BindingExpression Class

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Contains information about a single binding within a Binding object.

Inheritance Hierarchy

System..::.Object
System.Windows..::.Expression
System.Windows.Data..::.BindingExpressionBase
System.Windows.Data..::.BindingExpression

Namespace: System.Windows.Data
Assembly: System.Windows (in System.Windows.dll)

Syntax

Public NotInheritable Class BindingExpression _
    Inherits BindingExpressionBase
public sealed class BindingExpression : BindingExpressionBase

The BindingExpression type exposes the following members.

Properties

Name Description
DataItem Gets the binding source object that this BindingExpression uses.
ParentBinding Returns the Binding object of the current BindingExpression.

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Methods

Name Description
Equals(Object) Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Finalize Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
GetHashCode Serves as a hash function for a particular type. (Inherited from Object.)
GetType Gets the Type of the current instance. (Inherited from Object.)
MemberwiseClone Creates a shallow copy of the current Object. (Inherited from Object.)
ToString Returns a string that represents the current object. (Inherited from Object.)
UpdateSource Sends the current binding target value to the binding source property in TwoWay bindings.

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Remarks

A Binding object can be used by multiple binding targets. The BindingExpression class, however, represents a single binding. You can retrieve a BindingExpression instance from a binding target by calling its FrameworkElement..::.GetBindingExpression method. You can then use the BindingExpression to call the UpdateSource method. This is useful to control when values are copied from the binding target to the binding source. For more information, see Data binding for Windows Phone 8.

Examples

The following code example demonstrates how to use this method.

<TextBox x:Name="textBox1" Text="{Binding Test, Mode=TwoWay, UpdateSourceTrigger=Explicit}" />
<Button Content="Update" Click="Button_Click" />
Public Class TestData
    Private testValue As String
    Public Property Test() As String
        Get
            Return testValue
        End Get
        Set(ByVal value As String)
            testValue = value
        End Set
    End Property
End Class

Private data As TestData

Public Sub New()

    InitializeComponent()

    data = New TestData
    With data
        .Test = "one"
    End With

    textBox1.DataContext = data

End Sub

Private Sub Button_Click(ByVal sender As Object, _
    ByVal e As RoutedEventArgs)

    Dim expression As BindingExpression = _
        textBox1.GetBindingExpression(TextBox.TextProperty)
    MessageBox.Show("Before UpdateSource, Test = " & data.Test)
    expression.UpdateSource()
    MessageBox.Show("After UpdateSource, Test = " & data.Test)

End Sub
public class TestData
{
    public String Test { get; set; }
}

TestData data;

public MainPage()
{
    InitializeComponent();
    data = new TestData { Test = "one" };
    textBox1.DataContext = data;
}

private void Button_Click(object sender, RoutedEventArgs e)
{
    BindingExpression expression = textBox1.GetBindingExpression(TextBox.TextProperty);
    MessageBox.Show("Before UpdateSource, Test = " + data.Test);
    expression.UpdateSource();
    MessageBox.Show("After UpdateSource, Test = " + data.Test);
}

Version Information

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Platforms

Windows Phone

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.

See Also

Reference

System.Windows.Data Namespace

FrameworkElement..::.GetBindingExpression

Binding

Other Resources

Data binding for Windows Phone 8