When SQLite is not enough - Realm database

Quick introduction to Realm database on Android.

Transcript

1. When SQLite is not enough - Realm database Michał Moczulski @moczul
2. Agenda • Realm • Installation • Models • Object creation • Internals • Queries • Relationships • Sample app • Summary
3. Realm • Mobile oriented database • Android and iOS support • Simple API (no ORM needed!) • Memory efficient • Realm browser • Since 2011
4. Installation dependencies { compile 'io.realm:realm-android:0.71.0' ... }
5. Models public class Place extends RealmObject { @Index private String name; private double lat; private double lng; @Ignore private String description; public void setName(String name) { this.name = name; } public String getName() { return name; } }
6. Object creation Realm realm = Realm.getInstance(getBaseContext()); realm.beginTransaction(); for (Item item : items) { Place place = realm.createObject(Place.class); place.setName(item.venue.name); place.setLat(item.venue.location.lat); place.setLng(item.venue.location.lng); } realm.commitTransaction();
7. Internals • Proxy class • io.realm." + modelClassName + “RealmProxy • getters & setters without extra logic • Sample generated class
8. Queries - SQL way protected List<Place> getPlaces(LatLngBounds bounds) { SQLiteDatabase db = mSqlHelper.getReadableDatabase(); final String[] columns = new String[] {FIELD_NAME, FIELD_LAT, FIELD_LNG}; final String[] selectionArgs = new String[] {bounds.southwest.latitude, bounds.northeast.latitude, bounds.southwest.longitude, bounds.northeast.longitude}; Cursor cursor = db.query(TABLE_NAME, columns, FIELD_LAT + " > ? AND " + FIELD_LAT + " < ? AND " + FIELD_LNG + " > ? AND " + FIELD_LNG + " < ?", selectionArgs, null, null, null); try { List<Place> places = new ArrayList<Place>(); for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()) { String name = cursor.getString(cursor.getColumnIndex(FIELD_NAME)); double lat = cursor.getDouble(cursor.getColumnIndex(FIELD_LAT)); double lng = cursor.getDouble(cursor.getColumnIndex(FIELD_LNG)); Place place = new Place(); place.setName(name); place.setLat(lat); place.setLng(lng); places.add(place); } return places; } finally { if (cursor != null) { cursor.close(); } }
9. Queries - Realm way protected List<Place> getPlaces(LatLngBounds bounds) { RealmResults<Place> results = mRealm.where(Place.class) .between("lat", bounds.southwest.latitude, bounds.northeast.latitude) .between("lng", bounds.southwest.longitude, bounds.northeast.longitude) .findAll(); return results; }
10. Queries RealmQuery<Place> query = mRealm.where(Place.class) .between() .greaterThan() .lessThan() .greaterThanOrEqualTo() .lessThanOrEqualTo() .equalTo() .notEqualTo() .contains() .beginsWith() .endsWith(); RealmResults<Place> results = query.findAll(); RealmResults<Place> first = query.findFirst();
11. Relationships public class City extends RealmObject { private String name; private RealmList<Place> places; } public class Place extends RealmObject { ... }
12. Sample app
13. Summary • Great API • Some limitations • Fast (but Sqlite is fast enough in most cases) • Worth to try!
14. Resources • http://realm.io/ • http://realm.io/docs/java/0.73.0/ • https://github.com/realm/realm-java • https://github.com/realm/realm-java/wiki/Current- limitations
15. Questions?
16. Thank you!