How to choose the ORM on Android

I am the author of Orma. This presentation shows how Android ORMs are designed and how to choose your favorite. Enjoy ORMs!

Transcript

1. How to Choose the ORM on Android DroidKaigi 2017, day 2, 10:40-11:30 room 3 by goro-fuji@bitjourney.com (@__gfx__)  #DroidKaigi3
2. Table of Contents I. Introduction to the Speaker II. What ORMs Are III. Comparison of ORMs IV. How Orma Is Designed 
3. Table of Contents I. Introduction to the Speaker II. What ORMs Are III. Comparison of ORMs IV. How Orma Is Designed 
4. Introduction to the Speaker • Rails Engineer at Bit Jouryney, Inc. • Released Kibela (kibe.la) recently • Mobile Application Engineer at Speee, Inc. • As a Technical Advisor • Loves Programming, Cooking and Gaming 
5. 
6. Released Kibela at 2017/3/1 
7. Table of Contents I. Introduction to the Speaker II. What ORMs Are III. Comparison of ORMs IV. How Orma Is Designed 
8. Why You Stores Data to Local • To identify the device and its preferences • Much faster than Web API • Much more reliable than Web API 
9. Why You Stores Data to Local • To identify the device and its preferences • Much faster than Web API -> cache • Much more reliable than Web API -> offline-first development 
10. What You Stores to Storages • Preferences (or settings) • Caches • Drafts • Buffers (or queue) 
11. Data Storage on Android • Built-in SharedPreferences • Built-in File with the filesystem • Built-in SQLiteDatabase (SQLite) • SQLite wrappers (ORMs) • Original DB (Realm, ObjectBox, etc.) 
12. Data Storage on Android • Built-in SharedPreferences • Built-in File with the filesystem • Built-in SQLiteDatabase (SQLite) • SQLite wrappers (ORMs) • Original DB (Realm, ObjectBox, etc.) 
13. Built-in SQLiteDatabase • RDBMS • Interface to SQLite3 (C library) • Opetations with SQL (SQL-92) • Transactions 
14. ORMs • Object-Relation Mapper • Lots of implementations: • ActiveAndroid, DBFlow, Orma, Requery, ORMLite, greenDAO, SugarORM, StorIO, Realm, and etc. 
15. What ORMs do • O/R Mapping • Query Builder • Association Management • Publish / Subscribe (pub-sub) • Migration 
16. O/R Mapping deserialize↓↑serialize 
17. Query Builder • a.k.a. SQL builder • todos.equal(“title”, title) • todos.equal(Todo_Meta.title, title) • todos.titleEq(title) 
18. Query Builder • a.k.a. SQL builder • todos.equal(“title”, title) • todos.equal(Todo_Meta.title, title) • todos.titleEq(title) 
19. Query Builder • a.k.a. SQL builder • todos.equal(“title”, title) • todos.equal(Todo_Meta.title, title) • todos.titleEq(title) 
20. Query Builder • a.k.a. SQL builder • todos.equal(“title”, title) • todos.equal(Todo_Meta.title, title) • todos.titleEq(title) 
21. Association (or relathinship) • Handles table-to-table association • has-one / has-many / many-to-many 
22. Pub-Sub • Notifications on data-set changes • Used to synchronize model state • e.g. the state of “” over fragments 
23. Migration • How schema changes apply to the database • Calling ALTER TABLE, or completely re- create tables if needed • SQLiteOpenHelper’s / Java code / Automatic
24. What are ORMs? ✅ O/R Mapping ✅ Query Builder ✅ Associations ✅ Publish / Subscribe (pub-sub) ✅ Migration 
25. As Open Source Software • README / document • CI / CD • Number of comitters • Changelogs / relase notes • Recent activities
26. Table of Contents I. Introduction to the Speaker II. What ORMs Are III.Comparison of ORMs IV. How Orma Is Designed 
27. Comparison of ORMs • ActiveAndroid v3.0 • greenDAO v3.2.0 • Requery v1.2.0 • SQLBrite v0.6.2 & SQLDelight v0.6.0 • Realm v3.0.0 • Orma v4.2.1
28. What to See A. How O/R Mapping Is B. The Interface of Query Builder C. Association Support D. Pub-Sub Support E. Migration F. Performance G. As Open Source Software
29. ActiveAndroid v3.0
30. ActiveAndroid • One of the most famous ORM in Android • Considered as easy to use • No longer maintained • Baseline for many of ORMs • Based on reflection
31. Model Definition
32. Usage
33. Usage
34. Usage
35. Query Builder
36. Association
37. Association
38. Has-Many Association getMany() is useless because it returns List<T>
39. Pub-Sub: via ContentProvider The end of Model#save() method: ↓
40. Migration • In short: TERRIBLE • Just execute versioned SQL files • In development: you have to uninstall the app for each time you change the schema
41. As Open Source Software • Last commit: 2014/10 • The last stable version tag: 2012/01 • No longer maintained
42. Pros. and Cons. • Easy to setup / model / use • Not type safe • No longer maintained
43. greenDAO v3.2.0
44. greenDAO • One of the most famous ORM in Android • Considered as high performance • Modeling was considered terrible • Based on gradle-plugin-based code generator
45. Model Definition
46. Model Definition (after sync)
47. Usage
48. Usage
49. Usage
50. Query Builder
51. Query Builder
52. Query Builder
53. Association
54. Pub-Sub • Not supported
55. Migration • Not supported
56. As Open Source Software • Last commit: 2017/03 • Last stable release: 2016/10 • @greenbot is developing another ORM: • ObjectBox, a brand-new mobile database with source-code compatibility with greenDAO
57. Pros. and Cons. • Performance is awesome • Modifying source code seems really strange • Not so type safety • Migration is terrible
58. Requery v1.2.0
59. Requery • a brand-new ORM for Android • v1.0.0 is released at 2016/09 • Annotation-processor-based code generator
60. Model Definition ↓
61. Usage • DatabaseSouce extends SQLiteOpenHelper • Models is a generated class
62. Usage • DatabaseSouce extends SQLiteOpenHelper • Models is a generated class
63. Usage • DatabaseSouce extends SQLiteOpenHelper • Models is a generated class
64. Query Builder • where(Condition<V, ?>) • Todo.ID.eq(Integer)
65. Association
66. Pub-Sub • Supported with RxJava / RxJava2
67. Migration • Add new columns automatically • but need schemaVersion++ • Do nothing if constraints or the type change
68. As Open Source Software • Very active • Not so kind for Android developers • because it supports lots of databases
69. Pros. and Cons. • RxJava support seems cool • Too many abstraction • Supporting non-Android plarfotms are useless for us
70. SQLBright v0.6.2 & SQLDelight v0.6.0
71. SQLBrite & SQLDelight • Developed by Square • SQLBrite: pub-sub helper to SQLite • SQLDelgith: generates models from DSL
72. SQLDelgiht DSL That’s SQL
73. SQLDelgiht DSL That’s SQL !?
74. Pros. and Cons. • SQLBright is interesting if you use raw SQLiteOpenHelper • SQLDelight’s DSL is strange
75. Realm v3.0.0
76. Realm (realm-java) • A superstar of ORMs • Not based on SQLite • Developed by Realm
77. Model Definition
78. Usage
79. Query Builder • equalTo() is not type-safe
80. Association • Supported
81. Pub-Sub • Supported
82. Migration
83. Migration
84. Realm Mobile Platform • Synchronized data within multiple devices • See “Offline-First Application Development” in DroidKaigi 217 day 1 by zaki50
85. Pros. and Cons. • Users do not use generated classes, and thus the interface is not type safe • Full-time comitters are awesome • Migration is terrible • Query builder is not type safe
86. Table of Contents I. Introduction to the Speaker II. What ORMs are III. Comparison of ORMs IV. How Orma Is Designed 
87. Orma v4.2.1
88. Orma • v1.0.0 is released at 2016/01 • Used in cookpad, Abema TV, mercari atte, pairs, droidkaigi 2017 • annotation-processor based code generator
89. Model Definition • No base class • Explicit annotations required
90. Usage • Writing on ui-thread raises exceptions
91. Usage • Writing on ui-thread raises exceptions
92. Usage • Todo_Relation Todo_Relation#idEq(long)
93. Usage • Todo_Relation Todo_Relation#idEq(long)
94. Todo_Relation
95. Todo_Relation 5PEP@3FMBUJPO
    
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96. Todo_Relation 5PEP@3FMBUJPO
    
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97. Usage
98. Query Builder • Todo_Selector (generated class) • Todo_Selector#idEq(long) • only for indexed columns • Todo_Selector#orderByIdDesc() • only for indexed columns
99. Generated Code ↓ jump to definition
100. Association
101. Pu-Sub • Supported experimentally
102. Migration • schema-diff migration • ALTER TABLE from diff • step-by-step migration • hand-written steps
103. SchemaDiffMigration • Can detect • add columns / tables • delete columns • change the column constraints • Can’t: rename columns / tables
104. sqlite_master $ sqlite3 foo.db sqlite> create table foo(id integer primary key); sqlite> select * from sqlite_master; table|foo|foo|2|CREATE TABLE foo(id integer primary key) • DDL are available via sqlite_master
105. Versioning • Migration is triggered on SCHEMA_HASH is changed • SCHEMA_HASH = SHA256(DDL)
106. Pros. and Cons. • SchemaDiffMigration is awesome
107. Pros. and Cons. • SchemaDiffMigration is awesome • Type-safe query builder is awesome
108. Pros. and Cons. • SchemaDiffMigration is awesome • Type-safe query builder is awesome • Association is incubating
109. Pros. and Cons. • SchemaDiffMigration is awesome • Type-safe query builder is awesome • Association is incubating • pub-sub is incubating
110. Any Questions?