Data Persistence in Android with Room Library
1 like1,333 views
The document discusses data persistence in Android using the Room library, highlighting its benefits over previous solutions, such as reduced boilerplate code and improved testing capabilities. It explains the structure of Room including Entities, DAOs, and the handling of data migrations. Key takeaways include the requirement for explicit data requests and the limitations on object references between entity classes.
Data Persistence in Android with Room Library
- 1. Data persistence in Android with Room library Dmitry Dogar, Android developer
- 3. World before Room • Boilerplate code
- 4. World before Room • Boilerplate code
- 5. World before Room •Difficult migrations
- 6. World before Room •Difficult migrations
- 7. World before Room • Hard to test
- 8. Solutions 3d-party ORM libraries over SQLite like: • DBFlow • Requery • GreenDAO • And so on, many of them!
- 9. Solutions …OR even replacement for SQLite like
- 10. Google I/O 2017
- 11. Adding to project Release notes: 1.0.0 - November 6, 2017
- 12. Room structure
- 13. Entity
- 14. Entity Note: need getters & setters, not support for Lombok, AutoValue
- 15. Another Entity
- 16. Relation Object references - not supported From doc - Key takeaway: Room disallows object references between entity classes. Instead, you must explicitly request the data that your app needs.
- 17. Relation
- 18. Embedding
- 19. Data types Date - unknown type, requires converting
- 20. Data types Should be added to database object
- 21. Database object
- 22. Database object
- 23. DAO • QUERY • INSERT • UPDATE • DELETE
- 24. DAO - Need to write SQL queries, not typical for ORMs - Retrofit style
- 25. DAO
- 26. DAO - code generation
- 27. DAO - code generation
- 28. DAO - Threading • QUERY • INSERT • UPDATE • DELETE All Synchronous
- 29. DAO - Threading • QUERY • INSERT • UPDATE • DELETE All Synchronous Caused by: java.lang.IllegalStateException: Cannot access database on the main thread since it may potentially lock the UI for a long periods of time.
- 30. DAO - Threading Quick, but not good fix
- 31. DAO - LiveData
- 32. DAO - RxJava
- 33. DAO - RxJava
- 34. DAO - RxJava
- 35. DAO - RxJava
- 36. DAO - Query, Joins @Dao public interface MyDao { @Query("SELECT * FROM book " + "INNER JOIN loan ON loan.book_id = book.id " + "INNER JOIN user ON user.id = loan.user_id " + "WHERE user.name LIKE :userName") public List<Book> findBooksBorrowedByNameSync(String userName); } From official documentation:
- 37. DAO - Query, Joins Another way:
- 38. DAO - Query, Joins Another way:
- 39. DAO - Query, Joins Another way:
- 40. Testing
- 41. Testing
- 42. Testing
- 43. Testing
- 44. Testing RxJava’s Flowable Similar with LiveData
- 45. Testing More real-life example UnitTest
- 46. Testing More real-life example UnitTest
- 47. Migrations
- 48. Migrations
- 49. Migrations
- 53. Migrations Provide migration Add it to db object
- 57. Migrations Testing Setup • Turn on schema export (as json file) • In build.gradle: Set schema location to tests • Export schema for annotation processor
- 58. Migrations Testing @RunWith(AndroidJUnit4.class) public class MigrationTest { private static final String TEST_DB_NAME = “test_employee_db”; @Rule public MigrationTestHelper helper; public MigrationTest() { helper = new MigrationTestHelper(InstrumentationRegistry.getInstrumentation(), EmployeesDatabase.class.getCanonicalName(), new FrameworkSQLiteOpenHelperFactory()); }
- 59. Migrations Testing @Test public void migrate1To2() throws IOException { SupportSQLiteDatabase db = helper.createDatabase(TEST_DB_NAME, 1); insertEmployee(db); // need to insert with ContentValues SQLIte API helper.runMigrationsAndValidate(TEST_DB_NAME, 2, true, MIGRATION_1_2); And then build db object, get Data from DAO and write asserts
- 60. Summary • Removes ugly boilerplate low level APIs code • Google support • Nice testing and RxJava2 support • Use it if you need it
- 61. Links • https://medium.com/@florina.muntenescu Florina Muntenescu blogs Aleksander Piotrowski, Talk at GDGDevFest 2017 Is there a room for Room? • https://www.youtube.com/watch?v=BHiKSnOaoh4 • https://goo.gl/dNYY3S Florina Muntenescu talk at realm.io And official doc • https://developer.android.com/training/data-storage/room/index.html
- 62. Thank you!