Qt Reference Documentation

QML Binding Element

The Binding element allows arbitrary property bindings to be created. More...

This element was introduced in Qt 4.7.


Detailed Description

Sometimes it is necessary to bind to a property of an object that wasn't directly instantiated by QML - generally a property of a class exported to QML by C++. In these cases, regular property binding doesn't work. Binding allows you to bind any value to any property.

For example, imagine a C++ application that maps an "app.enteredText" property into QML. You could use Binding to update the enteredText property like this.

 TextEdit { id: myTextField; text: "Please type here..." }
 Binding { target: app; property: "enteredText"; value: myTextField.text }

Whenever the text in the TextEdit is updated, the C++ property will be updated also.

If the binding target or binding property is changed, the bound value is immediately pushed onto the new target.

See also QtDeclarative.

Property Documentation

property : string

The property to be updated.

target : Object

The object to be updated.

value : any

The value to be set on the target object and property. This can be a constant (which isn't very useful), or a bound expression.

when : bool

This property holds when the binding is active. This should be set to an expression that evaluates to true when you want the binding to be active.

 Binding {
     target: contactName; property: 'text'
     value: name; when: list.ListView.isCurrentItem