Binding Class
Represents the simple binding between the property value of an object and the property value of a control.
For a list of all members of this type, see Binding Members.
System.Object
System.Windows.Forms.Binding
[Visual Basic] Public Class Binding [C#] public class Binding [C++] public __gc class Binding [JScript] public class Binding
Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Remarks
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.
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. As an example of the second case, you can bind the Text property of a TextBox control to the FirstName property of a DataTable containing customers.
The Binding class also enables you to format values for display through the Format event and to retrieve formatted values through the Parse event.
When constructing a Binding instance with the Binding contructor, you must specify three items: the name of the control property to bind to, the data source, and the navigation path that resolves to a list or property in the data source. The navigation path is also used to create the object's BindingMemberInfo.
First, you must specify name of the control property you want to bind the data to. For example, to display data in a TextBox control, specify the Text property. Second, you can specify an instance of any of the following classes as the data source:
| Description | Example |
|---|---|
| Any class that implements IBindingList or ITypedList. These include: DataSet, DataTable, DataView, or DataViewManager. | A C# example:
DataSet ds = new DataSet("myDataSet"); |
| Any class that implements IList to create an indexed collection of objects. The collection must be created and filled before creating the Binding object. The objects in the list must all be of the same type; otherwise an exception will be thrown. | A C# example:
ArrayList ar1 = new ArrayList; Customer1 cust1 = new Customer("Louis"); ar1.Add(cust1); |
| Strongly typed IList of strongly typed objects | A C# example:
Customer [] custList = new Customer[3]; |
Third, you must specify the navigation path, which can be an empty string (""), a single property name, or a period-delimited hierarchy of names. If you set the navigation path to an empty string, the ToString method will be called on the underlying data source object.
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.
Note When the data source is a DataSet, DataViewManager, or DataTable, you are actually binding to a DataView. Consequently, the bound rows are actually DataRowView objects.
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). 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). For example, the following navigation paths all describe valid data fields:
- "Size.Height"
- "Suppliers.CompanyName"
- "Regions.regionsToCustomers.CustomerFirstName"
- "Regions.regionsToCustomers.customersToOrders.ordersToDetails.Quantity"
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). Although each member in the path can be a list or property, the final member must resolve to a property. Each member builds on the previous member: "Size.Height" resolves to the Height 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.
A DataRelation returns a list of values by linking one DataTable to a second DataTable in a DataSet. If the DataSet contains DataRelation objects, you can specify the data member as a TableName followed by a RelationName, and then a ColumnName. For example, if the DataTable named "Suppliers" contains a DataRelation named "suppliers2products", the data member could be "Suppliers.suppliers2products.ProductName".
The data source can consist of a set of related classes. For example, imagine a set of classes that catalogs solar systems. The class named System contains a property named Stars that returns a collection of star objects. Each Star object has Name and Mass properties, as well as a Planets property that returns a collection of Planet objects. In this system, each planet also has Mass and Name properties. Each Planet object further has a Moons property that returns a collection of Moon objects, each of which also has Name and Mass properties. If you specify a System object as the data source, you can specify any of the following as the data member:
- "Stars.Name"
- "Stars.Mass"
- "Stars.Planets.Name"
- "Stars.Planets.Mass"
- "Stars.Planets.Moons.Name"
- "Stars.Planets.Moons.Mass"
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. You add a Binding object 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).
You can simple-bind to any object that derives from the System.Windows.Forms.Control class, for example, the following Windows controls:
- Button
- CheckBox
- CheckedListBox
- ComboBox
- DateTimePicker
- DomainUpDown
- GroupBox
- HScrollBar
- Label
- LinkLabel
- ListBox
- ListView
- MonthCalendar
- NumericUpDown
- PictureBox
- ProgressBar
- RadioButton
- RichTextBox
- ScrollBar
- StatusBar
- TextBox
- TreeView
- VScrollBar
Note Only the SelectedValue property of the ComboBox, CheckedListBox, and ListBox control is simple bound.
The BindingManagerBase class is an abstract class that manages all the Binding objects for a particular data source and data member. Classes that derive from BindingManagerBase are the CurrencyManager and the PropertyManager classes. How a Binding is managed depends on whether the Binding is a list binding or a property binding. For example, if it is a list binding, you can use the BindingManagerBase object 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. To return the appropriate BindingManagerBase, use the BindingContext.
To add a new row to a set of controls bound to the same DataSource, use the AddNew method of the BindingManagerBase class. Use the Item property of the BindingContext class to return the appropriate CurrencyManager. To escape the addition of the new row, use the CancelCurrentEdit method.
Example
The following example creates a Windows Form with several controls that demonstrate simple data binding. The example creates a DataSet with two tables named Customers and Orders, and a DataRelation named custToOrders. Four controls (a DateTimePicker and three TextBox controls) are data bound to columns in the tables. For each control, the example creates and adds a Binding to the control through the DataBindings property. The example returns a BindingManagerBase object for each table through the form's BindingContext object. Four Button controls increment or decrement the Position property on the BindingManagerBase objects.
[Visual Basic] Imports System 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 Not (components Is 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 .AutoScaleBaseSize = New Size(5, 13) .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 Not cevent.DesiredType Is 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 Not cevent.DesiredType Is 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 Protected Sub button1_Click(sender As Object, e As System.EventArgs) ' Go to the previous item in the Customer list. bmCustomers.Position -= 1 End Sub Protected Sub button2_Click(sender As Object, e As System.EventArgs) ' Go to the next item in the Customer list. bmCustomers.Position += 1 End Sub Protected Sub button3_Click(sender As Object, e As System.EventArgs) ' Go to the previous item in the Order list. bmOrders.Position -= 1 End Sub Protected 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 [C#] 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.AutoScaleBaseSize = new System.Drawing.Size(5, 13); 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); } protected void button1_Click(object sender, System.EventArgs e) { // Go to the previous item in the Customer list. bmCustomers.Position -= 1; } protected void button2_Click(object sender, System.EventArgs e) { // Go to the next item in the Customer list. bmCustomers.Position += 1; } protected void button3_Click(object sender, System.EventArgs e) { // Go to the previous item in the Orders list. bmOrders.Position-=1; } protected 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); } } } } [C++] [JScript] import System; import System.Data; import System.Drawing; import System.Globalization; import System.Windows.Forms; public class Form1 extends System.Windows.Forms.Form { private var components : System.ComponentModel.Container; private var button1 : Button; private var button2 : Button; private var button3 : Button; private var button4 : Button; private var text1 : TextBox; private var text2 : TextBox; private var text3 : TextBox; private var bmCustomers : BindingManagerBase; private var bmOrders : BindingManagerBase; private var ds : DataSet; private var DateTimePicker1 : DateTimePicker; public function Form1() { // Required for Windows Form Designer support. InitializeComponent(); // Call SetUp to bind the controls. SetUp(); } private function 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.AutoScaleBaseSize = new System.Drawing.Size(5, 13); 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.add_Click(button1_Click); button2.Location = new System.Drawing.Point(90, 16); button2.Size = new System.Drawing.Size(64, 24); button2.Text = ">"; button2.add_Click(button2_Click); button3.Location = new System.Drawing.Point(90, 100); button3.Size = new System.Drawing.Size(64, 24); button3.Text = "<"; button3.add_Click(button3_Click); button4.Location = new System.Drawing.Point(150, 100); button4.Size = new System.Drawing.Size(64, 24); button4.Text = ">"; button4.add_Click(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 function Dispose(disposing : boolean){ if( disposing ){ if (components != null){ components.Dispose();} } super.Dispose( disposing ); } public static function Main() { Application.Run(new Form1()); } private function SetUp() { // Create a DataSet with two tables and one relation. MakeDataSet(); BindControls(); } protected function 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. */ var b : Binding = new Binding ("Text", ds, "customers.custToOrders.OrderAmount"); b.add_Parse(CurrencyStringToDecimal); b.add_Format(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 function DecimalToCurrencyString(sender, cevent : 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 != String.GetType()) return; cevent.Value = (Decimal(cevent.Value)).ToString("c"); } private function CurrencyStringToDecimal(sender, cevent : 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 != Decimal.GetType()) 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); } protected function button1_Click(sender, e : System.EventArgs) { // Go to the previous item in the Customer list. bmCustomers.Position -= 1; } protected function button2_Click(sender, e : System.EventArgs) { // Go to the next item in the Customer list. bmCustomers.Position += 1; } protected function button3_Click(sender, e : System.EventArgs) { // Go to the previous item in the Orders list. bmOrders.Position-=1; } protected function button4_Click(sender, e : System.EventArgs) { // Go to the next item in the Orders list. bmOrders.Position+=1; } // Create a DataSet with two tables and populate it. private function MakeDataSet() { // Create a DataSet. ds = new DataSet("myDataSet"); // Create two DataTables. var tCust : DataTable = new DataTable("Customers"); var tOrders : DataTable= new DataTable("Orders"); // Create two columns, and add them to the first table. var cCustID : DataColumn = new DataColumn("CustID", Int32); var cCustName : DataColumn = new DataColumn("CustName"); tCust.Columns.Add(cCustID); tCust.Columns.Add(cCustName); // Create three columns, and add them to the second table. var cID : DataColumn = new DataColumn("CustID", Int32); var cOrderDate : DataColumn = new DataColumn("orderDate", DateTime); var cOrderAmount : DataColumn = new DataColumn("OrderAmount", 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. var dr : DataRelation = new DataRelation ("custToOrders", cCustID , cID); ds.Relations.Add(dr); /* Populate the tables. For each customer and order, create two DataRow variables. */ var newRow1 : DataRow; var newRow2 : DataRow; // Create three customers in the Customers Table. for(var i : int = 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(var j : int = 1; j < 4; j++) { for(var k : int = 1; k < 6; k++) { newRow2 = tOrders.NewRow(); newRow2["CustID"]= j; newRow2["orderDate"]= new DateTime(2001, j, k * 2); newRow2["OrderAmount"] = j * 10 + k * .1; // Add the row to the Orders table. tOrders.Rows.Add(newRow2); } } } }
Requirements
Namespace: System.Windows.Forms
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
See Also
Binding Members | System.Windows.Forms Namespace | BindingContext | BindingManagerBase | ComboBox | DataGrid