Binding.Mode Property (System.Windows.Data)

Mode Property

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This page is specific to

Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

Binding..::.Mode Property

Gets or sets a value that indicates the direction of the data flow in the binding.

Namespace: System.Windows.Data
Assembly: PresentationFramework (in PresentationFramework.dll)
XMLNS for XAML: http://schemas.microsoft.com/winfx/2006/xaml/presentation, http://schemas.microsoft.com/netfx/2007/xaml/presentation

Syntax

Visual Basic (Declaration)

Public Property Mode As BindingMode

Visual Basic (Usage)

Dim instance As Binding
Dim value As BindingMode

value = instance.Mode

instance.Mode = value

public BindingMode Mode { get; set; }

Visual C++

public:
property BindingMode Mode {
    BindingMode get ();
    void set (BindingMode value);
}

JScript

public function get Mode () : BindingMode
public function set Mode (value : BindingMode)

XAML Attribute Usage

<object Mode="BindingMode" .../>

Property Value

Type: System.Windows.Data..::.BindingMode
One of the BindingMode values. The default is Default, which returns the default binding mode value of the target dependency property. However, the default value varies for each dependency property. In general, user-editable control properties, such as those of text boxes and check boxes, default to two-way bindings, whereas most other properties default to one-way bindings.
A programmatic way to determine whether a dependency property binds one-way or two-way by default is to get the property metadata of the property using GetMetadata and then check the Boolean value of the BindsTwoWayByDefault property.

Remarks

To support OneWay and TwoWay bindings, the underlying data must implement INotifyPropertyChanged. For details, see How to: Implement Property Change Notification.

For TwoWay or OneWayToSource bindings, you can control the target-to-source updates by setting the UpdateSourceTrigger property. For more information, see UpdateSourceTrigger.

For more information on the different binding modes, see Data Binding Overview.

Examples

This example shows how to specify whether the binding updates only the binding target (target) property, the binding source (source) property, or both the target property and the source property.

You use the Mode property to specify the direction of the binding. The following enumeration list shows the available options for binding updates:

TwoWay updates the target property or the property whenever either the target property or the source property changes.
OneWay updates the target property only when the source property changes.
OneTime updates the target property only when the application starts or when the DataContext undergoes a change.
OneWayToSource updates the source property when the target property changes.
Default causes the default Mode value of target property to be used.

For more information, see the BindingMode enumeration.

The following example shows how to set the Mode property. For the complete sample, see Controlling the Direction and Timing of the Data Flow Sample.

XAML

<TextBlock Name="IncomeText" Grid.Row="0" Grid.Column="1"
  Text="{Binding Path=TotalIncome, Mode=OneTime}"/>

To detect source changes (applicable to OneWay and TwoWay bindings), the source must implement a suitable property change notification mechanism such as INotifyPropertyChanged. See How to: Implement Property Change Notification for an example of an INotifyPropertyChanged implementation.

For TwoWay or OneWayToSource bindings, you can control the timing of the source updates by setting the UpdateSourceTrigger property. See UpdateSourceTrigger for more information.

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Version Information

.NET Framework

Supported in: 3.5, 3.0

Reference

Binding Class

Binding Members

System.Windows.Data Namespace

Other Resources

Data Binding Overview