Dependency Injection from zero to hero with koin

Transcript

1. Dependency Injection from 0 -> ‍♂ using koin Teja Chirala Android Developer @Mindvalley GDG Kuala Lumpur
3. Kuala Lumpur We are hiring!!! http://careers.mindvalley.com/positions
4. Kuala Lumpur • 300+ employees • 50+ Nationalities • 40+ Languages spoken. Top 10 world’s coolest offices Inc. magazine (2012, 2019) • Malaysia’s healthiest employees , 2019 • Malaysia’s healthiest workplace , 2019 • Malaysia’s healthiest employer , 2019
5. Kuala Lumpur We are hiring!!! http://careers.mindvalley.com/positions
6. What is Dependency Injection? Kuala Lumpur
7. What is a dependency? Kuala Lumpur Printer PaperTray • Class needs another class to perform a task. • All apps have dependencies. Dependency
8. What is a dependency Injection? Kuala Lumpur Printer PaperTray • Dependencies are provided / injected to the class instead of the class creating them itself.
9. Without DI class Printer { private val paperTray: PaperTray = PaperTray() } Kuala Lumpur Printer PaperTray
10. With DI Kuala Lumpur Printer PaperTray ??? PaperTray
11. Kuala Lumpur How to Inject?
12. With DI - Constructor Injection class Printer(val paperTray: PaperTray) { } fun main(args: Array) { val paperTray = PaperTray() val printer = Printer(paperTray) } Kuala Lumpur Printer PaperTray
13. With DI - Setter Injection class Printer() { lateinit var paperTray: PaperTray } fun main(args: Array) { val printer = Printer() printer.paperTray = PaperTray() } Kuala Lumpur Printer PaperTray
14. Importance of DI Kuala Lumpur
15. Importance of DI Kuala Lumpur • Helps in achieving Separation of concerns of construction and use of objects
16. Reuse Printer fun main(args: Array) { val a4Printer = Printer(A4SizePaperTray()) val a1Printer = Printer(A1SizePaperTray()) } Kuala Lumpur
17. Importance of DI Kuala Lumpur • Helps in achieving Separation of concerns of construction and use of objects ◦ Readability ◦ Reusability • Decreases coupling between a object and its dependency
18. Importance of DI Kuala Lumpur • Helps in achieving Separation of concerns of construction and use of objects ◦ Readability ◦ Reusability • Decreases coupling between a object and its dependency • Ease of refactoring
19. class Printer() { //very, very long source code } Kuala Lumpur
20. class Printer( private val paperTray: PaperTray ) { //very long source code } Kuala Lumpur
21. class Printer( private val paperTray: PaperTray, private val scanner: Scanner, private val paperRoller: PaperRoller, private val ledInteractor: LEDInteractor ) { //small source code } Kuala Lumpur
22. Kuala Lumpur Printer
23. Kuala Lumpur PaperTray Printer LEDInteractor Scanner PaperRoller
24. Importance of DI Kuala Lumpur • Helps in achieving Separation of concerns of construction and use of objects ◦ Readability ◦ Reusability • Decreases coupling between a object and its dependency • Ease of refactoring ◦ Smaller foused classes • Easy tests
25. class PrinterTest { @Test fun `printer happy path`() { val printer = Printer(fakePaperBundle()) ... } } Kuala Lumpur
26. class PrinterTest { @Test fun `printer happy path`() { val printer = Printer(fakePaperBundle()) ... } @Test fun `printer empty paper`() { val printer = Printer(fakeEmptyPaperBundle()) ... } } Kuala Lumpur
27. Let’s get into details...‍♂ Kuala Lumpur
28. Kuala Lumpur Printer Roller +rollPaper() PaperBundle +canRollPaper() +setPaperRolled() +getPaper() PrinterRoller PaperTray
29. interface PaperBundle { fun getPaper() fun setPaperRolled() fun canRollPaper():Boolean } Kuala Lumpur class PaperTray: PaperBundle { private var paperCount = 10 private var canRollPaper = false override fun getPaper() { if (paperCount > 0) { println("Getting paper =>=>=>") paperCount-- canRollPaper = true } } override fun setPaperRolled() { canRollPaper = false } override fun canRollPaper() : Boolean { return canRollPaper } }
30. interface Roller { fun rollPaper() } Kuala Lumpur class PrinterRoller(private val paperBundle: PaperBundle): Roller{ override fun rollPaper() { if (paperBundle.canRollPaper()) { println("oooooo rolling oooooo") } } }
31. class Printer(private val paperBundle: PaperBundle, private val roller: Roller) { fun print() { paperBundle.getPaper() println("Printing.....") roller.rollPaper() } } Kuala Lumpur
32. val paperTray = PaperTray() val printerRoller = PrinterRoller(paperTray) val printer = Printer(paperTray, printerRoller) printer.print() Kuala Lumpur Manual DI - Problem?
33. Koin
34. Why Koin? Kuala Lumpur • Simple to read and understand • Meaningful • Not driven by theory alone • No over engineering
35. dependencies { def koinVersion = "2.0.1" implementation "org.koin:koin-android:$koinVersion" } Kuala Lumpur
36. //declare dependencies here module { } Kuala Lumpur
37. //declare dependencies here module { //definition Single | factory {} } Kuala Lumpur
38. //declare dependencies here module { //definition Single | factory { instance creation expression } } Kuala Lumpur
39. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { } Kuala Lumpur
40. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { } Kuala Lumpur
41. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single { PaperTray() } } Kuala Lumpur
42. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single<PaperBundle> { PaperTray() } } Kuala Lumpur
43. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single<PaperBundle> { PaperTray() } } Kuala Lumpur
44. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single<PaperBundle> { PaperTray() } single<Roller> { PrinterRoller() } } Kuala Lumpur
45. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single<PaperBundle> { PaperTray() } single<Roller> { PrinterRoller(???) } } Kuala Lumpur
46. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single<PaperBundle> { PaperTray() } single<Roller> { PrinterRoller(get<PaperBundle>()) } } Kuala Lumpur
47. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single<PaperBundle> { PaperTray() } single<Roller> { PrinterRoller(get()) } } Kuala Lumpur
48. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single<PaperBundle> { PaperTray() } single<Roller> { PrinterRoller(get()) } single { Printer(???, ???) } } Kuala Lumpur
49. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single<PaperBundle> { PaperTray() } single<Roller> { PrinterRoller(get()) } single { Printer(get(), get()) } } Kuala Lumpur
50. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single<PaperBundle> { PaperTray() } single<Roller> { PrinterRoller(get()) } single { Printer(get(), get()) } } Kuala Lumpur
51. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single { Printer(get(), get()) } } val printerComponentsModule = module { single<PaperBundle> { PaperTray() } single<Roller> { PrinterRoller(get()) } } Kuala Lumpur
52. startKoin to start Koin container Kuala Lumpur
53. Start Koin class MainApplication : Application() { override fun onCreate() { super.onCreate() startKoin { } } } Kuala Lumpur
54. Start Koin class MainApplication : Application() { override fun onCreate() { super.onCreate() startKoin { // Koin Android logger androidLogger() } } } Kuala Lumpur
55. Start Koin class MainApplication : Application() { override fun onCreate() { super.onCreate() startKoin { // Koin Android logger androidLogger() //inject Android context androidContext(this@MainApplication) } } } Kuala Lumpur
56. Start Koin class MainApplication : Application() { override fun onCreate() { super.onCreate() startKoin { // Koin Android logger androidLogger() //inject Android context androidContext(this@MainApplication) // use modules modules(printerModule) } } } Kuala Lumpur
57. Start Koin class MainApplication : Application() { override fun onCreate() { super.onCreate() startKoin { // Koin Android logger androidLogger() //inject Android context androidContext(this@MainApplication) // use modules modules(listOf(printerModule, printerComponentsModule)) } } } Kuala Lumpur
58. //Getting the dependencies class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) // ... } } Kuala Lumpur
59. //Getting the dependencies class MainActivity : AppCompatActivity() { // Eagerly injected Printer instance val printer : Printer = get() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) // ... } } Kuala Lumpur
60. //Getting the dependencies class MainActivity : AppCompatActivity() { // Lazy injected Printer instance val printer : Printer by inject() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) // ... } } Kuala Lumpur
61. //Getting the dependencies class MainActivity : AppCompatActivity() { // Lazy injected Printer instance val printer : Printer by inject() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) printer.print() } } Kuala Lumpur
62. Kuala Lumpur Getting paper =>=>=> Printing..... oooooo rolling oooooo
63. Koin component A class that can use the koin component Kuala Lumpur
64. Koin component is an interface marker Identify class linked to koin API ✅ Open access to koin extensions inject(),get() Kuala Lumpur
65. class PrinterApp { private val printer: Printer fun startPrinting() { printer.print() } } Kuala Lumpur
66. class PrinterApp: KoinComponent { private val printer: Printer by inject() fun startPrinting() { printer.print() } } Kuala Lumpur
67. Kuala Lumpur Printer Roller +rollPaper() PaperBundle +canRollPaper() +setPaperRolled() +getPaper() PrinterRoller PaperTray LAZY
68. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single<PaperBundle> { PaperTray() } single<Roller> { PrinterRoller(get()) } single { Printer(get(), get()) } } Kuala Lumpur
69. class PaperTray: PaperBundle class PrinterRoller(private val paperBundle: PaperBundle): Roller class Printer(private val paperBundle: PaperBundle, private val roller: Roller) val printerModule = module { single<PaperBundle> { PaperTray() } single<Roller> { PrinterRoller(get()) } single { Printer(lazy {get<PaperBundle>()}, get()) } } Kuala Lumpur
70. class Printer(private val paperBundle: PaperBundle, private val roller: Roller) { fun print() { paperBundle.getPaper() println("Printing.....") roller.rollPaper() } } Kuala Lumpur
71. class Printer(_paperBundle: Lazy<PaperBundle>, private val roller: Roller) { private val paperBundle by _paperBundle fun print() { paperBundle.getPaper() println("Printing.....") roller.rollPaper() } } * Lazy is Kotlin type Kuala Lumpur
72. class Printer(_paperBundle: Lazy<PaperBundle>, private val roller: Roller) { private val paperBundle by _paperBundle fun print() { paperBundle.getPaper() println("Printing.....") roller.rollPaper() } } Kuala Lumpur
73. Let’s get back with Dagger...
74. @Module abstract class PaperModule { @Binds abstract fun providesPaperTray(paperTray: PaperTray) : PaperBundle } Kuala Lumpur
75. @Module(includes = [PaperModule::class]) class RollerModule { @Singleton @Provides fun providesRoller(paperBundle: PaperBundle) : Roller { return PrinterRoller(paperBundle) } } Kuala Lumpur
76. class Printer @Inject constructor(_paperBundle: Lazy<PaperBundle>, private val roller: Roller) { private val paperBundle by lazy { _paperBundle.get() } fun print() { paperBundle.getPaper() println("Printing.....") roller.rollPaper() } } * Lazy is dagger type Kuala Lumpur
77. class Printer @Inject constructor(_paperBundle: Lazy<PaperBundle>, private val roller: Roller) { private val paperBundle by lazy { _paperBundle.get() } fun print() { paperBundle.getPaper() println("Printing.....") roller.rollPaper() } } Kuala Lumpur
78. @Module(includes = [RollerModule::class]) open class PrinterModule { @Singleton @Provides open fun providePrinter(paperBundle: PaperBundle, roller: Roller) : Printer { return Printer( Lazy {paperBundle} , roller) } } Kuala Lumpur
79. class ApplicationClass: Application() { override fun onCreate() { super.onCreate() val printerComponent = DaggerPrinterComponent.builder() .printerModule(PrinterModule()) .build() printerComponent.printer().print() } } Kuala Lumpur
80. Kuala Lumpur Getting paper =>=>=> Printing..... oooooo rolling oooooo
81. Let’s migrate Kuala Lumpur . . Dagger 2
82. Kuala Lumpur Printer Roller +rollPaper() PaperBundle +canRollPaper() +setPaperRolled() +getPaper() PrinterRoller PaperTray
83. Kuala Lumpur Printer Roller +rollPaper() PaperBundle +canRollPaper() +setPaperRolled() +getPaper() PrinterRoller PaperTray
84. Kuala Lumpur Printer Roller +rollPaper() PaperBundle +canRollPaper() +setPaperRolled() +getPaper() PrinterRoller PaperTray
85. val printerModule = module { single<PaperBundle> { PaperTray() } } Kuala Lumpur
86. class PrinterRoller @Inject constructor(private val paperBundle: PaperBundle): Roller { override fun rollPaper() { if (paperBundle.isPaperAvailable()) { println("oooooo rolling oooooo") } } } Kuala Lumpur
87. class PrinterRoller (private val paperBundle: PaperBundle): Roller { override fun rollPaper() { if (paperBundle.isPaperAvailable()) { println("oooooo rolling oooooo") } } } Kuala Lumpur
88. class PrinterRoller : Roller { private val paperBundle: PaperBundle override fun rollPaper() { if (paperBundle.isPaperAvailable()) { println("oooooo rolling oooooo") } } } Kuala Lumpur
89. class PrinterRoller : Roller, KoinComponent { private val paperBundle: PaperBundle by inject() override fun rollPaper() { if (paperBundle.isPaperAvailable()) { println("oooooo rolling oooooo") } } } Kuala Lumpur
90. class Printer @Inject constructor(_paperBundle: Lazy<PaperBundle>, private val roller: Roller) { private val paperBundle by lazy { _paperBundle.get() } fun print() { paperBundle.getPaper() println("Printing.....") roller.rollPaper() } } Kuala Lumpur
91. class Printer @Inject constructor(_paperBundle: Lazy<PaperBundle>, private val roller: Roller) { private val paperBundle by lazy { _paperBundle.get() } fun print() { paperBundle.getPaper() println("Printing.....") roller.rollPaper() } } Kuala Lumpur
92. class Printer @Inject constructor(private val roller: Roller) { private val paperBundle: PaperBundle by inject() fun print() { paperBundle.getPaper() println("Printing.....") roller.rollPaper() } } Kuala Lumpur
93. Kuala Lumpur Printer Roller +rollPaper() PaperBundle +canRollPaper() +setPaperRolled() +getPaper() PrinterRoller PaperTray
94. Kuala Lumpur Printer Roller +rollPaper() PaperBundle +canRollPaper() +setPaperRolled() +getPaper() PrinterRoller PaperTray
95. Kuala Lumpur Printer Roller +rollPaper() PaperBundle +canRollPaper() +setPaperRolled() +getPaper() PrinterRoller PaperTray
97. How to get android context? Kuala Lumpur
98. //Declaring dependencies val module = module { single { AppPreferences(androidApplication()) } Single { MyClass(androidContext())} } Kuala Lumpur
99. Let’s take a look at Scope API Kuala Lumpur
100. What is a Scope? A scope is context with fixed duration of time, in which an object exists. When the scope ends, any object bound under the scope cannot be injected again. Kuala Lumpur
101. Component’s lifetime Kuala Lumpur Container Single Factory Factory Factory Scope
102. Think it with boxes... Kuala Lumpur
103. Think it with boxes Kuala Lumpur Container Single Factory Factory Factory Scope
104. Components Kuala Lumpur Container Data Repository View View View User session
105. dependencies { def koinVersion = "2.0.1" // koin for android + scope feature implementation "org.koin:koin-android-scope:$koinVersion" } Kuala Lumpur
106. Scope val androidModule = module { } Kuala Lumpur
107. Scope val androidModule = module { scope { } } Kuala Lumpur
108. Scope val androidModule = module { scope(named("scope_id")) { } } Kuala Lumpur
109. Scope val androidModule = module { scope(named("scope_id")) { scoped { Presenter() } } } Kuala Lumpur
110. Scope scope(named("session")) { scoped { UserSession() } } Kuala Lumpur //create a session with id `ourSession` and qualifier `session` val ourSession = getKoin().createScope("ourSession",named("session")) //get session instance from scope val userSession : UserSession by ourSession.inject() //closing the scope ourSession.close()
111. Extensions for Android lifecycle + Koin scope Kuala Lumpur
112. Current scope val androidModule = module { scope(named<MyActivity>()) { scoped { Presenter() } } } Kuala Lumpur class MyActivity : AppCompatActivity() { // inject Presenter instance from current scope val presenter : Presenter by currentScope.inject()
113. Kuala Lumpur Ready for Android Architecture Components
114. dependencies { def koinVersion = "2.0.1" // koin for android + viewmodel feature implementation "org.koin:koin-android-viewmodel:$koinVersion" } Kuala Lumpur
115. Koin extensions for Android ViewModel Kuala Lumpur
116. View model class MyViewModel(val printer: Printer) : ViewModel() val viewModelModule = module { } Kuala Lumpur
117. View model class MyViewModel(val printer: Printer) : ViewModel() val viewModelModule = module { viewModel { } } Kuala Lumpur
118. View model class MyViewModel(val printer: Printer) : ViewModel() val viewModelModule = module { viewModel { MyViewModel(???) } } Kuala Lumpur
119. View model class MyViewModel(val printer: Printer) : ViewModel() val viewModelModule = module { viewModel { MyViewModel(get()) } } Kuala Lumpur
120. View model class DetailActivity : AppCompatActivity() { // Lazy inject ViewModel val detailViewModel: DetailViewModel by viewModel() // Eager inject ViewModel val detailViewModel: DetailViewModel = getViewModel() } Kuala Lumpur
121. Shared View model val viewModelModule = module { // PrinterViewModel declaration for Weather View components viewModel { PrinterViewModel(get(), get()) } } Kuala Lumpur
122. Shared View model class PrinterActivity : AppCompatActivity() { private val printerViewModel by viewModel<PrinterViewModel>() } class PrinterHeaderFragment : Fragment() { private val weatherViewModel by sharedViewModel<PrinterViewModel>() } class PrinterListFragment : Fragment() { private val weatherViewModel by sharedViewModel<PrinterViewModel>() } Kuala Lumpur
123. Tests Made Easy Kuala Lumpur
124. dependencies { def koinVersion = "2.0.1" // koin for tests testImplementation "org.koin:koin-test:$koinVersion" } Kuala Lumpur
125. class KoinTest { @Test fun `check all definitions of printer module`() { startKoin { } } } Kuala Lumpur
126. class KoinTest { @Test fun `check all definitions of printer module`() { startKoin { modules(printerModule) } } } Kuala Lumpur
127. class KoinTest { @Test fun `check all definitions of printer module`() { startKoin { modules(printerModule) }.checkModules() } } Kuala Lumpur
128. Koin extensions with junit and Mockito Kuala Lumpur
129. class PrinterTest: KoinTest { @Test fun `check roll paper status before and after print`() { startKoin { modules(printerModule) } } } Kuala Lumpur
130. class PrinterTest: KoinTest { private val printer: Printer by inject() private val paperBundle: PaperBundle by inject() @Test fun `check roll paper status before and after print`() { startKoin { modules(printerModule) } } } Kuala Lumpur
131. class PrinterTest: KoinTest { private val printer: Printer by inject() private val paperBundle: PaperBundle by inject() @Test fun `check roll paper status before and after print`() { startKoin { modules(printerModule) } declareMock<PaperBundle>() } } Kuala Lumpur
132. class PrinterTest: KoinTest { private val printer: Printer by inject() private val paperBundle: PaperBundle by inject() @Test fun `check roll paper status before and after print`() { startKoin { modules(printerModule) } declareMock<PaperBundle>() given(paperBundle.canRollPaper()).will { true } printer.print() } } Kuala Lumpur
133. class PrinterTest: KoinTest { private val printer: Printer by inject() private val paperBundle: PaperBundle by inject() @Test fun `check roll paper status before and after print`() { startKoin { modules(printerModule) } declareMock<PaperBundle>() given(paperBundle.canRollPaper()).will { true } printer.print() verify(paperBundle, times(1)).canRollPaper() verify(paperBundle, times(1)).setPaperRolled() } } Kuala Lumpur
134. class PrinterTest: KoinTest { private val printer: Printer by inject() private val paperBundle: PaperBundle by inject() @Test fun `check roll paper status before and after print`() { startKoin { modules(printerModule) } declareMock<PaperBundle>() given(paperBundle.canRollPaper()).will { true } printer.print() verify(paperBundle, times(1)).canRollPaper() verify(paperBundle, times(1)).setPaperRolled() } } Kuala Lumpur
135. Koin example https://github.com/TejaChirala/koinDemo Dagger example https://github.com/TejaChirala/daggerPrinter More details https://insert-koin.io/ Kuala Lumpur
136. Thank you Kuala Lumpur