Let's talk about MVVM

Let's talk about MVVM

Transcript

1. MVVM Architecture Pattern BM JayJay
2. LET'S TALK ABOUT ARCHITECTURE
3. Let's try to understand in a very simple manner: • Why do we authentically need them? ◦ Best practices. ◦ Speed up development. ◦ Programming independent. ◦ Flexible, reusable and maintainable. • How can we achieve it? ◦ e.g: MVC, MVP, MVVM, VIPER, VIP, etc.
4. LET'S TALK ABOUT MVVM
5. INTRODUCING MVVM VIEW VIEWMODEL MODEL • View ◦ Handles its own UI events. ◦ That informs the ViewModel about the user’s actions. ◦ It observes the ViewModel. • ViewModel ◦ Binds data to the View. ◦ Does not directly reference the View. ◦ It servers as a link between the Model and View. • Model ◦ Often split into layers itself: Business logic, Data access, Data retrieval. The separate code layers of MVVM are: 1 2 3 4
6. LAYER DIAGRAM
7. VIEW VIEWMODEL REPOSITORY DATA SOURCE
8. VIEW VIEWMODEL REPOSITORY DATA SOURCE • Activities & Fragments • Observers the ViewModel • Keeps the UI up-to-date • Forwards user Actions back to the ViewModel
9. VIEW VIEWMODEL REPOSITORY DATA SOURCE • Prepares & keeps the data for UI • Includes LiveData, Observable etc. • Survives configuration changes • The gateway for the UI Controller
10. VIEW VIEWMODEL REPOSITORY DATA SOURCE • The complete data model for App. • Providers simple data modification & retrieval APIs. • Coordinates fetching, syncing, persisting etc from different data sources.
11. VIEW VIEWMODEL REPOSITORY DATA SOURCE API to the data sources • e.g. Retrofit for a REST API • Room for local persistence • Content Providers
12. VIEW VIEWMODEL REPOSITORY DATA SOURCE CharactersListFragment CharactersListViewModel MarvelRepository MarvelService
13. CharactersListFragment
14. CharactersListViewModel
15. MarvelRepository
16. MarvelService
17. Benefits • Breaks up code by responsibility. • Business logic is decoupled from UI. • Code reusability. • Simplifies testing. “For simple UI, M-V-VM can be overkill. In bigger cases, it can be hard to design the ViewModel up front in order to get the right amount of generality” - John Gossman Disadvantages?
18. How to use MVVM pattern in Android BM Boe
19. That's all Thank you!