.

OnParse(ConvertEventArgs)

Genera el evento Parse.Raises the Parse event.

ReadValue()

Establece la propiedad del control en el valor leído del origen de datos.Sets the control property to the value read from the data source.

ToString()

Devuelve un valor de tipo string que representa el objeto actual.Returns a string that represents the current object.

(Heredado de Object)
WriteValue()

Lee el valor actual de la propiedad del control y lo escribe en el origen de datos.Reads the current value from the control property and writes it to the data source.

Eventos

BindingComplete

Se produce cuando la propiedad FormattingEnabled está establecida en true y se ha completado una operación de enlace, como cuando se insertan datos del control en el origen de datos o viceversa.Occurs when the FormattingEnabled property is set to true and a binding operation is complete, such as when data is pushed from the control to the data source or vice versa.

Format

Se produce cuando la propiedad de un control está enlazada a un valor de datos.Occurs when the property of a control is bound to a data value.

Parse

Se produce cuando cambia el valor de un control con enlace a datos.Occurs when the value of a data-bound control changes.

Se aplica a

Consulte también: