Binding Binding Binding Binding Class

Definição

Representa a associação simples entre o valor da propriedade de um objeto e o valor da propriedade de um controle.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
Herança
BindingBindingBindingBinding
Atributos

Exemplos

O exemplo de código a seguir cria um formulário do Windows com vários controles que demonstram a vinculação de dados simples.The following code example creates a Windows Form with several controls that demonstrate simple data binding. O exemplo cria um DataSet com duas tabelas chamadas Customers e Orders, e um DataRelation nome custToOrders.The example creates a DataSet with two tables named Customers and Orders, and a DataRelation named custToOrders. Quatro controles (a DateTimePicker e três TextBox controles) são dados associados a colunas nas tabelas.Four controls (a DateTimePicker and three TextBox controls) are data bound to columns in the tables. Para cada controle, o exemplo cria e adiciona um Binding ao controle por meio da DataBindings propriedade.For each control, the example creates and adds a Binding to the control through the DataBindings property. O exemplo retorna um BindingManagerBase para cada tabela por meio do BindingContextformulário.The example returns a BindingManagerBase for each table through the form's BindingContext. Quatro Button controles incrementam ou decrementam a Position propriedade BindingManagerBase nos objetos.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

Comentários

Use a Binding classe para criar e manter uma associação simples entre a propriedade de um controle e a propriedade de um objeto ou a propriedade do objeto atual em uma 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 um exemplo do primeiro caso, Text você pode associar a propriedade de um TextBox controle à FirstName propriedade de um Customer objeto.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 um exemplo do segundo caso, Text você pode associar a propriedade de um TextBox controle à FirstName propriedade de um DataTable que contém 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.

A Binding classe também permite formatar valores para exibição por meio do Format evento e recuperar valores formatados por meio do Parse evento.The Binding class also enables you to format values for display through the Format event and to retrieve formatted values through the Parse event.

Ao construir uma instância Binding com Binding o construtor, você deve especificar três itens:When constructing a Binding instance with Binding constructor, you must specify three items:

  • O nome da propriedade de controle à qual associar.The name of the control property to bind to.

  • A fonte de dados.The data source.

  • O caminho de navegação que é resolvido para uma lista ou propriedade na fonte de dados.The navigation path that resolves to a list or property in the data source. O caminho de navegação também é usado para criar a propriedade BindingMemberInfo do objeto.The navigation path is also used to create the object's BindingMemberInfo property.

Primeiro, você deve especificar o nome da propriedade de controle à qual deseja associar os dados.First, you must specify name of the control property you want to bind the data to. Por exemplo, para exibir dados em um TextBox controle, especifique a Text propriedade.For example, to display data in a TextBox control, specify the Text property.

Em segundo lugar, você pode especificar uma instância de qualquer uma das classes na tabela a seguir como a fonte de dados.Second, you can specify an instance of any one of the classes in the following table as the data source.

DescriçãoDescription Exemplo do C#C# example
Qualquer classe que IBindingList implemente ITypedListou.Any class that implements IBindingList or ITypedList. Isso inclui o seguinte: DataSet, DataTable, DataViewou DataViewManager.These include the following: DataSet, DataTable, DataView, or DataViewManager. DataSet ds = new DataSet("myDataSet");
Qualquer classe que implementa IList para criar uma coleção indexada de objetos.Any class that implements IList to create an indexed collection of objects. A coleção deve ser criada e preenchida antes da Bindingcriação do.The collection must be created and filled before creating the Binding. Os objetos na lista devem ser do mesmo tipo; caso contrário, uma exceção será lançada.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);
Um tipo fortemente IList tipado de objetos fortemente tipadosA strongly typed IList of strongly typed objects Customer [] custList = new Customer[3];

Terceiro, você deve especificar o caminho de navegação, que pode ser uma cadeia de caracteres vazia (""), um único nome de propriedade ou uma hierarquia de nomes delimitada por ponto.Third, you must specify the navigation path, which can be an empty string (""), a single property name, or a period-delimited hierarchy of names. Se você definir o caminho de navegação como uma cadeia de caracteres ToString vazia, o método será chamado no objeto de fonte de dados subjacente.If you set the navigation path to an empty string, the ToString method will be called on the underlying data source object.

Se a fonte de dados for DataTableum, que pode conter DataColumn vários objetos, o caminho de navegação deverá ser usado para resolver para uma coluna 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.

Observação

Quando a fonte de dados é DataSetuma DataViewManager, ou DataTable, você está realmente ligando a um DataView.When the data source is a DataSet, DataViewManager, or DataTable, you are actually binding to a DataView. Consequentemente, as linhas associadas são DataRowView , na verdade, objetos.Consequently, the bound rows are actually DataRowView objects.

Um caminho de navegação delimitado por ponto é necessário quando a fonte de dados é definida como um objeto que DataTable contém vários objetos (como DataSet um DataViewManagerou).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). Você também pode usar um caminho de navegação delimitado por ponto ao associar a um objeto cujas propriedades retornam referências a outros objetos (como uma classe com propriedades que retornam outros objetos de classe).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 exemplo, os seguintes caminhos de navegação descrevem os campos de dados válidos:For example, the following navigation paths all describe valid data fields:

  • "Tamanho. altura""Size.Height"

  • "Suppliers.CompanyName""Suppliers.CompanyName"

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

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

Cada membro do caminho pode retornar uma propriedade que seja resolvida para um único valor (como um inteiro) ou uma lista de valores (como uma matriz de cadeias de caracteres).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). Embora cada membro no caminho possa ser uma lista ou propriedade, o membro final deve ser resolvido para uma propriedade.Although each member in the path can be a list or property, the final member must resolve to a property. Cada membro se baseia no membro anterior: O "tamanho. altura" é resolvido para a Height Propriedade do atual; Size "Regiões. regionsToCustomers. CustomerFirstName" resolve para o primeiro nome do cliente atual, onde o cliente é um dos clientes da região atual.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.

Um DataRelation retorna uma lista de valores vinculando um DataTable a um segundo DataTable em um DataSet.A DataRelation returns a list of values by linking one DataTable to a second DataTable in a DataSet. Se o DataSet contiver DataRelation objetos, você poderá especificar o membro de dados TableName como um seguido RelationNamepor um e, ColumnNameem seguida, um.If the DataSet contains DataRelation objects, you can specify the data member as a TableName followed by a RelationName, and then a ColumnName. Por exemplo, se o DataTable nome "Suppliers" contiver um DataRelation chamado "suppliers2products", o membro de dados poderá ser "Suppliers. suppliers2products. ProductName".For example, if the DataTable named "Suppliers" contains a DataRelation named "suppliers2products", the data member could be "Suppliers.suppliers2products.ProductName".

A fonte de dados pode consistir em um conjunto de classes relacionadas.The data source can consist of a set of related classes. Por exemplo, imagine um conjunto de classes que cataloga sistemas solares.For example, imagine a set of classes that catalogs solar systems. A classe denominada System contém uma propriedade Stars chamada que retorna uma coleção Star de objetos.The class named System contains a property named Stars that returns a collection of Star objects. Cada Star objeto tem Name propriedades Mass e, bem como uma Planets propriedade que retorna uma coleção de Planet objetos.Each Star object has Name and Mass properties, as well as a Planets property that returns a collection of Planet objects. Neste sistema, cada planeta também tem Mass Propriedades e. NameIn this system, each planet also has Mass and Name properties. Cada Planet objeto tem mais uma Moons propriedade que retorna uma coleção de Moon objetos, cada um deles também tem Name propriedades Mass e.Each Planet object further has a Moons property that returns a collection of Moon objects, each of which also has Name and Mass properties. Se você especificar um System objeto como a fonte de dados, poderá especificar qualquer um dos seguintes como o membro de dados: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"

  • "Estrelas. massa""Stars.Mass"

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

  • "Stars.Planets.Mass""Stars.Planets.Mass"

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

  • "Stars.Planets.Moons.Mass""Stars.Planets.Moons.Mass"

Controles que podem ser associados simples apresentam uma coleção de Binding objetos em um ControlBindingsCollection, que você pode acessar por meio da Propriedade do DataBindings controle.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. Você adiciona um Binding à coleção chamando o Add método, associando assim uma propriedade do controle a uma propriedade de um objeto (ou a uma propriedade do objeto atual em uma 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).

Você pode fazer a ligação simples com qualquer objeto derivado da System.Windows.Forms.Control classe, por exemplo, os seguintes controles do Windows:You can simple-bind to any object that derives from the System.Windows.Forms.Control class, for example, the following Windows controls:

Observação

Somente a SelectedValue ComboBoxPropriedade do controle, CheckedListBoxe ListBox é vinculada simples.Only the SelectedValue property of the ComboBox, CheckedListBox, and ListBox control is simple bound.

A BindingManagerBase classe é uma classe abstrata que gerencia Binding todos os objetos para uma fonte de dados e um membro de dados específicos.The BindingManagerBase class is an abstract class that manages all the Binding objects for a particular data source and data member. Classes que derivam BindingManagerBase de são CurrencyManager as PropertyManager classes e.Classes that derive from BindingManagerBase are the CurrencyManager and the PropertyManager classes. A maneira Binding como um é gerenciado depende se Binding o é uma associação de lista ou de propriedade.How a Binding is managed depends on whether the Binding is a list binding or a property binding. Por exemplo, se for uma associação de lista, você poderá usar o BindingManagerBase para especificar um Position na lista; o Position, portanto, determina qual item (fora de todos os itens na lista) está realmente associado a um controle.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 retornar o apropriado BindingManagerBase, use o BindingContext.To return the appropriate BindingManagerBase, use the BindingContext.

Para adicionar uma nova linha a um conjunto de controles vinculados ao mesmo DataSource, use o AddNew método da BindingManagerBase classe.To add a new row to a set of controls bound to the same DataSource, use the AddNew method of the BindingManagerBase class. Use a Item[Object] propriedade BindingContext da classe para retornar o apropriado CurrencyManager.Use the Item[Object] property of the BindingContext class to return the appropriate CurrencyManager. Para escapar da adição da nova linha, use o CancelCurrentEdit método.To escape the addition of the new row, use the CancelCurrentEdit method.

Construtores

Binding(String, Object, String) Binding(String, Object, String) Binding(String, Object, String) Binding(String, Object, String)

Inicializa uma nova instância da classe Binding que gera uma associação simples entre a propriedade do controle indicada e o membro de dados da fonte de dados especificado.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) Binding(String, Object, String, Boolean) Binding(String, Object, String, Boolean) Binding(String, Object, String, Boolean)

Inicializa uma nova instância da classe Binding que associa a propriedade de controle indicada ao membro de dados especificado da fonte de dados e, opcionalmente, permite que a formatação seja aplicada.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) Binding(String, Object, String, Boolean, DataSourceUpdateMode) Binding(String, Object, String, Boolean, DataSourceUpdateMode) Binding(String, Object, String, Boolean, DataSourceUpdateMode)

Inicializa uma nova instância da classe Binding que associa a propriedade do controle indicada ao membro de dados da fonte de dados especificado.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, permite formatar e propaga valores para a fonte de dados com base na configuração de atualização especificada.Optionally enables formatting and propagates values to the data source based on the specified update setting.

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

Inicializa uma nova instância da classe Binding que associa a propriedade do controle indicada ao membro de dados da fonte de dados especificado.Initializes a new instance of the Binding class that binds the indicated control property to the specified data member of the specified data source. Opcionalmente, habilita a formatação, propaga valores para a fonte de dados com base na configuração de atualização especificada e define a propriedade para o valor especificado quando um DBNull é retornado de uma fonte de dados.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) Binding(String, Object, String, Boolean, DataSourceUpdateMode, Object, String) Binding(String, Object, String, Boolean, DataSourceUpdateMode, Object, String) Binding(String, Object, String, Boolean, DataSourceUpdateMode, Object, String)

Inicializa uma nova instância da classe Binding que associa a propriedade do controle indicada ao membro de dados da fonte de dados especificado.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 a formatação com a cadeia de caracteres de formato especificada, propaga valores para a fonte de dados com base na configuração de atualização especificada e define a propriedade para o valor especificado quando um DBNull é retornado de uma fonte de dados.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) Binding(String, Object, String, Boolean, DataSourceUpdateMode, Object, String, IFormatProvider) Binding(String, Object, String, Boolean, DataSourceUpdateMode, Object, String, IFormatProvider) Binding(String, Object, String, Boolean, DataSourceUpdateMode, Object, String, IFormatProvider)

Inicializa uma nova instância da classe Binding com a propriedade do controle especificada para o membro de dados especificado da fonte de dados especificada.Initializes a new instance of the Binding class with the specified control property to the specified data member of the specified data source. Opcionalmente, permite a formatação com a cadeia de formato especificada; propaga valores para a fonte de dados de acordo com a configuração de atualização especificada; permite a formatação com a cadeia de formato especificada; define a propriedade com o valor especificado quando um DBNull é retornado da fonte de dados e define o provedor 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.

Propriedades

BindableComponent BindableComponent BindableComponent BindableComponent

Obtém o controle ao qual o Binding está associado.Gets the control the Binding is associated with.

BindingManagerBase BindingManagerBase BindingManagerBase BindingManagerBase

Obtém o BindingManagerBase para este Binding.Gets the BindingManagerBase for this Binding.

BindingMemberInfo BindingMemberInfo BindingMemberInfo BindingMemberInfo

Obtém um objeto que contém informações sobre esta associação com base no parâmetro dataMember no construtor Binding.Gets an object that contains information about this binding based on the dataMember parameter in the Binding constructor.

Control Control Control Control

Obtém o controle ao qual a associação pertence.Gets the control that the binding belongs to.

ControlUpdateMode ControlUpdateMode ControlUpdateMode ControlUpdateMode

Obtém ou define quando as alterações na fonte de dados são propagadas para a propriedade do controle associado.Gets or sets when changes to the data source are propagated to the bound control property.

DataSource DataSource DataSource DataSource

Obtém a fonte de dados desta associação.Gets the data source for this binding.

DataSourceNullValue DataSourceNullValue DataSourceNullValue DataSourceNullValue

Obtém ou define o valor a ser armazenado na fonte de dados se o valor do controle é null ou vazio.Gets or sets the value to be stored in the data source if the control value is null or empty.

DataSourceUpdateMode DataSourceUpdateMode DataSourceUpdateMode DataSourceUpdateMode

Obtém ou define um valor que indica quando as alterações da propriedade do controle associado são propagadas para a fonte de dados.Gets or sets a value that indicates when changes to the bound control property are propagated to the data source.

FormatInfo FormatInfo FormatInfo FormatInfo

Obtém ou define o IFormatProvider que fornece o comportamento da formatação personalizada.Gets or sets the IFormatProvider that provides custom formatting behavior.

FormatString FormatString FormatString FormatString

Obtém ou define os caracteres especificadores de formato que indicam como um valor deve ser exibido.Gets or sets the format specifier characters that indicate how a value is to be displayed.

FormattingEnabled FormattingEnabled FormattingEnabled FormattingEnabled

Obtém ou define um valor que indica se a formatação e conversão de tipo é aplicada a dados de propriedade de controle.Gets or sets a value indicating whether type conversion and formatting is applied to the control property data.

IsBinding IsBinding IsBinding IsBinding

Obtém um valor que indica se a associação está ativa.Gets a value indicating whether the binding is active.

NullValue NullValue NullValue NullValue

Obtém ou define o Object a ser definido como a propriedade de controle quando a fonte de dados contém um valor DBNull.Gets or sets the Object to be set as the control property when the data source contains a DBNull value.

PropertyName PropertyName PropertyName PropertyName

Obtém o nome da propriedade associada a dados do controle.Gets the name of the control's data-bound property.

Métodos

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Determina se o objeto especificado é igual ao objeto atual.Determines whether the specified object is equal to the current object.

(Inherited from Object)
GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Serve como a função de hash padrão.Serves as the default hash function.

(Inherited from Object)
GetType() GetType() GetType() GetType()

Obtém o Type da instância atual.Gets the Type of the current instance.

(Inherited from Object)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Cria uma cópia superficial do Object atual.Creates a shallow copy of the current Object.

(Inherited from Object)
OnBindingComplete(BindingCompleteEventArgs) OnBindingComplete(BindingCompleteEventArgs) OnBindingComplete(BindingCompleteEventArgs) OnBindingComplete(BindingCompleteEventArgs)

Aciona o evento BindingComplete.Raises the BindingComplete event.

OnFormat(ConvertEventArgs) OnFormat(ConvertEventArgs) OnFormat(ConvertEventArgs) OnFormat(ConvertEventArgs)

Aciona o evento Format.Raises the Format event.

OnParse(ConvertEventArgs) OnParse(ConvertEventArgs) OnParse(ConvertEventArgs) OnParse(ConvertEventArgs)

Aciona o evento Parse.Raises the Parse event.

ReadValue() ReadValue() ReadValue() ReadValue()

Define a propriedade de controle com o valor lido da fonte de dados.Sets the control property to the value read from the data source.

ToString() ToString() ToString() ToString()

Retorna uma cadeia de caracteres que representa o objeto atual.Returns a string that represents the current object.

(Inherited from Object)
WriteValue() WriteValue() WriteValue() WriteValue()

Lê o valor atual da propriedade de controle e o grava na fonte de dados.Reads the current value from the control property and writes it to the data source.

Eventos

BindingComplete BindingComplete BindingComplete BindingComplete

Ocorre quando a propriedade FormattingEnabled está definida como true e uma operação de associação é concluída, como quando os dados são retirados do controle para a fonte de dados ou vice-versaOccurs 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 Format Format Format

Ocorre quando a propriedade de um controle é associada a um valor de dados.Occurs when the property of a control is bound to a data value.

Parse Parse Parse Parse

Ocorre quando o valor de um controle de limite de dados é alterado.Occurs when the value of a data-bound control changes.

Aplica-se a

Veja também