GWT 2.1 MVP (Activities/Places) and Tabbed Displays

Question

On an existing project we’re using MVP (hand crafted) reasonably well. It’s understood and does mostly what we need. For a new project I'm looking at using the MVP framework built into GWT 2.1 (Activities and Places).

Our applications are mostly tabbed displays with each tab bound to a single view widget.

I’ve tried to use Activities and Places without success for this type of display. Part of the problem is that the example Hello World article ended up leaving me chasing my tail, too many new concepts for my brain to digest.

The Hello World sample IMO is not a sufficient introduction and doesn’t deal with many of the real world use cases. I was hoping someone could point me in the direction of any sample applications that use MVP for tabbed displays. Thomas Broyer has some excellent posts on his blog but these have still left me a little perplexed.

Previously I’ve used an AppController to handle tabs changes and single presenters for each tab. The new architecture in GWT 2.1 leaves me more confused that it should.

Answer 1

I'm using the gwt Activities/Places framework for a tabbed display, and it works great, BUT: I decided to abandon the TabLayoutPanel widget we had been using and create my own navbar (that looks like tabs) and a content pane. The effect is the same - it looks identical - but the implementation is much cleaner.

I think the problem is in trying to mix Activities/Places, which has its own idea of navigation, with a TabPanel, which has another idea of navigation. At first I tried to throw them together, overriding tab button behavior to trigger a PlaceController, which in turn switched the tabs around, but... it was messy. With the independent navbar / content pane, the PlaceController could do everything just like it wanted to. You just have to manually switch the views, instead of letting a TabPanel do it for you.

Answer 2

I also faced this problem but managed to make it work using one activity per Tab and each activity using a presenter (or more) to display the components of the tab.

Regarding the solution found by Riley Lark, I, instead, opted by using a Decorator pattern and, so, keep the original TabbedPanel. How ? Each activity gets injected (GIN) a presenter that contains a decorator for the TabbedPanel.

So, for example:

• Tab1Activity gets injected with Tab1Presenter, which, in turn, gets injected with Tab1Decorator which decorates the TabbedPanel with a Tab1ContentPanel (this panel contains all the widgets to be displayed on the Tab1 tab)

• Tab2Activity gets injected with Tab2Presenter, which, in turn, gets injected with Tab2Decorator which decorates the same TabbedPanel with a Tab2ContentPanel (this panel contains all the widgets to be displayed on the Tab2 tab)

Seems complex but, after creating the first decorator, it really paid off and I was able to keep the TabbedPanel and take advantage of the URL history management implicit in the framework.