Binding 类

定义

代表某对象属性值和某控件属性值之间的简单绑定。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
继承
Binding
属性

示例

下面的代码示例创建一个 Windows 窗体,其中包含多个演示简单数据绑定的控件。The following code example creates a Windows Form with several controls that demonstrate simple data binding. 该示例创建一个 @no__t 0,其中包含两个名为 CustomersOrders 的表以及一个名为 custToOrders 的 @no__t 3。The example creates a DataSet with two tables named Customers and Orders, and a DataRelation named custToOrders. 四个控件(一 @no__t 0 和三个 @no__t 控件)是绑定到表中的列的数据。Four controls (a DateTimePicker and three TextBox controls) are data bound to columns in the tables. 对于每个控件,该示例通过 @no__t 属性创建 @no__t,并将其添加到控件中。For each control, the example creates and adds a Binding to the control through the DataBindings property. 该示例通过窗体的 @no__t 为每个表返回一个 @no__t 0。The example returns a BindingManagerBase for each table through the form's BindingContext. Button 控件递增或递减 @no__t 2 个对象上的 @no__t 属性。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

注解

使用 Binding 类来创建和维护控件的属性和对象的属性之间的简单绑定,或对象列表中当前对象的属性。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.

作为第一种情况的示例,可以将 @no__t 控件的 Text 属性绑定到 @no__t 3 对象的 FirstName 属性。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. 作为第二种情况的示例,您可以将 @no__t 控件的 Text 属性绑定到包含客户的 @no__t 3 的 FirstName 属性。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.

通过 Binding 类,还可以设置值的格式,以便在 @no__t 1 事件中显示,并通过 @no__t 的事件检索格式化的值。The Binding class also enables you to format values for display through the Format event and to retrieve formatted values through the Parse event.

使用 @no__t 构造函数构造 Binding 实例时,必须指定三个项:When constructing a Binding instance with Binding constructor, you must specify three items:

  • 要绑定到的控件属性的名称。The name of the control property to bind to.

  • 数据源。The data source.

  • 解析为数据源中的列表或属性的导航路径。The navigation path that resolves to a list or property in the data source. 导航路径还用于创建对象的 @no__t 0 属性。The navigation path is also used to create the object's BindingMemberInfo property.

首先,必须指定要将数据绑定到的控件属性的名称。First, you must specify name of the control property you want to bind the data to. 例如,若要在 TextBox 控件中显示数据,请指定 @no__t 属性。For example, to display data in a TextBox control, specify the Text property.

其次,您可以指定下表中的任何一个类的实例作为数据源。Second, you can specify an instance of any one of the classes in the following table as the data source.

说明Description C# 示例C# example
任何实现 IBindingListITypedList 的类。Any class that implements IBindingList or ITypedList. 其中包括以下内容: DataSetDataTableDataView 或 @no__t 为3。These include the following: DataSet, DataTable, DataView, or DataViewManager. DataSet ds = new DataSet("myDataSet");
任何实现 IList 的类创建对象的索引集合。Any class that implements IList to create an indexed collection of objects. 创建 @no__t 之前,必须先创建并填充集合。The collection must be created and filled before creating the Binding. 列表中的对象必须具有相同的类型;否则,将引发异常。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);
强类型对象的强类型 @no__t 0A strongly typed IList of strongly typed objects Customer [] custList = new Customer[3];

第三,您必须指定导航路径,该路径可以是空字符串("")、单个属性名或用句点分隔的名称的层次结构。Third, you must specify the navigation path, which can be an empty string (""), a single property name, or a period-delimited hierarchy of names. 如果将导航路径设置为空字符串,则将对基础数据源对象调用 ToString 方法。If you set the navigation path to an empty string, the ToString method will be called on the underlying data source object.

如果数据源是 DataTable,它可以包含多个 @no__t 1 对象,则必须使用导航路径来解析特定列。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.

备注

当数据源为 DataSet、@no__t 为-1 或 DataTable 时,实际上将绑定到 @no__t 3。When the data source is a DataSet, DataViewManager, or DataTable, you are actually binding to a DataView. 因此,绑定行实际上是 @no__t 0 个对象。Consequently, the bound rows are actually DataRowView objects.

当数据源设置为包含多个 @no__t 0 对象(如 @no__t 1 或 DataViewManager)的对象时,需要用句点分隔的导航路径。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). 绑定到属性返回对其他对象的引用的对象(例如具有返回其他类对象的属性的类)时,还可以使用句点分隔的导航路径。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). 例如,以下导航路径都描述了有效的数据字段:For example, the following navigation paths all describe valid data fields:

  • "大小高度""Size.Height"

  • "Suppliers.CompanyName""Suppliers.CompanyName"

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

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

路径的每个成员都可以返回解析为单个值的属性(例如整数)或值的列表(例如字符串数组)。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). 尽管路径中的每个成员都可以是列表或属性,但最终成员必须解析为属性。Although each member in the path can be a list or property, the final member must resolve to a property. 每个成员都建立在上一个成员之上:"Size,Height" 解析为当前 @no__t 的 @no__t 值为-1;"RegionsToCustomers. CustomerFirstName" 解析为当前客户的名字,其中客户是当前区域的客户之一。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.

@No__t 返回值的列表,方法是将一 DataTable 链接到 @no__t 中的第二 DataTableA DataRelation returns a list of values by linking one DataTable to a second DataTable in a DataSet. 如果 DataSet 包含 @no__t 1 个对象,则可以将数据成员指定为 TableName 后跟 RelationName,然后指定 @no__t。If the DataSet contains DataRelation objects, you can specify the data member as a TableName followed by a RelationName, and then a ColumnName. 例如,如果名为 "suppliers2products" 的 @no__t 0 包含名为 "" 的 @no__t 1,则该数据成员可以是 "suppliers2products"。For example, if the DataTable named "Suppliers" contains a DataRelation named "suppliers2products", the data member could be "Suppliers.suppliers2products.ProductName".

数据源可以包含一组相关的类。The data source can consist of a set of related classes. 例如,假设有一组目录为太阳系的类。For example, imagine a set of classes that catalogs solar systems. 名为 System 的类包含一个名为 @no__t 的属性,该属性返回 @no__t 2 个对象的集合。The class named System contains a property named Stars that returns a collection of Star objects. 每个 @no__t 0 对象具有 @no__t 和 @no__t 2 属性,以及一个返回 Planet 个对象集合的 @no__t 3 属性。Each Star object has Name and Mass properties, as well as a Planets property that returns a collection of Planet objects. 在此系统中,每个行星还具有 MassName 属性。In this system, each planet also has Mass and Name properties. 每个 @no__t 0 对象都有一个 @no__t 属性,该属性返回 @no__t 2 个对象的集合,其中每个对象还具有 @no__t 和 @no__t 属性。Each Planet object further has a Moons property that returns a collection of Moon objects, each of which also has Name and Mass properties. 如果将 @no__t 0 对象指定为数据源,则可以指定以下任意项作为数据成员: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"

  • "Stars.Mass""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"

可以是简单绑定功能的控件是 ControlBindingsCollection 中 @no__t 0 对象的集合,您可以通过控件的 DataBindings 属性访问这些对象。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. 可以通过调用 Add 方法向集合添加 Binding,从而将控件的属性绑定到对象的属性(或列表中当前对象的属性)。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).

您可以简单地绑定到从 @no__t 0 类派生的任何对象,例如以下 Windows 控件:You can simple-bind to any object that derives from the System.Windows.Forms.Control class, for example, the following Windows controls:

备注

仅 @no__t 的 ComboBox、@no__t 和 @no__t 3 控件的属性为简单绑定。Only the SelectedValue property of the ComboBox, CheckedListBox, and ListBox control is simple bound.

@No__t-0 类是一个抽象类,用于管理特定数据源和数据成员的所有 @no__t 1 对象。The BindingManagerBase class is an abstract class that manages all the Binding objects for a particular data source and data member. 派生自 BindingManagerBase 的类是 CurrencyManager 和 @no__t 2 类。Classes that derive from BindingManagerBase are the CurrencyManager and the PropertyManager classes. @No__t-0 的管理方式取决于 @no__t 为列表绑定还是属性绑定。How a Binding is managed depends on whether the Binding is a list binding or a property binding. 例如,如果它是列表绑定,则可以使用 BindingManagerBase 来指定列表中的 @no__t;因此,@no__t 会确定哪个项(列表中的所有项中的所有项)实际上已绑定到控件。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. 若要返回适当的 BindingManagerBase,请使用 @no__t。To return the appropriate BindingManagerBase, use the BindingContext.

若要将新行添加到绑定到同一个 DataSource 的一组控件,请使用第 2 @no__t 类的 @no__t 方法。To add a new row to a set of controls bound to the same DataSource, use the AddNew method of the BindingManagerBase class. 使用 @no__t 1 类的 Item[Object] 属性返回相应的 CurrencyManagerUse the Item[Object] property of the BindingContext class to return the appropriate CurrencyManager. 若要对新行进行转义,请使用 CancelCurrentEdit 方法。To escape the addition of the new row, use the CancelCurrentEdit method.

构造函数

Binding(String, Object, String)

初始化 Binding 类的一个新实例,该类将指示的控件属性简单绑定到数据源的指定数据成员。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)

初始化 Binding 类的一个新实例,该实例将指示的控件属性绑定到数据源的指定数据成员,并启用要应用的格式设置(可选)。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)

初始化 Binding 类的新实例,该实例将指定的控件属性绑定到指定数据源的指定数据成员。Initializes a new instance of the Binding class that binds the specified control property to the specified data member of the specified data source. (可选)根据指定的更新设置,启用格式设置并将值传播到数据源。Optionally enables formatting and propagates values to the data source based on the specified update setting.

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

初始化 Binding 类的新实例,该实例将指示的控件属性绑定到指定数据源的指定数据成员。Initializes a new instance of the Binding class that binds the indicated control property to the specified data member of the specified data source. (可选)根据指定的更新设置,启用格式设置并将值传播到数据源,然后在从数据源返回 DBNull 时将该属性设置为指定值。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)

初始化 Binding 类的新实例,该实例将指定的控件属性绑定到指定数据源的指定数据成员。Initializes a new instance of the Binding class that binds the specified control property to the specified data member of the specified data source. (可选)允许用指定的格式字符串进行格式设置;根据指定的更新设置将值传播到数据源;在从数据源返回 DBNull 时将该属性设置为指定的值。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)

初始化 Binding 类的新实例,并将指定的控件属性绑定到指定数据源的指定数据成员。Initializes a new instance of the Binding class with the specified control property to the specified data member of the specified data source. (可选)利用指定的格式字符串启用格式设置;根据指定的更新设置将值传播到数据源;利用指定的格式字符串启用格式设置;以及当从数据源返回 DBNull 时将属性设为指定值,并设置指定的格式提供程序。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.

属性

BindableComponent

获取与 Binding 关联的控件。Gets the control the Binding is associated with.

BindingManagerBase

获取此 BindingManagerBaseBindingGets the BindingManagerBase for this Binding.

BindingMemberInfo

获取包含有关该绑定的信息的对象(基于 Binding 构造函数中的 dataMember 参数)。Gets an object that contains information about this binding based on the dataMember parameter in the Binding constructor.

Control

获取绑定所属的控件。Gets the control that the binding belongs to.

ControlUpdateMode

获取或设置将数据源的更改传播到绑定控件属性的时间。Gets or sets when changes to the data source are propagated to the bound control property.

DataSource

获取该绑定的数据源。Gets the data source for this binding.

DataSourceNullValue

获取或设置将存储在数据源中的值(如果控件值为 null 或为空)。Gets or sets the value to be stored in the data source if the control value is null or empty.

DataSourceUpdateMode

获取或设置一个值,该值指示将绑定控件属性的更改传播到数据源的时间。Gets or sets a value that indicates when changes to the bound control property are propagated to the data source.

FormatInfo

获取或设置提供自定义格式设置行为的 IFormatProviderGets or sets the IFormatProvider that provides custom formatting behavior.

FormatString

获取或设置指示如何显示值的格式说明符。Gets or sets the format specifier characters that indicate how a value is to be displayed.

FormattingEnabled

获取或设置一个值,该值指示是否对控件属性数据应用类型转换和格式设置。Gets or sets a value indicating whether type conversion and formatting is applied to the control property data.

IsBinding

获取指示绑定是否活动的值。Gets a value indicating whether the binding is active.

NullValue

获取或设置当数据源包含 Object 值时,作为控件属性设置的 DBNullGets or sets the Object to be set as the control property when the data source contains a DBNull value.

PropertyName

获取控件的数据绑定属性的名称。Gets the name of the control's data-bound property.

方法

Equals(Object)

确定指定的对象是否等于当前对象。Determines whether the specified object is equal to the current object.

(继承自 Object)
GetHashCode()

作为默认哈希函数。Serves as the default hash function.

(继承自 Object)
GetType()

获取当前实例的 TypeGets the Type of the current instance.

(继承自 Object)
MemberwiseClone()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

(继承自 Object)
OnBindingComplete(BindingCompleteEventArgs)

引发 BindingComplete 事件。Raises the BindingComplete event.

OnFormat(ConvertEventArgs)

引发 Format 事件。Raises the Format event.

OnParse(ConvertEventArgs)

引发 Parse 事件。Raises the Parse event.

ReadValue()

将控件属性设置为从数据源读取的值。Sets the control property to the value read from the data source.

ToString()

返回表示当前对象的字符串。Returns a string that represents the current object.

(继承自 Object)
WriteValue()

读取控件属性的当前值并将其写入数据源。Reads the current value from the control property and writes it to the data source.

事件

BindingComplete

FormattingEnabled 属性设置为 true 且完成绑定操作(如将数据从控件推到数据源或与之相反的操作)时发生。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

当将某控件的属性绑定到某个数据值时发生。Occurs when the property of a control is bound to a data value.

Parse

在数据绑定控件的值更改时发生。Occurs when the value of a data-bound control changes.

适用于

另请参阅