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
   

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2. Table of Contents
   I. Introduction to the Speaker
   II. What ORMs Are
   III. Comparison of ORMs
   IV. How Orma Is Designed
   
   

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3. Table of Contents
   I. Introduction to the Speaker
   II. What ORMs Are
   III. Comparison of ORMs
   IV. How Orma Is Designed
   
   

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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
   
   

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5. 
   

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6. Released Kibela at 2017/3/1
   
   

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7. Table of Contents
   I. Introduction to the Speaker
   II. What ORMs Are
   III. Comparison of ORMs
   IV. How Orma Is Designed
   
   

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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
   
   

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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
   
   

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10. What You Stores to Storages
    • Preferences (or settings)
    • Caches
    • Drafts
    • Buffers (or queue)
    
    

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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.)
    
    

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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.)
    
    

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13. Built-in SQLiteDatabase
    • RDBMS
    • Interface to SQLite3 (C library)
    • Opetations with SQL (SQL-92)
    • Transactions
    
    

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14. ORMs
    • Object-Relation Mapper
    • Lots of implementations:
    • ActiveAndroid, DBFlow, Orma,
    Requery, ORMLite, greenDAO,
    SugarORM, StorIO, Realm, and etc.
    
    

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15. What ORMs do
    • O/R Mapping
    • Query Builder
    • Association Management
    • Publish / Subscribe (pub-sub)
    • Migration
    
    

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16. O/R Mapping
    deserialize↓↑serialize
    
    

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17. Query Builder
    • a.k.a. SQL builder
    • todos.equal(“title”, title)
    • todos.equal(Todo_Meta.title, title)
    • todos.titleEq(title)
    
    

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18. Query Builder
    • a.k.a. SQL builder
    • todos.equal(“title”, title)
    • todos.equal(Todo_Meta.title, title)
    • todos.titleEq(title)
    
    

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19. Query Builder
    • a.k.a. SQL builder
    • todos.equal(“title”, title)
    • todos.equal(Todo_Meta.title, title)
    • todos.titleEq(title)
    
    

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20. Query Builder
    • a.k.a. SQL builder
    • todos.equal(“title”, title)
    • todos.equal(Todo_Meta.title, title)
    • todos.titleEq(title)
    
    

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21. Association (or relathinship)
    • Handles table-to-table association
    • has-one / has-many / many-to-many
    
    

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22. Pub-Sub
    • Notifications on data-set changes
    • Used to synchronize model state
    • e.g. the state of “” over fragments
    
    

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23. Migration
    • How schema changes apply to the
    database
    • Calling ALTER TABLE, or completely re-
    create tables if needed
    • SQLiteOpenHelper’s / Java code /
    Automatic
    

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24. What are ORMs?
    ✅ O/R Mapping
    ✅ Query Builder
    ✅ Associations
    ✅ Publish / Subscribe (pub-sub)
    ✅ Migration
    
    

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25. As Open Source Software
    • README / document
    • CI / CD
    • Number of comitters
    • Changelogs / relase notes
    • Recent activities
    

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26. Table of Contents
    I. Introduction to the Speaker
    II. What ORMs Are
    III.Comparison of ORMs
    IV. How Orma Is Designed
    
    

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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
    

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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
    

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29. ActiveAndroid v3.0
    

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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
    

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31. Model Definition
    

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32. Usage
    

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33. Usage
    

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34. Usage
    

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35. Query Builder
    

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36. Association
    

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37. Association
    

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38. Has-Many Association
    getMany() is useless because it returns List
    

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39. Pub-Sub: via ContentProvider
    The end of Model#save() method:
    ↓
    

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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
    

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41. As Open Source Software
    • Last commit: 2014/10
    • The last stable version tag: 2012/01
    • No longer maintained
    

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42. Pros. and Cons.
    •
    Easy to setup / model / use
    •
    Not type safe
    •
    No longer maintained
    

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43. greenDAO v3.2.0
    

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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
    

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45. Model Definition
    

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46. Model Definition (after sync)
    

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47. Usage
    

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48. Usage
    

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49. Usage
    

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50. Query Builder
    

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51. Query Builder
    

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52. Query Builder
    

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53. Association
    

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54. Pub-Sub
    • Not supported
    

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55. Migration
    • Not supported
    

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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
    

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57. Pros. and Cons.
    •
    Performance is awesome
    •
    Modifying source code seems
    really strange
    • Not so type safety
    •
    Migration is terrible
    

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58. Requery v1.2.0
    

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59. Requery
    • a brand-new ORM for Android
    • v1.0.0 is released at 2016/09
    • Annotation-processor-based code
    generator
    

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60. Model Definition
    ↓
    

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61. Usage
    • DatabaseSouce extends SQLiteOpenHelper
    • Models is a generated class
    

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62. Usage
    • DatabaseSouce extends SQLiteOpenHelper
    • Models is a generated class
    

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63. Usage
    • DatabaseSouce extends SQLiteOpenHelper
    • Models is a generated class
    

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64. Query Builder
    • where(Condition)
    • Todo.ID.eq(Integer)
    

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65. Association
    

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66. Pub-Sub
    • Supported with RxJava / RxJava2
    

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67. Migration
    • Add new columns automatically
    • but need schemaVersion++
    • Do nothing if constraints or the type
    change
    

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68. As Open Source Software
    • Very active
    • Not so kind for Android developers
    • because it supports lots of
    databases
    

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69. Pros. and Cons.
    •
    RxJava support seems cool
    •
    Too many abstraction
    •
    Supporting non-Android
    plarfotms are useless for us
    

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70. SQLBright v0.6.2
    &
    SQLDelight v0.6.0
    

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71. SQLBrite & SQLDelight
    • Developed by Square
    • SQLBrite: pub-sub helper to SQLite
    • SQLDelgith: generates models from
    DSL
    

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72. SQLDelgiht DSL
    That’s SQL
    

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73. SQLDelgiht DSL
    That’s SQL
    !?
    

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74. Pros. and Cons.
    •
    SQLBright is interesting if you
    use raw SQLiteOpenHelper
    •
    SQLDelight’s DSL is strange
    

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75. Realm v3.0.0
    

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76. Realm (realm-java)
    • A superstar of ORMs
    • Not based on SQLite
    • Developed by Realm
    

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77. Model Definition
    

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78. Usage
    

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79. Query Builder
    • equalTo() is not type-safe
    

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80. Association
    • Supported
    

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81. Pub-Sub
    • Supported
    

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82. Migration
    

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83. Migration
    

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84. Realm Mobile Platform
    • Synchronized data within multiple
    devices
    • See “Offline-First Application
    Development” in DroidKaigi 217
    day 1 by zaki50
    

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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
    

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86. Table of Contents
    I. Introduction to the Speaker
    II. What ORMs are
    III. Comparison of ORMs
    IV. How Orma Is Designed
    
    

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87. Orma v4.2.1
    

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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
    

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89. Model Definition
    • No base class
    • Explicit annotations required
    

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90. Usage
    • Writing on ui-thread raises exceptions
    

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91. Usage
    • Writing on ui-thread raises exceptions
    

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92. Usage
    • Todo_Relation Todo_Relation#idEq(long)
    

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93. Usage
    • Todo_Relation Todo_Relation#idEq(long)
    

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94. Todo_Relation
    

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95. Todo_Relation
    5PEP@3FMBUJPO
    
    DPOUFOU&R lCBSz
    
    

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96. Todo_Relation
    5PEP@3FMBUJPO
    
    DPOUFOU&R lGPPz
    
    5PEP@3FMBUJPO
    
    DPOUFOU&R lCBSz
    
    

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97. Usage
    

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98. Query Builder
    • Todo_Selector (generated class)
    • Todo_Selector#idEq(long)
    • only for indexed columns
    • Todo_Selector#orderByIdDesc()
    • only for indexed columns
    

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99. Generated Code
    ↓ jump to definition
    

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100. Association
     

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101. Pu-Sub
     • Supported experimentally
     

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102. Migration
     • schema-diff migration
     • ALTER TABLE from diff
     • step-by-step migration
     • hand-written steps
     

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103. SchemaDiffMigration
     • Can detect
     • add columns / tables
     • delete columns
     • change the column constraints
     • Can’t: rename columns / tables
     

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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
     

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105. Versioning
     • Migration is triggered on
     SCHEMA_HASH is changed
     • SCHEMA_HASH = SHA256(DDL)
     

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106. Pros. and Cons.
     •
     SchemaDiffMigration is awesome
     

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107. Pros. and Cons.
     •
     SchemaDiffMigration is awesome
     •
     Type-safe query builder is awesome
     

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108. Pros. and Cons.
     •
     SchemaDiffMigration is awesome
     •
     Type-safe query builder is awesome
     •
     Association is incubating
     

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109. Pros. and Cons.
     •
     SchemaDiffMigration is awesome
     •
     Type-safe query builder is awesome
     •
     Association is incubating
     •
     pub-sub is incubating
     

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110. Any Questions?
     

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