Clean up your data repository

A presentation about Architecture and how to keep your data layer organized.
Droidcon Turin 2019

Transcript

1. Copyright © 2019 Accenture All rights reserved. Avoid the mess! Clean up your data repository
2. Copyright © 2019 Accenture All rights reserved.
3. Copyright © 2019 Accenture All rights reserved.
4. Copyright © 2019 Accenture All rights reserved. Who we are Alessandro Recchi Antonello Fodde Android Software Engineer Android Software Engineer “One line of code, one ⌘ + ⌥ + L to clean it up” “Everything that Antonello says it’s probably wrong”
5. Copyright © 2019 Accenture All rights reserved. C I want this page to load faster. How can we do it? A C Sure. The page is pretty new and uses a modern architecture. Let’s put a DB as a cache. It will take no time Nice!
6. Copyright © 2019 Accenture All rights reserved.
7. Copyright © 2019 Accenture All rights reserved.
8. Copyright © 2019 Accenture All rights reserved. @Entity(indices = arrayOf( Index(value = arrayOf("uniqueKey"), unique = true ))) data class Entry( @PrimaryKey(autoGenerate = true) val entryId: Int, var uniqueKey: String?, var storeId: String?, @ColumnInfo(name = "entry_name") val name: String?, @JsonAdapter(StringFromUrlObjDeserializer::class) val image: String?, @ColumnInfo(name = "entry_code") var code: String?, @Embedded val color: Color?, val variants: List<Variant>?, @SerializedName("productMarker") @Embedded(prefix = "product_") val productMarker: Marker?, @SerializedName("showPrice") val showPriceMarker: Boolean, @Embedded(prefix = "ordinary_") val price: Price?, ) : AbstractComponentModel() { fun createUniqueIndex() { uniqueKey = code + "_" + storeId } } What went wrong...
9. Copyright © 2019 Accenture All rights reserved. @Entity(indices = arrayOf( Index(value = arrayOf("uniqueKey"), unique = true ))) data class Entry( @PrimaryKey(autoGenerate = true) val entryId: Int, var uniqueKey: String?, var storeId: String?, @ColumnInfo(name = "entry_name") val name: String?, @JsonAdapter(StringFromUrlObjDeserializer::class) val image: String?, @ColumnInfo(name = "entry_code") var code: String?, @Embedded val color: Color?, val variants: List<Variant>?, @SerializedName("productMarker") @Embedded(prefix = "product_") val productMarker: Marker?, @SerializedName("showPrice") val showPriceMarker: Boolean, @Embedded(prefix = "ordinary_") val price: Price?, ) : AbstractComponentModel() { fun createUniqueIndex() { uniqueKey = code + "_" + storeId } } Gson
10. Copyright © 2019 Accenture All rights reserved. @Entity(indices = arrayOf( Index(value = arrayOf("uniqueKey"), unique = true ))) data class Entry( @PrimaryKey(autoGenerate = true) val entryId: Int, var uniqueKey: String?, var storeId: String?, @ColumnInfo(name = "entry_name") val name: String?, @JsonAdapter(StringFromUrlObjDeserializer::class) val image: String?, @ColumnInfo(name = "entry_code") var code: String?, @Embedded val color: Color?, val variants: List<Variant>?, @SerializedName("productMarker") @Embedded(prefix = "product_") val productMarker: Marker?, @SerializedName("showPrice") val showPriceMarker: Boolean, @Embedded(prefix = "ordinary_") val price: Price?, ) : AbstractComponentModel() { fun createUniqueIndex() { uniqueKey = code + "_" + storeId } } Room
11. Copyright © 2019 Accenture All rights reserved. private fun deleteItemFromList(code: String) { repository.deleteItem(code) .observeOn(AndroidSchedulers.mainThread()) .subscribe({ myFavouriteRepository.deleteItemDB(code) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe({}, {}) }, {}) } Leaked responsibilities
12. Copyright © 2019 Accenture All rights reserved. Leaked responsibilities private fun deleteItemFromList(code: String) { repository.deleteItem(code) .observeOn(AndroidSchedulers.mainThread()) .subscribe({ myFavouriteRepository.deleteItemDB(code) .subscribeOn(Schedulers.io()) .observeOn(AndroidSchedulers.mainThread()) .subscribe({}, {}) }, {}) }
13. Copyright © 2019 Accenture All rights reserved. Separation of Concerns Principle “separation of concerns … even if not perfectly possible is yet the only available technique for effective ordering of one’s thoughts” Edsgar Dikjstra, 1974
14. Copyright © 2019 Accenture All rights reserved. The Clean Architecture “Good architecture makes the system easy to understand, easy to develop, easy to maintain, and easy to deploy” Robert C. Martin, Clean Architecture UI Controllers Use Case Entity Repository DB External interfaces Devices Web Presenters
15. Copyright © 2019 Accenture All rights reserved.
16. Copyright © 2019 Accenture All rights reserved. The Clean Architecture UI Controllers Use Case Entity Repository DB External interfaces Devices Web Presenters
17. Copyright © 2019 Accenture All rights reserved. The Clean Architecture UI Use Case Presenter DataSource Entity Repository
18. Copyright © 2019 Accenture All rights reserved. The Clean Architecture UI Use Case Presenter DataSource Entity Repository
19. Copyright © 2019 Accenture All rights reserved. The Clean Architecture UI Use Case Presenter DataSource Entity Repository
20. Copyright © 2019 Accenture All rights reserved. The Clean Architecture UI Use Case Presenter DataSource Entity Repository
21. Copyright © 2019 Accenture All rights reserved. Data Flow UI Use Case Presenter DataSource Entity Repository
22. Copyright © 2019 Accenture All rights reserved. Layers UI Presenter Use Case Entity Repository Data Source
23. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Layers Presentation MVVM View View Model Model
24. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Layers Presentation Domain MVVM View View Model Use Case Entity
25. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Layers Presentation Domain Data MVVM View View Model Use Case Entity Repository Remote Data Source Local Data Source Repository
26. Copyright © 2019 Accenture All rights reserved. Project Structure Domain Data Presentation
27. Copyright © 2019 Accenture All rights reserved. Project Structure Domain Presentation Data
28. Copyright © 2019 Accenture All rights reserved. Project Structure Feature 2 Feature 3 Feature 1
29. Copyright © 2019 Accenture All rights reserved. Feature 1 Project Structure Data Domain Presentation Screaming Architecture
30. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Dependency Rule “Nothing in an inner circle can know anything at all about something in an outer circle” Robert C. Martin, Clean Architecture
31. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Layers Presentation Domain Data MVVM View View Model Use Case Entity Repository Remote Data Source Local Data Source Repository
32. Copyright © 2019 Accenture All rights reserved. Inversion of Control Domain Use Case Data Repository
33. Copyright © 2019 Accenture All rights reserved. Inversion of Control Domain Use Case Repository Data RepositoryImpl Domain Use Case Data Repository
34. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Layers Presentation Domain Data MVVM View View Model Use Case Entity Repository Remote Data Source Local Data Source Repository
35. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Layers Presentation Domain Data MVVM View View Model Use Case Entity RepositoryImpl Remote Data Source Local Data Source Repository Repository
36. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Data Mappers Presentation Domain Data Network Model DB Model
37. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Data Mappers Presentation Domain Data Domain Model Domain Model asDomainModel Network Model DB Model
38. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Data Mappers Presentation Domain Data Domain Model UI Model Domain Model UI Model asDomainModel asUIModel Network Model DB Model
39. Copyright © 2019 Accenture All rights reserved. “O Software Architect, you must see the future. You must guess-intelligently. You must weigh the costs and determine where the architectural boundaries lie, and which should be fully implemented, and which should be partially implemented, and which should be ignored.” Robert C. Martin, Clean Architecture
40. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Layers Presentation Domain Data MVVM View View Model Use Case Entity Repository Remote Data Source Local Data Source Repository
41. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Layers Presentation Domain Data MVVM View View Model Use Case Entity Repository Remote Data Source Local Data Source Repository
42. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Layers Presentation Domain Data MVVM View View Model Use Case Entity Repository Remote Data Source Local Data Source Repository
43. Copyright © 2019 Accenture All rights reserved. UI Presenter Use Case Entity Repository Data Source Layers Presentation Domain Data MVVM View View Model Use Case Entity Repository Remote Data Source Local Data Source Repository
44. Copyright © 2019 Accenture All rights reserved. Data Layer Data Repository Remote Data Source Local Data Source Repository
45. Copyright © 2019 Accenture All rights reserved. Data Layer Data Repository Remote Data Source Local Data Source Repository
46. Copyright © 2019 Accenture All rights reserved. Data Layer Data Repository Remote Data Source Local Data Source Repository
47. Copyright © 2019 Accenture All rights reserved. Single Source of Truth Single Source of Truth, in short SSOT, refers to the concept where certain data has only one official source to be used by data consumers (i.e. humans and software) for the true current version of that data. Source: https://www.dragon1.com/concepts/single-source-of-truth
48. Copyright © 2019 Accenture All rights reserved. Showcase App ?
49. Copyright © 2019 Accenture All rights reserved. How do you keep up to date?
50. Copyright © 2019 Accenture All rights reserved. How do you keep up to date?
51. Copyright © 2019 Accenture All rights reserved. How do you keep up to date?
52. Copyright © 2019 Accenture All rights reserved. Jakebook Showcase App
53. Copyright © 2019 Accenture All rights reserved. WANT TO BE UPDATED ABOUT ALL JAKE ONLINE ACTIVITIES? YOU WILL NEVER MISS A SINGLE JAKE QUOTE! Showcase App Jakebook “I love Jake!” by @lollipop.lover77 “thanks to this app I became a better developer!” by @honeycomb “The app crashes on Android 9…” by @PisForPankakes
54. Copyright © 2019 Accenture All rights reserved. class TwitterDataSourceImpl @Inject constructor(private val twitterService: TwitterService) : TwitterDataSource override fun getTimeline(firstTweetId: Long?, lastTweetId: Long?, pageSize: Int?): Single<List<Feed>> { } } Single Remote Data Source
55. Copyright © 2019 Accenture All rights reserved. class TwitterDataSourceImpl @Inject constructor(private val twitterService: TwitterService) : TwitterDataSource override fun getTimeline(firstTweetId: Long?, lastTweetId: Long?, pageSize: Int?): Single<List<Feed>> { return twitterService .getUserTimeline(...) } } Single Remote Data Source
56. Copyright © 2019 Accenture All rights reserved. class TwitterDataSourceImpl @Inject constructor(private val twitterService: TwitterService) : TwitterDataSource override fun getTimeline(firstTweetId: Long?, lastTweetId: Long?, pageSize: Int?): Single<List<Feed>> { return twitterService .getUserTimeline(...) } } Single Remote Data Source
57. Copyright © 2019 Accenture All rights reserved. @GET("https://api.twitter.com/1.1/statuses/user_timeline.json") fun getUserTimeline( @Header("Authorization") auth: String, @Query("screen_name") name: String? = null, @Query("count") totalResults: Int? = null, @Query("max_id") resultFromId: Long? = null, @Query("since_id") resultBeforeId: Long? = null ): Single<List<TwitterUserTimelineItem>> Single Remote Data Source
58. Copyright © 2019 Accenture All rights reserved. @GET("https://api.twitter.com/1.1/statuses/user_timeline.json") fun getUserTimeline( @Header("Authorization") auth: String, @Query("screen_name") name: String? = null, @Query("count") totalResults: Int? = null, @Query("max_id") resultFromId: Long? = null, @Query("since_id") resultBeforeId: Long? = null ): Single<List<TwitterUserTimelineItem>> Single Remote Data Source
59. Copyright © 2019 Accenture All rights reserved. Single Remote Data Source data class TwitterUserTimelineItem( val id: Long, val created_at: String?, val text: String?, val user: User? ) data class Feed( val id: String, val image: String, val name: String, val content: String, val date: Date, val source: FeedSource ) TwitterUserTimelineItem.asDomainModel() Domain Data
60. Copyright © 2019 Accenture All rights reserved. Single Remote Data Source fun TwitterUserTimelineItem.asDomainModel() = Feed( id = "twitter_$id", image = user?.profile_image_url_https ?: "", name = user?.screen_name ?: "", content = text ?: "", date = created_at?.let { TWITTER_DATE_FORMAT.parse(it) } ?: Date(0), source = TWITTER ) Domain Data
61. Copyright © 2019 Accenture All rights reserved. class TwitterDataSourceImpl @Inject constructor(private val twitterService: TwitterService) : TwitterDataSource override fun getTimeline(firstTweetId: Long?, lastTweetId: Long?, pageSize: Int?): Single<List<Feed>> { return twitterService .getUserTimeline(...) } } Single Remote Data Source
62. Copyright © 2019 Accenture All rights reserved. class TwitterDataSourceImpl @Inject constructor(private val twitterService: TwitterService) : TwitterDataSource override fun getTimeline(firstTweetId: Long?, lastTweetId: Long?, pageSize: Int?): Single<List<Feed>> { return twitterService .getUserTimeline(...) .map { list -> list.map { it.asDomainModel() } } } } Single Remote Data Source
63. Copyright © 2019 Accenture All rights reserved. Single Remote Data Source class SingleSourceFeedRepository @Inject constructor( private val twitterRemoteDataSource: TwitterDataSource, private val roomLocalDataSource: LocalDataSource ) : FeedRepository() { override fun getFeed(): Flowable<List<Feed>> { refreshFeed() return roomLocalDataSource.getFeed() } override fun refreshFeed() { twitterRemoteDataSource.getTimeline() .subscribe({ roomLocalDataSource.insertFeeds(it) }, { ... }).bindToLifecycle(this) } }
64. Copyright © 2019 Accenture All rights reserved. Single Remote Data Source class SingleSourceFeedRepository @Inject constructor( private val twitterRemoteDataSource: TwitterDataSource, private val roomLocalDataSource: LocalDataSource ) : FeedRepository() { override fun getFeed(): Flowable<List<Feed>> { refreshFeed() return roomLocalDataSource.getFeed() } override fun refreshFeed() { twitterRemoteDataSource.getTimeline() .subscribe({ roomLocalDataSource.insertFeeds(it) }, { ... }).bindToLifecycle(this) } }
65. Copyright © 2019 Accenture All rights reserved. Single Remote Data Source class SingleSourceFeedRepository @Inject constructor( private val twitterRemoteDataSource: TwitterDataSource, private val roomLocalDataSource: LocalDataSource ) : FeedRepository() { override fun getFeed(): Flowable<List<Feed>> { refreshFeed() return roomLocalDataSource.getFeed() } override fun refreshFeed() { twitterRemoteDataSource.getTimeline() .subscribe({ roomLocalDataSource.insertFeeds(it) }, { ... }).bindToLifecycle(this) } }
66. Copyright © 2019 Accenture All rights reserved. Single Remote Data Source class SingleSourceFeedRepository @Inject constructor( private val twitterRemoteDataSource: TwitterDataSource, private val roomLocalDataSource: LocalDataSource ) : FeedRepository() { override fun refreshFeed() { ... } }
67. Copyright © 2019 Accenture All rights reserved. class DoubleSourceFeedRepository @Inject constructor( private val twitterRemoteDataSource: TwitterDataSource, private val gitHubRemoteDataSource: GitHubDataSource, private val roomLocalDataSource: LocalDataSource ) : FeedRepository() { override fun refreshFeed() { ... } } Double Remote Data Source
68. Copyright © 2019 Accenture All rights reserved. class DoubleSourceFeedRepository @Inject constructor( private val twitterRemoteDataSource: TwitterDataSource, private val gitHubRemoteDataSource: GitHubDataSource, private val roomLocalDataSource: LocalDataSource ) : FeedRepository() { override fun refreshFeed() { Single.zip( twitterRemoteDataSource.getTimeline(), gitHubRemoteDataSource.getPage(), BiFunction<List<Feed>, List<Feed>, List<Feed>> { twitterFeeds, githubFeeds -> twitterFeeds.plus(githubFeeds) }) .subscribe({ roomLocalDataSource.insertFeeds(it) }, { ... }).bindToLifecycle(this) } } Double Remote Data Source
69. Copyright © 2019 Accenture All rights reserved. class DoubleSourceFeedRepository @Inject constructor( private val twitterRemoteDataSource: TwitterDataSource, private val gitHubRemoteDataSource: GitHubDataSource, private val roomLocalDataSource: LocalDataSource ) : FeedRepository() { override fun refreshFeed() { Single.zip( twitterRemoteDataSource.getTimeline(), gitHubRemoteDataSource.getPage(), BiFunction<List<Feed>, List<Feed>, List<Feed>> { twitterFeeds, githubFeeds -> twitterFeeds.plus(githubFeeds) }) .subscribe({ roomLocalDataSource.insertFeeds(it) }, { ... }).bindToLifecycle(this) } } Double Remote Data Source
70. Copyright © 2019 Accenture All rights reserved. class DoubleSourceFeedRepository @Inject constructor( private val twitterRemoteDataSource: TwitterDataSource, private val gitHubRemoteDataSource: GitHubDataSource, private val roomLocalDataSource: LocalDataSource ) : FeedRepository() { override fun refreshFeed() { Single.zip( twitterRemoteDataSource.getTimeline(), gitHubRemoteDataSource.getPage(), BiFunction<List<Feed>, List<Feed>, List<Feed>> { twitterFeeds, githubFeeds -> twitterFeeds.plus(githubFeeds) }) .subscribe({ roomLocalDataSource.insertFeeds(it) }, { ... }).bindToLifecycle(this) } } Double Remote Data Source
71. Copyright © 2019 Accenture All rights reserved. ? What about paged resources
72. Copyright © 2019 Accenture All rights reserved. Paging Library
73. Copyright © 2019 Accenture All rights reserved.
74. Copyright © 2019 Accenture All rights reserved.
75. Copyright © 2019 Accenture All rights reserved. class TwitterPagedDataSource @Inject constructor(twitterService: TwitterService) : ItemKeyedDataSource<String, Feed>(), TwitterDataSource by TwitterDataSourceImpl(twitterService) { override fun loadInitial(params: LoadInitialParams<String>, callback: LoadInitialCallback<Feed>) { } override fun loadAfter(params: LoadParams<String>, callback: LoadCallback<Feed>) { } override fun loadBefore(params: LoadParams<String>, callback: LoadCallback<Feed>) { } } Paged Data Source
76. Copyright © 2019 Accenture All rights reserved. class TwitterPagedDataSource @Inject constructor(twitterService: TwitterService) : ItemKeyedDataSource<String, Feed>(), TwitterDataSource by TwitterDataSourceImpl(twitterService) { override fun loadInitial(params: LoadInitialParams<String>, callback: LoadInitialCallback<Feed>) { } override fun loadAfter(params: LoadParams<String>, callback: LoadCallback<Feed>) { } override fun loadBefore(params: LoadParams<String>, callback: LoadCallback<Feed>) { } } Paged Data Source
77. Copyright © 2019 Accenture All rights reserved. class TwitterPagedDataSource @Inject constructor(twitterService: TwitterService) : ItemKeyedDataSource<String, Feed>(), TwitterDataSource by TwitterDataSourceImpl(twitterService) { override fun loadInitial(params: LoadInitialParams<String>, callback: LoadInitialCallback<Feed>) { remoteCall(params, callback) } override fun loadAfter(params: LoadParams<String>, callback: LoadCallback<Feed>) { remoteCall(params, callback) } override fun loadBefore(params: LoadParams<String>, callback: LoadCallback<Feed>) { remoteCall(params, callback) } } Paged Data Source
78. Copyright © 2019 Accenture All rights reserved. class RemotePagedRepository @Inject constructor( private val twitterPagedDataSource: TwitterPagedDataSource ) : PagedRepository() { override fun getPagedFeed(): LiveData<PagedList<Feed>> = object : DataSource.Factory<String, Feed>() { override fun create(): DataSource<String, Feed> = twitterPagedDataSource } .toLiveData(config) } Paged Data Source
79. Copyright © 2019 Accenture All rights reserved. class RemotePagedRepository @Inject constructor( private val twitterPagedDataSource: TwitterPagedDataSource ) : PagedRepository() { override fun getPagedFeed(): LiveData<PagedList<Feed>> = object : DataSource.Factory<String, Feed>() { override fun create(): DataSource<String, Feed> = twitterPagedDataSource } .toLiveData(config) } Paged Data Source
80. Copyright © 2019 Accenture All rights reserved. Paged Data Source
81. Copyright © 2019 Accenture All rights reserved. class RemotePagedRepository @Inject constructor( private val twitterPagedDataSource: TwitterPagedDataSource ) : PagedRepository() { override fun getPagedFeed(): LiveData<PagedList<Feed>> = object : DataSource.Factory<String, Feed>() { override fun create(): DataSource<String, Feed> = twitterPagedDataSource } .toLiveData(config) } Paged Data Source
82. Copyright © 2019 Accenture All rights reserved. class RemotePagedRepository @Inject constructor( private val twitterPagedDataSource: TwitterPagedDataSource ) : PagedRepository() { override fun <O> getPagedFeed(mapper: (Feed) -> (O)): LiveData<PagedList<O>> = object : DataSource.Factory<String, Feed>() { override fun create(): DataSource<String, Feed> = twitterPagedDataSource }.map { i -> mapper.invoke(i) } .toLiveData(config) } Paged Data Source
83. Copyright © 2019 Accenture All rights reserved. abstract class PagedViewModel constructor(pagedRepository: PagedRepository) : LifecycleViewModel() { val pagedFeed: LiveData<PagedList<UIFeedItem>> = pagedRepository.getPagedFeed { it.asUIModel() } } Paged Data Source
84. Copyright © 2019 Accenture All rights reserved. abstract class PagedViewModel constructor(pagedRepository: PagedRepository) : LifecycleViewModel() { val pagedFeed: LiveData<PagedList<UIFeedItem>> = pagedRepository.getPagedFeed { it.asUIModel() } } Paged Data Source
85. Copyright © 2019 Accenture All rights reserved. ? Can we apply SSOT here
86. Copyright © 2019 Accenture All rights reserved. Paging with Room @Dao interface RoomFeedDao { @Query("SELECT * FROM feed ORDER BY date desc") fun getFeed(): Flowable<List<RoomFeed>> @Query("SELECT * FROM feed ORDER BY date desc") fun getAllPaged(): DataSource.Factory<Int, RoomFeed> @Query("DELETE FROM feed") fun deleteAll() @Insert(onConflict = OnConflictStrategy.IGNORE) fun insertFeed(feed: RoomFeed) @Insert(onConflict = OnConflictStrategy.IGNORE) fun insertFeedList(data: List<RoomFeed>?) } interface LocalDataSource { fun getFeed(): Flowable<List<Feed>> fun insertFeeds(list: List<Feed>) fun getPagedFeeds(): DataSource.Factory<Int, Feed> }
87. Copyright © 2019 Accenture All rights reserved. interface LocalDataSource { fun getFeed(): Flowable<List<Feed>> fun insertFeeds(list: List<Feed>) fun getPagedFeeds(): DataSource.Factory<Int, Feed> } Paging with Room @Dao interface RoomFeedDao { @Query("SELECT * FROM feed ORDER BY date desc") fun getFeed(): Flowable<List<RoomFeed>> @Query("SELECT * FROM feed ORDER BY date desc") fun getAllPaged(): DataSource.Factory<Int, RoomFeed> @Query("DELETE FROM feed") fun deleteAll() @Insert(onConflict = OnConflictStrategy.IGNORE) fun insertFeed(feed: RoomFeed) @Insert(onConflict = OnConflictStrategy.IGNORE) fun insertFeedList(data: List<RoomFeed>?) }
88. Copyright © 2019 Accenture All rights reserved. class LocalPagedRepository @Inject constructor( private val twitterRemoteDataSource: TwitterDataSource, private val roomLocalDataSource: LocalDataSource ) : PagedRepository() { override fun <O> getPagedFeed(mapper: (Feed) -> (O)): LiveData<PagedList<O>> { return roomLocalDataSource.getPagedFeeds() } } Paging with Room
89. Copyright © 2019 Accenture All rights reserved. class LocalPagedRepository @Inject constructor( private val twitterRemoteDataSource: TwitterDataSource, private val roomLocalDataSource: LocalDataSource ) : PagedRepository() { override fun <O> getPagedFeed(mapper: (Feed) -> (O)): LiveData<PagedList<O>> { return roomLocalDataSource.getPagedFeeds() .map { i -> mapper.invoke(i) } .toLiveData( config) } } Paging with Room
90. Copyright © 2019 Accenture All rights reserved. class LocalPagedRepository @Inject constructor( private val twitterRemoteDataSource: TwitterDataSource, private val roomLocalDataSource: LocalDataSource ) : PagedRepository() { override fun <O> getPagedFeed(mapper: (Feed) -> (O)): LiveData<PagedList<O>> { return roomLocalDataSource.getPagedFeeds() .map { i -> mapper.invoke(i) } .toLiveData( config, boundaryCallback = object : PagedList.BoundaryCallback<O>() { } ) } } Paging with Room
91. Copyright © 2019 Accenture All rights reserved. class LocalPagedRepository @Inject constructor( private val twitterRemoteDataSource: TwitterDataSource, private val roomLocalDataSource: LocalDataSource ) : PagedRepository() { override fun <O> getPagedFeed(mapper: (Feed) -> (O)): LiveData<PagedList<O>> { return roomLocalDataSource.getPagedFeeds() .map { i -> mapper.invoke(i) } .toLiveData( config, boundaryCallback = object : PagedList.BoundaryCallback<O>() { override fun onZeroItemsLoaded() { fetchNextFeed() } override fun onItemAtEndLoaded(lastItem: O) { fetchNextFeed(lastFeedId) } } ) } } Paging with Room
92. Copyright © 2019 Accenture All rights reserved. ? Is the paging library clean
93. Copyright © 2019 Accenture All rights reserved. Give us the code https://github.com/alerecchi/droidcon-clean-repository Jakebook Repository:
94. Copyright © 2019 Accenture All rights reserved. Get Connected https://twitter.com/_alerecchi https://twitter.com/m3rcvp https://github.com/alerecchi https://github.com/M3rcur14l
95. Copyright © 2019 Accenture All rights reserved. WE ARE HIRING!
96. Copyright © 2019 Accenture All rights reserved. THANK YOU