CODEWITHSUNDEEP
javaeclipse-rcpe4
TheGrav
TheGrav

Reputation: 66

How can I switch perspective programmatically after starting an E4 application?

Scenario

I have a pure E4 application in which I want to select the initial perspective for the user depending on the user's roles. I therefore have a perspective to start with which contains one part only. In that part, I use the @PostConstruct-Method to check the user's roles and afterwards trigger the command for switching perspective:

Initial View

@Inject
private IEclipseContext eclipseContext;

@PostConstruct
public void initialize() {
  // checking credentials and retrieving roles come here which is pretty long
  // that's why switching perspective is a seperate method 
  // and EclipseContext is injected to instance instead of method
  this.switchPerspective(_usersInitialPerspectiveId)
}

private void switchPerspective(String pTargetPerspectiveId) {
  final ECommandService _commandService = this.eclipseContext.get(ECommandService.class);
  final EHandlerService _handlerService = this.eclipseContext.get(EHandlerService.class);

  final Map<String, Object> _commandParameter = new HashMap<>();
  _commandParameter.put(PluginIdConstants.ID_OF_PARAMETER_FOR_SWITCH_PERSPEKTIVE,
     pZielPerspektiveId);

  final ParameterizedCommand _switchPerspectiveCommand =
     _commandService.createCommand(COMMAND_ID_FOR_SWITCH_PERSPECTIVE,
        _commandParameter);
  _handlerService.executeHandler(_switchPerspectiveCommand);
}

For switching perspective from here, I use the exact same handler as from menu items configured in Application.e4xmi, which looks like this:

Perspective Switch Handler

@Execute
public void execute(final MWindow pWindow,
                    final EPartService pPartService,
                    final EModelService pModelService,
                    @Named(PluginIdConstants.ID_OF_PARAMETER_FOR_SWITCH_PERSPEKTIVE)
                    final String pPerspectiveId) {

  final List<MPerspective> _perspectives =
       pModelService.findElements(pWindow, pPerspectiveId, MPerspective.class, null);
  if (!(_perspectives.isEmpty())) {
     // Show perspective for looked up id
     pPartService.switchPerspective(_perspectives.get(0));
  }
}

The Problem

The problem is pretty simple: When using the above handler triggered by a menu item, it works as intended and switches perspective. But using the same handler by my initial view (triggering it programmatically) does not switch perspective. I debugged the code to check if the handler gets identical information in both cases and it does.

Maybe my application has not finished starting and that's why the handler has no effect, but if this is the problem, how can I check this?

Any ideas on what I maybe missed are welcome!

Upvotes: 1

Views: 1127

Answers (1)

TheGrav
TheGrav

Reputation: 66

Based on Christoph Keimel's hint I could create a working solution (thank you very much!). Here's the code that solves the problem:

@ProcessAdditions
private void switchPerspective(final MApplication pApplication,
                               final IApplicationContext pApplicationContext,
                               final EModelService pModelService) {

  final MWindow _window =
     (MWindow) pModelService.find(PluginIdConstants.WINDOW_ID_FOR_MAIN, pApplication);

  final String _appName = pApplicationContext.getBrandingName();
  initializeWindowTitle(_window, _appName);

  final MPerspectiveStack pPerspectiveStack =
     (MPerspectiveStack) pModelService.find(PluginIdConstants.PERSPECTIVE_STACK_ID_FOR_MAIN,
        pAnwendung);

  for (final MPerspective _perspective : pPerspectiveStack.getChildren()) {
     if (_perspektive.getElementId().equalsIgnoreCase(this.startingPerspectiveId)) {
        pPerspectiveStack.setSelectedElement(_perspective);
        break;
     }
  }
}

On how to register a LifeCycleHandler you can take a look at Lars Vogel's Tutorial.

My main problem finding this solution was how to access the perspective stack. As the UI is not up while the method annotated with ProcessAdditions is running, I have to access the application model via the MApplication type - which is the root element of my application model. Combining the EModelService I can access all UI elements I want and manipulate them accordingly. Injecting any UI element like the MPerspectiveStack or the MWindow leads to a skipped method as these result in null values due to not being initalized yet.

Upvotes: 2

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