GDG DevFest in Taipei 2019: Enjoy DI life with Koin

When mentioning about DI framework on Android, in addition to Dagger2, there is actually another alternative, Koin. Koin is a lightweight dependency injection framework written in pure Kotlin. As a DSL, Koin provides a pragmatic API that significantly simplifies the injection process.

This session will talk about how easy to set up the dependencies in Koin and how easy to inject instances. Besides, We will demonstrate how to integrate Koin with Model-View-Presenter (MVP) and Model-View-ViewModel (MVVM). Lastly, we will talk about testing with Koin.

Transcript

2. Aaron Chu Android Developer @ LINE
3. Enjoy DI life with Koin Aaron Chu
4. Agenda • Dagger2 • Koin Basics • Model-View-Presenter (MVP) with Koin • Model-View-ViewModel (MVVM) with Koin • Inject Anywhere • Koin Test
5. Agenda • Dagger2 • Koin Basics • Model-View-Presenter (MVP) with Koin • Model-View-ViewModel (MVVM) with Koin • Inject Anywhere • Koin Test
6. Dagger2 @Component @Module @Provides @Singleton @Scope @Qualifier @Named @Inject @SubComponent @ContributesAndroidInjector AndroidSupportInjectionModule AndroidInjector @Binds @Component.Builder @Component.Factory @IntoMap @BindsInstance @MapKey @Reusable MembersInjector HasAndroidInjector DaggerAppCompatActivity @BindsOptionalOf DaggerApplication
7. Agenda • Dagger2 • Koin Basics • Model-View-Presenter (MVP) with Koin • Model-View-ViewModel (MVVM) with Koin • Inject Anywhere • Koin Test
8. Koin
9. What is Koin? A pragmatic lightweight dependency injection framework for Kotlin developers. Written in pure Kotlin using functional resolution only: no proxy, no code generation, no reflection! Koin is a DSL, a lightweight container and a pragmatic API.
10. Koin Setup (1/2) Define module
11. Koin Setup (1/2) Define module
12. Koin Setup (1/2) Define module
13. Koin Setup (2/2) Start Koin
14. Koin Setup (2/2) Start Koin
15. Koin Injection
16. Koin Injection
17. Koin Injection
18. Binding an Interface
19. Naming definitions
20. • Activity • Fragment • Service • ContentProvider • Broadcast Receivers • ... inject() and get() are extension functions of ComponentCallbacks interface Where are inject() and get() from?
21. Agenda • Dagger2 • Koin Basics • Model-View-Presenter (MVP) with Koin • Model-View-ViewModel (MVVM) with Koin • Inject Anywhere • Koin Test
22. Model-View-Presenter (MVP) with Koin
23. Model-View-Presenter (MVP) with Koin
24. Model-View-Presenter (MVP) with Koin
25. Model-View-Presenter (MVP) with Koin
26. Model-View-Presenter (MVP) with Koin
27. Model-View-Presenter (MVP) with Koin
28. Model-View-Presenter (MVP) with Koin
29. Model-View-Presenter (MVP) with Koin
30. Model-View-Presenter (MVP) with Koin
31. Model-View-Presenter (MVP) with Koin
32. Model-View-Presenter (MVP) with Koin
33. Model-View-Presenter (MVP) with Koin
34. • FragmentActivity • AppCompatActivity • Fragment • DialogFragment • ... Where is currentScope from? currentScope is an extension property of LifecycleOwner
35. Agenda • Dagger2 • Koin Basics • Model-View-Presenter (MVP) with Koin • Model-View-ViewModel (MVVM) with Koin • Inject Anywhere • Koin Test
36. Model-View-ViewModel (MVVM) with Koin
37. Model-View-ViewModel (MVVM) with Koin
38. Model-View-ViewModel (MVVM) with Koin
39. Model-View-ViewModel (MVVM) with Koin
40. Model-View-ViewModel (MVVM) with Koin
41. Model-View-ViewModel (MVVM) with Koin
42. Model-View-ViewModel (MVVM) with Koin
43. Model-View-ViewModel (MVVM) with Koin
44. Where are viewModel() and sharedViewModel() from? viewModel() and getViewModel() are extension functions of LifecycleOwner sharedViewModel() and getSharedViewModel() are extension functions of Fragment
45. Agenda • Dagger2 • Koin Basics • Model-View-Presenter (MVP) with Koin • Model-View-ViewModel (MVVM) with Koin • Inject Anywhere • Koin Test
46. What if I want to inject anywhere?
47. KoinComponent KoinComponent interface provides getKoin() for accessing the global Koin instance
48. KoinComponent Extensions
49. KoinComponent Extensions
50. KoinComponent Any class implementing the KoinComponent can utilize the handy extension functions of inject() and get()
51. KoinComponent Any class implementing the KoinComponent can utilize the handy extension functions of inject() and get()
52. Inject instance declared in scoped() anywhere
53. Inject instance declared in scoped() anywhere
54. Inject instance declared in scoped() anywhere
55. Inject instance declared in scoped() anywhere
56. Inject instance declared in scoped() anywhere
57. Inject view model declared in viewModel() anywhere? No, because ViewModel is tied to FragmentActivity and Fragment. The way of getting a ViewModel, • ViewModelProviders.of(FragmentActivity).get(...) • ViewModelProviders.of(Fragment).get(...)
58. Inject view model declared in viewModel() anywhere?
59. Agenda • Dagger2 • Koin Basics • Model-View-Presenter (MVP) with Koin • Model-View-ViewModel (MVVM) with Koin • Inject Anywhere • Koin Test
60. Koin Test
61. Check Modules
62. Check Modules
63. Check Modules
64. Check Modules with Paramenters
65. Check Modules with Paramenters
66. Declare Mocks on the Fly
67. Declare Mocks on the Fly ↑ want to mock this
68. Declare Mocks on the Fly
69. Declare Mocks on the Fly
70. Declare Mocks on the Fly
71. Declare Mocks on the Fly
72. Declare Mocks on the Fly for Scope
73. Declare Mocks on the Fly for Scope ← want to mock this
74. Declare Mocks on the Fly for Scope
75. Declare Mocks on the Fly for Scope
76. Scope.declareMock() will be released in Koin 2.0.2 https://github.com/InsertKoinIO/koin/pull/546 Declare Mocks on the Fly for Scope
77. Declare Mocks on the Fly for Scope
78. Declare Mocks on the Fly for Scope
79. Koin setup with startKoin() and declared definitions • single(), factory() • scope(), scoped() • viewModel() Summary
80. • single(), factory() ◦ inject(), get() from CallbackComponents or KoinComponent • scope(), scoped() ◦ currentScope from LifecycleOwner ◦ koin.createScope(...) from KoinComponent • viewModel() ◦ viewModel() from FragmentActivity, sharedViewModel() from Fragment Koin injection from different definitions Summary
81. Summary Koin integration with architectural design patterns • Model-View-Presenter (MVP) • Model-View-ViewModel (MVVM)
82. Summary Koin test • startKoin() with predefined modules and AutoCloseKoinTest • KoinApplication.checkModules() • KoinTest.declareMock() for non-scope definitions • Scope.declareMock() for scope definitions
83. THANK YOU