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How to call data binding from a toolbar handler [message #867280]

Tue, 01 May 2012 04:02

Eclipse User

Hi all,

Good day! I would like to ask for help regarding the
accessing of data binding from the handler side.Declaration of the UI component, model and binding context are declared in viewpart. The scenario is: upon clicking the next button in the toolbar the next row will be selected in the table and the databinding should be activated so that the details form in the right side will be called.I already make a working code only for table traversal in the viewpart without error. Now when I called it in the handler it kinda work but throws error.Thanks in advance! I hope I can receive a positive response. I am new to data binding and handler usage.

Regards,
Lanz

Re: How to call data binding from a toolbar handler [message #868442 is a reply to message #867280]

Tue, 01 May 2012 20:58

Eclipse User

Hi all,

I addressed the error by creating instance of another databinding context in the handler as seen below:
//-->>
public class PreviousHandler extends AbstractHandler {

@Override
public Object execute(ExecutionEvent event) throws ExecutionException {
IWorkbenchPart part = HandlerUtil.getActivePart(event);
int currentSelectedRow= -1;
int previousRow= -1;

...
IObservableValue masterSelection = germplasmDataEntryViewPart.getMasterSelection();

DataBindingContext ctx = new DataBindingContext();
IObservableValue widgetValue = WidgetProperties.text(SWT.Modify).observe(germplasmDataEntryViewPart.getTextTrait1());
IObservableValue modelValue = BeanProperties.value(Germplasm.class, "trait1").observeDetail(
masterSelection);
ctx.bindValue(widgetValue, modelValue);

...
//<<--

In here I don't know why I have to create a binding on at least one UI component(textfield) just to trigger the binding in the viewpart.
Without this, databinding is not activated as I traverse the rows of the table via next,previous button in the toolbar.
Nevertheless, this works. Any ideas?

-Lanz

Re: How to call data binding from a toolbar handler [message #868456 is a reply to message #868442]

Tue, 01 May 2012 22:04

Eclipse User

I'm sorry this is still wrong because creating an instance of a new databinding context in the handler conflicts with another databinding context declared
in the viewpart. So again I tried the code below for the handler. This works but throws an error:

//-->>
DataBindingContext ctx = germplasmDataEntryViewPart.getBindingContext();//new DataBindingContext();
//<<--

!ENTRY org.eclipse.ui 4 0 2012-05-02 09:52:44.968
!MESSAGE Unhandled event loop exception
!STACK 0
java.lang.NullPointerException
at org.irri.inger.ingeris.prototype.handler.NextHandler.execute(NextHandler.java:91)
at org.eclipse.ui.internal.handlers.HandlerProxy.execute(HandlerProxy.java:293)
at org.eclipse.core.commands.Command.executeWithChecks(Command.java:476)
at org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(ParameterizedCommand.java:508)
at org.eclipse.ui.internal.handlers.HandlerService.executeCommand(HandlerService.java:169)
at org.eclipse.ui.internal.handlers.SlaveHandlerService.executeCommand(SlaveHandlerService.java:241)
at org.eclipse.ui.menus.CommandContributionItem.handleWidgetSelection(CommandContributionItem.java:829)
at org.eclipse.ui.menus.CommandContributionItem.access$19(CommandContributionItem.java:815)
at org.eclipse.ui.menus.CommandContributionItem$5.handleEvent(CommandContributionItem.java:805)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4165)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3754)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.irri.inger.ingeris.prototype.Application.start(Application.java:86)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:344)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
at org.eclipse.equinox.launcher.Main.main(Main.java:1386)

Your ideas are welcome!
Thanks,
Lanz

Re: How to call data binding from a toolbar handler [message #869031 is a reply to message #868456]

Wed, 02 May 2012 17:49

Eclipse User

Hi Lanz,
making the databinding in the handler is somewhat strange: the detail view should be aware of selection change (whoever is firing it) and provide for its own databinding.

I suggest the following pattern.

1) in the view that contains the table in which the selection changes do this when you create the tableviewer

getViewSite().setSelectionProvider(viewer);

(this will fire the selection change to whoever will register for this event)

2) in the detail view, when creating the widgets do this:

PlatformUI.getWorkbench().getActiveWorkbenchWindow()
		.getSelectionService()
		.addSelectionListener(new ISelectionListener() {
			@Override
			public void selectionChanged(IWorkbenchPart part,
					ISelection selection) {
				//Selection is changed => call the databinding
			}
		});

3) since the databindings on a new selection should be made after having removed the databindings on the old selection, it is advisable using a WritableValue attribute, which takes care of this automatically. Just do this:
define, in the detail view, a WritableValue

private WritableValue value = new WritableValue();

the use it to bind to the widgets (an example of this can be found among our tutorials (search "RCP Vision WindowBuilder: advanced databinding with CDO" on Google), just see the part after the definition of the WritableValue)

Hope this help
Let me know

Vincenzo Caselli
RCP Vision

Re: How to call data binding from a toolbar handler [message #869159 is a reply to message #869031]

Wed, 02 May 2012 22:35

Eclipse User

Hi Vincenzo,

I'm sorry I am having a hard time implementing your suggestion. The table and the other UI components for detail information are
all in a single viewpart. The handler need to activate the data binding when the user clicks
on the toolbar item next and previous button. What I did was I created a dummy text field in the viewpart
with a dummy attribute in the model class(Germplasm); and make this this dummy text field invisible. Now it's working.
//-->> in the viewpart
dummyFieldText = new Text(grpSeedTraits, SWT.BORDER);
dummyFieldText.setBounds(304, 75, 76, 19);
dummyFieldText.setVisible(false);
//<<--

//-->> in the handler
DataBindingContext ctx = germplasmDataEntryViewPart.getBindingContext();
IObservableValue widgetValue = WidgetProperties.text(SWT.Modify).observe(germplasmDataEntryViewPart.getDummyFieldText());
IObservableValue modelValue = BeanProperties.value(Germplasm.class, "dummyField").observeDetail(
masterSelection);
ctx.bindValue(widgetValue, modelValue);

//<<--

You're ideas are welcome.

Regards,
Lanz

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