Bug 140644 [DataBinding] Binding to ValidationError of DataBindingContext is broken
Hello, I wanted to bind the ValidationError Observable to a Widget, and it doesn't seem to work. I tested with Jface Databinding sample and in TestMasterDetails.java example, instead of binding the simple date error to a label, I bound the ValidationError of DBC to the Label (with a simple converter). dbc.bind(validationError, dbc.getValidationError(), new BindSpec().setUpdateModel(false).setModelToTargetConverter(new IConverter() { public Object convert(Object fromObject) { // TODO Auto-generated method stub if (fromObject == null) return null; return ((ValidationError) fromObject).message; } public Object getFromType() { // TODO Auto-generated method stub return Object.class; } public Object getToType() { // TODO Auto-generated method stub return String.class; } })); After investigating, I saw the ValidationError is a computed value (very interesting concept and useful) on the ValidationErrorList. 1. The ComputedValue mechanism seems to use the StateListener to the Object, but I don't see any management of staleness in ValidationErrorList (or ObservableList). 2. When one of the field gets an error, I debug and saw the ChangedListener on my binding was null (whereas the ValidationErrorList registers listeners on them). At the beginning, it's registered, the removed and not added again when needed. I have not enough time to go deeper in the mechanism, could you help me to understand what I'm doing wrong with this simple binding (With previous releases I was already binding with that mechanism and it worked). Is there an other way to do this? (My workaround is a listener on DBC, but I would prefer to use ValidationError Computed value). Thanks in advance
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/DataBindingContext.java
* event occurs in the data flow pipeline that is managed by any binding
	 * created by this data binding context.
	 * 
	 * @param listener
	 *            The listener to add.
	 */
	public void addBindingEventListener(IBindingListener listener) {
		bindingEventListeners.add(listener);
	}
	/**
	 * Adds a factory that can create converters and validators. The list of
	 * bind support factories is used for creating converters and validators
	 * when binding without specifying a converter or validator.
	 * 
	 * @param factory
	 *            the factory to add.
	 */
	public void addBindSupportFactory(BindSupportFactory factory) {
		bindSupportFactories.add(factory);
	}
	/**
	 * Binds two observable values using converter and validator as specified in
	 * bindSpec. If bindSpec is null, a default converter and validator is used.
	 * 
	 * @param targetObservableValue
	 * @param modelObservableValue
	 * @param bindSpec
	 *            the bind spec, or null. Any bindSpec object must not be reused
	 *            or changed after it is passed to #bind.
	 * @return The Binding that manages this data flow