Binding class

Applies to Windows and Windows Phone

Defines a binding that connects the properties of binding targets and data sources.

Inheritance

Object
  DependencyObject
    BindingBase
      Binding

Syntax


public class Binding : BindingBase


<dependencyobject dependencyproperty="{Binding bindingArgs}" />

XAML Values

bindingArgs

Arguments for a {Binding} markup extension usage. The {Binding} usage can include an implicit Path value, and/or one or more propertyname=value pairs that set properties of the Binding class. All read-write properties of the Binding class can be set through a {Binding} markup extension usage, although some require additional markup extensions for their values. For more info on this syntax, and string syntax for each argument, see Binding markup extension. If the existing DataContext provides enough binding info, you can use "{Binding}" with no arguments.

Attributes

[MarshalingBehavior(Agile)]
[Threading(Both)]
[Version(0x06020000)]
[WebHostHidden()]

Members

The Binding class has these types of members:

Constructors

The Binding class has these constructors.

ConstructorDescription
Binding Initializes a new instance of the Binding class.

 

Methods

The Binding class has these methods. It also inherits methods from the Object class.

MethodDescription
ClearValue Clears the local value of a dependency property. (Inherited from DependencyObject)
GetAnimationBaseValue Returns any base value established for a dependency property, which would apply in cases where an animation is not active. (Inherited from DependencyObject)
GetValue Returns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject)
ReadLocalValue Returns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject)
SetValue Sets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject)

 

Properties

The Binding class has these properties.

PropertyAccess typeDescription

Converter

Read/writeGets or sets the converter object that is called by the binding engine to modify the data as it is passed between the source and target, or vice versa.

ConverterLanguage

Read/writeGets or sets a value that names the language to pass to any converter specified by the Converter property.

ConverterParameter

Read/writeGets or sets a parameter that can be used in the Converter logic.

Dispatcher

Read-onlyGets the CoreDispatcher that this object is associated with. (Inherited from DependencyObject)

ElementName

Read/writeGets or sets the name of the element to use as the binding source for the Binding.

FallbackValue

Read/writeGets or sets the value to use when the binding is unable to return a value.

Mode

Read/writeGets or sets a value that indicates the direction of the data flow in the binding.

Path

Read/writeGets or sets the path to the binding source property.

RelativeSource

Read/writeGets or sets the binding source by specifying its location relative to the position of the binding target. This is most often used in bindings within XAML control templates.

Source

Read/writeGets or sets the data source for the binding.

TargetNullValue

Read/writeGets or sets the value that is used in the target when the value of the source is null.

UpdateSourceTrigger

Read/writeGets or sets a value that determines the timing of binding source updates for two-way bindings.

 

Remarks

The Binding markup extension enables you to specify a Binding value as a single attribute string in XAML, including setting Binding properties such as Path and Source. For more info about data binding concepts, see Data binding overview.

The Binding class might be considered the code-behind exposure of the Binding markup extension. If a binding is already applied to a target (which happens when the XAML is loaded), you can't set the read-write properties of a Binding object to change how a binding behaves at run-time. Any XAML-defined binding should be considered immutable. But you can create a new Binding object, set its properties, and establish a new binding on a specific UI element target using FrameworkElement.SetBinding. For more info, see the Creating bindings in code section of Data binding overview.

A Binding object connects a dependency property of a FrameworkElement directly to a data object so that updates to the data object are automatically propagated to the property that uses data binding. The Binding class defines the properties of a binding. Each binding must have a target element, target property, and data source, although some values are provided by default if you don't specify them.

To bind to a property or a sub-property on a data object, set the Path property of the Binding object. For more info on how to set Path in code or in XAML, see Property-path syntax or Binding markup extension.

You can apply an instance of a Binding class to multiple targets. However, you cannot modify the property values of a Binding object after you attach it to a target element.

Note  Calling the FrameworkElement.SetBinding method and passing in a new Binding object won't necessarily remove an existing binding. Instead, you should use the DependencyObject.ClearValue method.

For more info on XAML attribute usage for properties that can take a Binding, or that can otherwise be set to a data-bound value, see Binding markup extension.

The property that is the target of a data binding must be a dependency property. For more info, see Dependency properties overview.

Examples

The following code example demonstrates how to create a binding in XAML. For the complete code listing, see the XAML data binding sample.


<StackPanel Margin="5">

  <TextBlock Text="Name:" Style="{StaticResource DescriptionTextStyle}" 
    Margin="5" HorizontalAlignment="Left" VerticalAlignment="Top"/>

  <TextBox Text="{Binding Path=Name, Mode=TwoWay}" 
    Width="350" Margin="5" HorizontalAlignment="Left" VerticalAlignment="Top"/>

  <TextBlock Text="Organization:" Style="{StaticResource DescriptionTextStyle}" 
    Margin="5" HorizontalAlignment="Left" VerticalAlignment="Top"/>

  <!-- You can omit the 'Path=' portion of the binding expression. --> 
  <TextBox Text="{Binding Organization, Mode=TwoWay}" Width="350" 
    Margin="5" HorizontalAlignment="Left" VerticalAlignment="Top"/>

</StackPanel>

The following example code demonstrates how to create a binding in code.


// Create the source string.
string s = "Hello";

// Create the binding description.
Binding b = new Binding();
b.Mode = BindingMode.OneTime;
b.Source = s;

// Attach the binding to the target.
MyText.SetBinding(TextBlock.TextProperty, b);


Requirements

Minimum supported client

Windows 8 [Windows Store apps only]

Minimum supported server

Windows Server 2012 [Windows Store apps only]

Minimum supported phone

Windows Phone 8.1 [Windows Runtime apps only]

Namespace

Windows.UI.Xaml.Data
Windows::UI::Xaml::Data [C++]

Metadata

Windows.winmd

See also

XAML data binding sample
Data binding overview
Dependency properties overview
Property-path syntax
BindingOperations.SetBinding

 

 

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