BindingMode Enum
Definition
Important
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The direction of changes propagation for bindings.
public enum class BindingModepublic enum BindingModetype BindingMode = Public Enum BindingMode- Inheritance
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BindingMode
Fields
| Name | Value | Description |
|---|---|---|
| Default | 0 | When used in Bindings, indicates that the Binding should use the DefaultBindingMode. When used in BindableProperty declaration, defaults to BindingMode.OneWay. |
| TwoWay | 1 | Indicates that the binding should propagates changes from source (usually the View Model) to target (the BindableObject) in both directions. |
| OneWay | 2 | Indicates that the binding should only propagate changes from source (usually the View Model) to target (the BindableObject). This is the default mode for most BindableProperty values. |
| OneWayToSource | 3 | Indicates that the binding should only propagate changes from target (the BindableObject) to source (usually the View Model). This is mainly used for read-only BindableProperty values. |
| OneTime | 4 | Indicates that the binding will be applied only when the binding context changes and the value will not be monitored for changes with |
Remarks
The following examples shows some BindingMode use cases.
public class PersonViewModel
{
public string Name { get; set; }
public string Company { get; set; }
}
Label label;
PersonViewModel viewmodel;
//BindingMode.OneWay
label = new Label ();
label.BindingContext = viewmodel = new PersonViewModel ();
label.SetBinding<PersonViewModel> (Label.TextProperty, vm => vm.Name, mode: BindingMode.OneWay);
viewmodel.Name = "John Doe";
Debug.WriteLine (label.Text); //prints ""
label.Text = "Foo";
Debug.WriteLine (viewmodel.Name); //prints "John Doe"
//BindingMode.TwoWay
label = new Label ();
label.BindingContext = viewmodel = new PersonViewModel ();
label.SetBinding<PersonViewModel> (Label.TextProperty, vm => vm.Name, mode: BindingMode.TwoWay);
viewmodel.Name = "John Doe";
Debug.WriteLine (label.Text); //prints "John Doe"
label.Text = "Foo";
Debug.WriteLine (viewmodel.Name); //prints "Foo"
//BindingMode.OneWayToSource
label = new Label ();
label.BindingContext = viewmodel = new PersonViewModel ();
label.SetBinding<PersonViewModel> (Label.TextProperty, vm => vm.Name, mode: BindingMode.OneWayToSource);
viewmodel.Name = "John Doe";
Debug.WriteLine (label.Text); //prints ""
label.Text = "Foo";
Debug.WriteLine (viewmodel.Name); //prints "Foo"
