Question: Is it possible to listen in UI to specific ACTION only?

[sandsaber]

Hi, Thanks for so cool implementation of redux, just quick question, is it possible to listen in UI to specific ACTION only? I see:

mCancelable = Cursors.forEach(store, state -> {
            adapter.setNotes(state.getFilteredNotes());
            spinner.setSelection(state.filter().ordinal());
        });

In the example, so each time any action popup, it will call update, but what, if I want to do specific UI changes on specific ACTION? :)

[Yarikx]

Hi @sandsaber

There are a couple of ways to do that. Can you provide some example why do you need one?

You can create Middleware that will listen to specific actions and propagate them however you want.

[sandsaber]

Basically, idea is simple: update UI when it really needed. I can modify data but UI should be not affected. Middleware sounds good, yes, forgot about it >_< Any examples how it can be used with UI? If I need pass to UI that it need redraw store state.

Maybe this example will be better: If we have store with a lot of data, which take some time to filter fo example, we can filter it async and then let UI know that data ready to show.

[Yarikx]

But if you just want to only update the UI when some subset of your data changes you can use Cursors.map(fn). provide the function that will map your state to some substate (let's say a few fields), and map will propagate it only when that substate changes. That is equal to stateObserable.map(fn).distinctUntilChanged() in RxJava

[sandsaber]

Good point, thank you! One more question :) As I understood currently whole flow of redux running synchronously? You mention that you plan create Async example, can you share? :) Wanna see your version of it :)

[Yarikx]

Oh, yeah. It's supported, I just need to provide an example. You can use RxJava for it. Check out how JS community is using https://github.com/redux-observable/redux-observable. Reudctor-observable id direct port of it. With it you can define epics like that:

Epic<String> pingPongEpic = (actions, store) ->            
        actions.filter(Epics.ofType("PING"))           
                .delay(1, TimeUnit.SECONDS)            
                .map(action -> Action.create("PONG")); 

Basically you can observe actions (and state) as observable and dispatch actions back to the store.

[sandsaber]

Thanks for help!