Data Binding

Supported for Eclipse 3.3 and above only

Data binding allows easy linking of UI elements and models so that users can edit or view the data in the model. Traditionally, this is what you need to do to link, say, a text widget to a String property of a model object:

  • Copy the current value of the model property to the text widget.

  • Register listeners with the widget and the model object to propagate changes made on one side to the other side.

The same basic principle applies to binding a list widget's contents to a collection property of a model object.

Using the data binding framework relieves you from writing and registering listeners yourself, and provides a common infrastructure for validation and conversion. It makes it easy to connect data sources to widgets such as text fields, combos, tables and trees, for viewing and editing. In real life scenarios, changes on one side are not always propagated to the other side right away - changes need to be validated, values converted, and different update policies followed. The data binding framework covers these more advanced aspects as well.

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Designer can create new Data Bindings in several different ways:

  • Clicking the Edit Data Bindings button on the main Designer toolbar to open the Edit Data Bindings dialog.

  • Right-clicking on a widget and selecting the Data Binding menu

  • Expanding the bindings property in the property pane

Designer will generate or update any necessary data binding code which may then be seen in the Source view.

Detailed data binding example code is available here.

Edit Data Binding Dialog

The Edit Data Bindings dialog can be opened by clicking the Edit Data Bindings button on the main Designer toolbar.

The Edit Data Bindings dialog supports the creation of two types of data bindings:

Data Binding Menu

The Data Bindings menu provides the ability to quickly create or edit data bindings for a widget. If the widget does not have any data bindings, the menu immediately cascades out to show the available properties of the widget that can be bound to a model property. If the widget has existing data bindings, those are shown at the top of the cascaded menu followed by a separator and a list of widget properties. Clicking on an unbound property will open the Create Data Binding wizard while clicking a bound property will open the Edit Data Binding dialog.

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Bindings Property

The bindings property in the property pane opens up to show a list of all bindable properties of the widget. Clicking the button next to an unbound property will open the Create Data Binding wizard while clicking the button next to a bound property will open the Edit Data Binding dialog.

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Icon Decorator

Any widget with a data binding assigned to will show up in the component tree with an icon decorator:   

Source

Designer will generate or update any necessary data binding code which may then be seen in the Source view. An initDataBindings() method is created, if it does not already exist and a call to that method is added to the end of the widget creation process.

Within the initDataBindings() method, any needed observables are created first followed by the creation of the Data Binding Context. Simple SWT data bindings are then created using the new context followed by any JFace content providers, list providers and inputs that are needed.

Warning: do not edit the initDataBinding() method by hand (without carefully matching the code generation pattern used by Designer) as it will be regenerated in its entirety any time Designer needs to add, remove or update a data binding.

Preferences

Various preferences are available to control the data binding code that is generated.