How to pass additional data to GWT sub-editors? - gwt

Question

i have this issue:
I have a PresenterWidget which contains sub-editors.
There are "container" elements which should be editable by this widget. These containers can be assigned to groups. To do so, i would like to fetch a list of all available groups from the server. So the widget is set up like this (i use GWTP):
public class ContainerEditorDialogPresenterWidget extends PresenterWidget<ContainerEditorDialogPresenterWidget.MyView> implements
ContainerEditorDialogUiHandlers {
private final PlaceManager placeManager;
private List<GroupDTO> groupList = new ArrayList<GroupDTO>();
private final DispatchAsync dispatcher;
#Inject
ContainerEditorDialogPresenterWidget(EventBus eventBus,
MyView view, PlaceManager placeManager, DispatchAsync dispatcher) {
super(eventBus, view);
getView().setUiHandlers(this);
this.dispatcher = dispatcher;
fetchGroups();
}
...
public void fetchGroups(){
FetchGroupsAction action = new FetchGroupsAction();
dispatcher.execute(action, new AsyncCallbackImpl<FetchGroupsResult>() {
#Override
public void onSuccess(FetchGroupsResult result) {
groupList = result.getGroupDtos();
eventBus.fireEvent(new GroupListUpdatedEvent(groupList));
}
});
}
So i call fetchGroups in the constructor to get it as early as possible. Since it is an AynchCallback, i get the result back "at some time". I then try to pass the values to the sub-editor with a GroupListUpdatedEvent. In there i have a Editor declared like this:
public class GroupListEditor extends Composite implements
IsEditor<ListEditor<String, GroupItemEditor>> {
private static StringListEditorUiBinder uiBinder = GWT
.create(StringListEditorUiBinder.class);
interface StringListEditorUiBinder extends
UiBinder<Widget, GroupListEditor> {
}
//Gives us access to the event bus.
#Inject private EventBus eventBus;
...
public GroupListEditor() {
initWidget(uiBinder.createAndBindUi(this));
eventBus.addHandler(GroupListUpdatedEvent.TYPE, new GroupListUpdatedEvent.GroupListUpdatedHandler() {
#Override
public void onGroupListUpdatedEvent(GroupListUpdatedEvent event) {
Log.debug("onContainerUpdatedEvent caught");
allGroups = event.getGroupList();
if(allGroups != null) {
for (GroupDTO g : allGroups) {
lbAllGroups.addItem(g.getName(), g.getId().toString());
}
lbAllGroups.setVisibleItemCount(5);
Log.debug("Item list = " + lbAllGroups.getItemCount());
} else {
Log.debug("GROUP LIST is Null!");
}
}
});
}
When i try to register the handler, i get an exception. So i expect the eventBus is not injected properly. What do i miss, how can i use events and the event bus if i am not in a Presenter?
And: Is this the right way at all to populate Editors with "utility" data? I guess Editor should be related directly to the data they care for. But how do i handle this kind of supplemental data?
Thanks :)

Answer 1

Do you use #UiField in your ContainerEditorDialogPresenterWidgetView for your GroupListEditor ?
If so then Dependency Injection won't work because you basically manually create the GroupListEditor which leads to EventBus being NULL.
I would also use Constructor Injection instead of field injection.
GroupListEditor:
#Inject
public GroupListEditor(EventBus eventBus) {
this.eventBus = eventBus;
}
ContainerEditorDialogPresenterWidgetView:
public class ContainerEditorDialogPresenterWidgetView {
#UiField(provided=true)
GroupListEditor groupListEditor;
#Inject
public ContainerEditorDialogPresenterWidgetView(GroupListEditor groupListEditor);
this.groupListEditor = groupListEditor;
initWidget();
}
}
Alternatively you could get an instance of your GroupListEditor via the Ginjector directly.