Realm is a new player on mobile database scene, and acts as a replacement for SQLite on Android and Core Data on iOS by providing a database and an easy-to-use object-relational mapping-like (ORM) interface. Learn how to use it in your own projects and how it compares to working with SQLite in a beginner-friendly sample app with Pokémon. This talk was presented at Droidcon Montreal on April 10th, 2015.

1. Gotta Persist ‘Em All:
Realm as Replacement
for SQLite
Siena Aguayo
Indiegogo
@dotheastro

2. Overview
● What Realm Is
● Pros and cons
● Compare and contrast with SQLite
● What Realm Isn’t

3. But First, Hello!

8. Realm Meetup
Drinkup + Roadmap
March 24th, 2015
San Francisco

9. What Realm Is

10. ● “embedded mobile database”
Realm
● Core is written in C++
● Available for Android and iOS
● Second most-deployed mobile database in
the world

11. Pros

12. Pros for Realm
● Very responsive team
● Easy to use
● Convenient for creating and storing data on
the fly
● Object conversion handled for you
● Faster than SQLite

13. Source: https://realm.io/news/realm-for-android/#realm-for-android

14. Source: https://realm.io/news/realm-for-android/#realm-for-android

15. Source: https://realm.io/news/realm-for-android/#realm-for-android

16. Cons

17. Cons for Realm
● Have to create with Java on the device
● Still under active development
● Not a lot of content online
● No importing
● Can’t access objects across threads

18. Missing Features
● Auto-incrementing ids
● Easy migrations (exist, but are painful)
● Compound primary keys
● Notifications on specific data changed
● Null support
● Testing with Robolectric
● Map<K, V> support

19. Compare and Contrast with SQLite

20. Database Connection
and Setup

21. Shipping with Existing Database
copy
SQLite: SQLiteAssetHelper
Realm: Sample migration app

22. Shipping with Existing Database
SQLite:
dbHelper.getReadableDatabase() or
dbHelper.getWritableDatabase()
Realm:
Realm.getInstance(context)

23. Creating Schema
SQLite

24. Creating Schema
Realm

25. No args constructor
Completely vanilla
getters and setters
NO custom logic in your models

26. In Realm, your models ARE your schema.

27. Reading Data

28. Java with SQLite

29. Find All
Java with Realm
Find First

30. Writing Data

31. Java with SQLite

32. Java with Realm

33. Java with Realm

34. Adding Relationships and
Complex Queries

35. Encounter has a LocationArea
LocationArea has a Location

36. Location
LocationAreaEncounter

37. Raw SQL

38. Java with Realm

40. What Realm Isn’t

41. Realm says they are not an ORM because
your data is not copied.

42. An ORM or not?
SQLite
>> pragma table_info(pokemon)
0|id|INTEGER|1||1
1|identifier|VARCHAR(79)|1||0
2|height|INTEGER|1||0
3|weight|INTEGER|1||0
Java
public class Pokemon {
private int id;
private String identifier;
private int height;
private int weight;
// constructor(s),
// getters, setters
}
Typical ORM usage

43. Data from Realm in the toString()...
Member variables are all uninitialized...

44. Shout-Out to Other ORMs
● greenDAO
● Active Android
● Sugar ORM
● ORMLite (Java)
● Cupboard
Michael Pardo’s Android Data talk

45. Conclusion

46. Acknowledgments
● Realm: http://realm.io/
● SQLite db from veekun’s Pokémon repo:
https://github.com/veekun/pokedex

47. Questions?
Twitter: @dotheastro