realm or: how i learned to stop worrying and love my app database

RealmHow I

Learned to Stop

Worrying and

Love my App

Database

Sergi MartínezAndroid Developer at Schibsted Spain

Android GDE@sergiandreplace

The usual stuffMy big server

My big database

My mobile app

My little databas

My nice

The internet!

My big database

My mobile app

My little databas

My nice

The internet!

This tries to mimic this

My big database

My mobile app

My little databas

My nice

The internet!

Here We only need to cache entities

The initial solutionSQLite

SQLiteSQL languageRelationshipsNon-java data typesSQL QueriesSQL stuff

Do we need these?

SQLiteSQL languageRelationshipsNon-java data typesSQL QueriesSQL stuff

Do we need these? Really?

Also...SQLDbHelperSQL QueriesContent ProvidersLoadersetc

Boilerplate

OH! Wow! So much boilerplate

Boilerplate

“Hard” to create. Excessive coupling with UI

Boilerplate

“Hard” to create. Excessive coupling with UI

Probably… more boilerplate

Let’s try something different… RealmIt stores objectsHierarchical relationships (sort of)No boilerplate (just probably mappers)Fast!Reduces dev time drastically

Adding Realm to your projectYour project build.gradlebuildscript { repositories { jcenter() } dependencies { classpath "io.realm:realm-gradle-plugin:0.89.0" }}

apply plugin: 'realm-android'

Your app build.gradle

Realm Objectspublic class Minion extends RealmObject {

private String name; private int eyes; private boolean goggles;

public String getName() { return name; } public void setName(String name) { this.name = name; }

public int getEyes() { return eyes; } public void setEyes(int eyes) { this.eyes = eyes; }

public boolean hasGoggles() { return goggles; } public void setGoggles(boolean goggles) { this.goggles = goggles; }}

Must extend RealmObject

Must extend RealmObjectNot exactly true since last thursday (#$%@!). More later...

Object members that will be storedMore on types later

Usual getters and setters

Supported data typesboolean/Booleanbyte/Byteshort/Shortint/Integerlong/Long

float/Floatdouble/DoubleStringDateByte[]

Storing an objectrealm.beginTransaction();Minion minion = realm.createObject(Minion.class);minion.setName("Bob");minion.setEyes(1);minion.setGoggles(true);realm.commitTransaction();

realm.cancelTransaction();

First, we start a transaction

Then we create an instance inside our realm

We set the values

And commit the transaction. Then, our changes are saved

Or we cancel the transaction and the new object is discarded

Storing an object - IIMinion minion = new Minion();minion.setName("Bob");minion.setEyes(1);minion.setGoggles(true);

realm.beginTransaction();realm.copyToRealm(minion);realm.commitTransaction();

Another way. We create the object outside the realm

Storing an object - IIMinion minion = new Minion();minion.setName("Bob");minion.setEyes(1);minion.setGoggles(true);

realm.beginTransaction();realm.copyToRealm(minion);realm.commitTransaction();

Then, we begin a transaction, copy the object into the realm, and commit

Obtaining your RealmFirst, create your Realm configurationRealmConfiguration config = new RealmConfiguration.Builder(context) .name("myrealm.realm") .encryptionKey(getKey()) .schemaVersion(42) .setModules(new MySchemaModule()) .migration(new MyMigration()) .build();

Obtaining your RealmThen, get an instanceRealmConfiguration config = new RealmConfiguration.Builder(context) .name("myrealm.realm") .encryptionKey(getKey()) .schemaVersion(42) .setModules(new MySchemaModule()) .migration(new MyMigration()) .build();

Realm myRealm = Realm.getInstance(config);

Obtaining your RealmOr use the default Realm InstanceRealmConfiguration config = new RealmConfiguration.Builder(context) .name("myrealm.realm") .encryptionKey(getKey()) .schemaVersion(42) .setModules(new MySchemaModule()) .migration(new MyMigration()) .build();

Realm.setDefaultConfiguration(config);

And obtain it anywhere Realm realm = Realm.getDefaultInstance(); // Stuff realm.close();

Close your RealmsFor each

Realm.getDefaultInstance()

Realm.getInstance()

you must execute realm.close() at the end

Querying a RealmRealm uses fluent syntax. Just create a RealmQuery object based on the Realm class you wantRealmQuery<Minion> query = realm.where(Minion.class);

Add operations and filters and executeRealmResults<Minion> results = query.equalTo(“name”, “Bob”).findAll();

Do something with the resultfor (Minion minion:results) {…. //Do stuff}

Query operatorsbetween()greaterThan()lessThan()greaterThanOrEqual()lessThanOrEqual()

equalTo()notEqualTo()contains()beginsWith()endsWith()

Annotations@Index

@PrimaryKey

@Ignore

@Required

Relationships - 1:NJust have a RealmObject with a RealmObjectpublic class Minion extends RealmObject { private String name; private int eyes; private boolean goggles; private Banana banana

//Getters, setters and so on

Public class Banana extends RealmObject { …}

Storing 1:N related objectsrealm.beginTransaction()

Banana banana = realm.createObject(Banana.class);banana.setSomething…

Minion minion = realm.createObject(Minion.class);minion.setName(“Bob”);minion.setBanana(banana);

realm.writeTransaction();

Relationships - M:NJust have a RealmObject with a List<? extends RealmObject>public class Minion extends RealmObject { private String name; private int eyes; private boolean goggles; private RealmList<Banana> bananas

//Getters, setters and so on

Public class Banana extends RealmObject { …}

Storing M:N related objectsrealm.beginTransaction()

Banana banana = realm.createObject(Banana.class);banana.setSomething…

Minion minion = realm.createObject(Minion.class);minion.setName(“Bob”);minion.getBananas().add(banana);

realm.writeTransaction();

Querying M:N related objectsRealmResults<Minion> minions = realm.where(Minions.class) .equalTo("banana.size", "big") .findAll();

ThreadingEach Realm should live in the same Thread is has been created

You can’t pass Realms between threads

Realms are automatically updated between threads IF they are in threads with a Looper

Otherwise… Realm.refresh()

More thingsDynamic realms

Schemas

Migrations

UI controls

Browsers

etc...

Brand new changesThis week on Realm:

RealmModel interface + static methods

RealmCollection/RealmOrderedCollection Interfaces

Primary keys can be null!

How I use itpublic abstract class VOBaseMapper<V extends RealmObject,E> {

public abstract V toVO(E entity); public abstract E toEntity(V vo) ;

public RealmList<V> toVO(List<E> entities) { RealmList<V> realmList=new RealmList<V>(); for (E entity:entities) { realmList.add(toVO(entity)); } return realmList; }

How I use it public List<E> toEntity(RealmList<V> vos) { List<E> applicationEntityList = new ArrayList<>(); for(V vo :vos){ applicationEntityList.add(toEntity(vo)); } return applicationEntityList; }

public List<E> toEntity(RealmResults<V> vos) { List<E> applicationEntityList = new ArrayList<>(); for(V vo :vos){ applicationEntityList.add(toEntity(vo)); } return applicationEntityList; }}

How I use itpublic class UserVOMapper extends VOBaseMapper<UserVO,User > {

private User user;

@Override public UserVO toVO(User user) { UserVO vo=new UserVO(); vo.setName(user.name); vo.setEmail(user.email); return vo; }

@Override public User toEntity(UserVO vo) { User user= new User(); user.name=vo.getName(); user.email=vo.getEmail(); return user; }}

And that’s not allBut enough for today.Questions?

@sergiandreplace

Thanks for coming

realm or: how i learned to stop worrying and love my app database

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