Binding Klasse

Definition

public ref class Binding

[System.ComponentModel.TypeConverter(typeof(System.Windows.Forms.ListBindingConverter))]
public class Binding

[<System.ComponentModel.TypeConverter(typeof(System.Windows.Forms.ListBindingConverter))>]
type Binding = class

Public Class Binding

Vererbung

Object

Binding

Attribute

TypeConverterAttribute

Beispiele

Im folgenden Codebeispiel wird ein Windows Form mit mehreren Steuerelementen erstellt, die eine einfache Datenbindung veranschaulichen. Im Beispiel wird ein DataSet mit zwei Tabellen mit dem Namen Customers und Ordersund einem DataRelation mit dem Namen custToOrderserstellt. Vier Steuerelemente (ein DateTimePicker und drei TextBox Steuerelemente) sind Daten, die an Spalten in den Tabellen gebunden sind. Für jedes Steuerelement wird im Beispiel ein Binding erstellt und dem Steuerelement über die DataBindings -Eigenschaft hinzugefügt. Im Beispiel wird ein BindingManagerBase für jede Tabelle über das Formular BindingContextzurückgegeben. Vier Button Steuerelemente erhöhen oder dekrementieren die Position -Eigenschaft für die BindingManagerBase -Objekte.

#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

Hinweise

Verwenden Sie die Binding -Klasse, um eine einfache Bindung zwischen der Eigenschaft eines Steuerelements und entweder der -Eigenschaft eines -Objekts oder der -Eigenschaft des aktuellen Objekts in einer Liste von -Objekten zu erstellen und zu verwalten.

Als Beispiel für den ersten Fall können Sie die Text Eigenschaft eines TextBox Steuerelements an die FirstName -Eigenschaft eines Customer -Objekts binden. Als Beispiel für den zweiten Fall können Sie die Text Eigenschaft eines TextBox Steuerelements an die Eigenschaft eines DataTable -Steuerelements binden, das FirstName Kunden enthält.

Die Binding -Klasse ermöglicht es Ihnen auch, Werte für die Anzeige durch das Format Ereignis zu formatieren und formatierte Werte über das Parse Ereignis abzurufen.

Beim Erstellen eines Binding instance mit Binding Konstruktor müssen Sie drei Elemente angeben:

• Der Name der Steuerelementeigenschaft, an die gebunden werden soll.

• Die Datenquelle.

• Der Navigationspfad, der in eine Liste oder Eigenschaft in der Datenquelle aufgelöst wird. Der Navigationspfad wird auch verwendet, um die Eigenschaft des BindingMemberInfo Objekts zu erstellen.

Zunächst müssen Sie den Namen der Steuerelementeigenschaft angeben, an die Sie die Daten binden möchten. Geben Sie beispielsweise die Text -Eigenschaft an, um Daten in einem TextBox Steuerelement anzuzeigen.

Zweitens können Sie einen instance einer der Klassen in der folgenden Tabelle als Datenquelle angeben.

Drittens müssen Sie den Navigationspfad angeben, der eine leere Zeichenfolge (""), ein einzelner Eigenschaftsname oder eine durch Perioden getrennte Hierarchie von Namen sein kann. Wenn Sie den Navigationspfad auf eine leere Zeichenfolge festlegen, wird die ToString Methode für das zugrunde liegende Datenquellenobjekt aufgerufen.

Wenn die Datenquelle eine DataTableist, die mehrere DataColumn Objekte enthalten kann, muss der Navigationspfad verwendet werden, um in eine bestimmte Spalte aufzulösen.

Ein periodentrennter Navigationspfad ist erforderlich, wenn die Datenquelle auf ein Objekt festgelegt ist, das mehrere DataTable Objekte enthält (z. B. ein DataSet oder DataViewManager). Sie können auch einen durch Perioden getrennten Navigationspfad verwenden, wenn Sie an ein Objekt binden, dessen Eigenschaften Verweise auf andere Objekte zurückgeben (z. B. eine Klasse mit Eigenschaften, die andere Klassenobjekte zurückgeben). Die folgenden Navigationspfade beschreiben beispielsweise gültige Datenfelder:

• "Size.Height"

• "Suppliers.CompanyName"

• "Regions.regionsToCustomers.CustomerFirstName"

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

Jedes Element des Pfads kann entweder eine Eigenschaft zurückgeben, die in einen einzelnen Wert (z. B. eine ganze Zahl) aufgelöst wird, oder eine Liste von Werten (z. B. ein Array von Zeichenfolgen). Obwohl jedes Element im Pfad eine Liste oder Eigenschaft sein kann, muss das endgültige Element in eine Eigenschaft aufgelöst werden. Jedes Element baut auf dem vorherigen Member auf: "Size.Height" wird in die Height -Eigenschaft für das aktuelle Sizeaufgelöst. "Regions.regionsToCustomers.CustomerFirstName" wird in den Vornamen des aktuellen Kunden aufgelöst, wobei der Kunde einer der Kunden für die aktuelle Region ist.

Ein DataRelation gibt eine Liste von Werten zurück, indem eins DataTable mit einer Sekunde DataTable in einem DataSetverknüpft wird. Wenn das DataSet -Objekt enthält DataRelation , können Sie den Datenmember als gefolgt TableName von einem RelationNameund dann als angeben ColumnName. Wenn beispielsweise der DataTable benannte "Suppliers" den DataRelation Namen "suppliers2products" enthält, könnte das Datenelement "Suppliers.suppliers2products.ProductName" sein.

Die Datenquelle kann aus einer Reihe verwandter Klassen bestehen. Stellen Sie sich beispielsweise eine Reihe von Klassen vor, die Solarsysteme katalogisieren. Die Klasse mit dem Namen System enthält eine Eigenschaft namens Stars , die eine Auflistung von Star Objekten zurückgibt. Jedes Star Objekt verfügt über Name Eigenschaften und Mass sowie über eine Planets Eigenschaft, die eine Auflistung von Planet -Objekten zurückgibt. In diesem System hat Mass jeder Planet auch Eigenschaften und Name . Jedes Planet Objekt verfügt darüber hinaus über eine Moons -Eigenschaft, die eine Auflistung von Moon -Objekten zurückgibt, die jeweils auch Eigenschaften und Mass hatName. Wenn Sie ein System Objekt als Datenquelle angeben, können Sie einen der folgenden Elemente als Datenmember angeben:

• "Stars.Name"

• "Stars.Mass"

• "Stars.Planets.Name"

• "Stars.Planets.Mass"

• "Stars.Planets.Moons.Name"

• "Stars.Planets.Moons.Mass"

Steuerelemente, die einfach gebunden sein können, enthalten eine Auflistung von Binding Objekten in einem ControlBindingsCollection, auf die Sie über die -Eigenschaft des Steuerelements DataBindings zugreifen können. Sie fügen der Auflistung eine Binding hinzu, indem Sie die Add -Methode aufrufen und dadurch eine Eigenschaft des Steuerelements an eine -Eigenschaft eines -Objekts (oder an eine Eigenschaft des aktuellen Objekts in einer Liste) binden.

Sie können einfach an jedes Objekt binden, das von der System.Windows.Forms.Control -Klasse abgeleitet ist, z. B. die folgenden Windows-Steuerelemente:

• Button

• CheckBox

• CheckedListBox

• ComboBox

• DateTimePicker

• DomainUpDown

• GroupBox

• HScrollBar

• Label

• LinkLabel

• ListBox

• ListView

• MonthCalendar

• NumericUpDown

• PictureBox

• ProgressBar

• RadioButton

• RichTextBox

• ScrollBar

• StatusBar

• TextBox

• TreeView

• VScrollBar

Die BindingManagerBase -Klasse ist eine abstrakte Klasse, die Binding alle Objekte für eine bestimmte Datenquelle und einen bestimmten Datenmember verwaltet. Von abgeleitete BindingManagerBase Klassen sind die CurrencyManager - und die PropertyManager -Klasse. Wie ein Binding verwaltet wird, hängt davon ab, ob es sich bei um Binding eine Listenbindung oder eine Eigenschaftsbindung handelt. Wenn es sich z. B. um eine Listenbindung handelt, können Sie den BindingManagerBase verwenden, um ein Position in der Liste anzugeben. Daher bestimmt , Positionwelches Element (von allen Elementen in der Liste) tatsächlich an ein Steuerelement gebunden ist. Um die entsprechenden BindingManagerBasezurückzugeben, verwenden Sie die BindingContext.

Verwenden Sie die AddNew -Methode BindingManagerBase der -Klasse, um einer Reihe von Steuerelementen, die an dasselbe DataSourcegebunden sind, eine neue Zeile hinzuzufügen. Verwenden Sie die Item[] -Eigenschaft der BindingContext -Klasse, um den entsprechenden CurrencyManagerzurückzugeben. Verwenden Sie CancelCurrentEdit die -Methode, um das Hinzufügen der neuen Zeile zu escapen.

Konstruktoren

Eigenschaften

Methoden

Ereignisse

Gilt für:

Weitere Informationen

• BindingContext
• BindingManagerBase
• ComboBox
• DataGrid