Fixing MVP with RxJava

How I cleaned up my implementation of MVP with RxJava

Transcript

1. Fixing MVP With RxJava
2. What’s the problem? Current implementations of MVP tend to become really messy Fragile & confusing testing nightmare https://github.com/googlesamples/android-architecture
3. MVP
4. MVP
5. MVP Activity manages part of the view We control the other part of the view
6. MVP Circular dependency between presenter and view View <-> presenter interaction becomes a spider web with no end in sight
7. MVP Code was never separated only smudged
8. Android RxMVP Reactive, Model, View and Presenter
9. RxMVP Treat the activity/fragment as a main method, not a view Create a standalone separate view that the system renders Use RxJava to implement observer pattern Treat system data events the same as app data events
10. Why integrate RxJava? Common abstraction for observing events and thread management Fixes circular dependency between Model, View and Presenter with the observer pattern Removes some OOP in favour of reactive functional programming Easy to modularise for reuse Makes mocking events for testing very easy
11. RxMVP
12. RxMVP - Activity/Fragment Bridge to android system Creates and manages Model, View and Presenter Acts as a data source for the model Provides context for view inflation Informs presenter of lifecycle events
13. Lifecycle Events View Dagger 2 injecting view + presenter Activity passed to view and model
14. RxMVP - View Separated into a single composite view/pojo containing a composite view Instantiated by us or DI so we have control over constructor arguments Activity displays view using the setContentView() method after injection/instantiation No dependency on the presenter, emit events via Rx observables
15. Custom constructor Observable clicks Data setter Java!
16. RxMVP - Model Proxy between data sources and the presenter Manages all data events from activity such as saved states, intent data, activity for result Simple logic, the odd map or a filter. Does not have complex data processing Can be split multiple classes, Data Model, Navigation, System
17. Restore State after config change Observable (RxState) Save State for config changes (RxState) Activity as dependency System call (Android) Network call (retrofit) Activity as data source
18. RxMVP - Presenter Uses Rx to glue views and models together. Completely “stateless”- contained by RxJava
19. Lifecycle Events View Events Model call Rx Subscriptions Subscriptions cancelled
20. Multi-pane Reuse views across activities Can use a container view composed of views Wireframe relays data from one model to the other.
21. Testing All components except views can be unit tested using mocks Events easily mocked using Observable.just(), Observable.never() etc Views tested using espresso and test data
22. Lifecycle event Verify Mock model and view Observable.never() = No click event Test data Observable Test Rx Schedulers
23. Show me the code Sample app on github https://github.com/TwistedEquations/android-rxmvp
24. Rx Libraries RxState - Maps saving state to Observable allowing saving at any point in an Rx chain https://github.com/TwistedEquations/android-rxstate
25. Rx Libraries RxIntent - Observable wrapping for startActivityForResult https://github.com/TwistedEquations/android-rxintents
26. Rx Libraries AndroidRxSchedulers - Injectable schedulers optimised for android https://github.com/TwistedEquations/android-rx-schedulers
27. Beware the golden hammer!
28. Questions? @twistedequat https://github.com/TwistedEquations patrick@twistedequations.com