Kotlin extensions to simplify Realm API.

Description

Simplify your code to its minimum expression with this set of Kotlin extensions for Realm. Forget all boilerplate related with Realm API and perform database operations in one line of code with this lightweight library. Full test coverage.

Download for Kotlin 1.1.x and Realm 3.5.0

Grab via Gradle:

repositories {
    mavenCentral()
}

compile "com.github.vicpinm:krealmextensions:1.1.5"

//For Observable queries:
compile 'com.github.vicpinm:krealmextensions-rxjava:1.1.5'

//For Single and Flowable queries:
compile 'com.github.vicpinm:krealmextensions-rxjava2:1.1.5'

Download for Kotlin 1.1.x and Realm 3.1.3

Grab via Gradle:

repositories {
    mavenCentral()
}

compile 'com.github.vicpinm:krealmextensions:1.0.9'

Download for Kotlin 1.0.x and Realm 2.2.1

Grab via Gradle:

repositories {
    mavenCentral()
}

compile 'com.github.vicpinm:krealmextensions:1.0.6'

Features

Forget about:

• Realm instances management
• Transactions
• Threads limitations
• Boilerplate related with Realm API

Usage

Store entities

All your entities should extend RealmObject.

Before (java)

User user = new User("John");

Realm realm = Realm.getDefaultInstance();
try{
   realm.executeTransaction(realm -> {
      realm.copyToRealmOrUpdate(user);  
   });  
} finally {
   realm.close();
}

After (Kotlin + extensions)

User("John").save()

Save method creates or updates your entity into database. You can also use create() method, which only create a new entity into database. If a previous one exists with the same primary key, it will throw an exception.

Save list: Before (java)

List<User> users = new ArrayList<User>(...);

Realm realm = Realm.getDefaultInstance();
try {
    realm.executeTransaction(realm -> {
        realm.copyToRealmOrUpdate(users);  
    });
} finally {
    realm.close();
}

Save list: After (Kotlin + extensions)

listOf<User>(...).saveAll()

If you need to provide your own Realm instance, you can use the saveManaged(Realm) and saveAllManaged(Realm) methods. These methods return managed objects. You should close manually your Realm instance when you finish with them.

Query entities

All query extensions return detached realm objects, using copyFromRealm() method.

Get first entity: Before (java)

Realm realm = Realm.getDefaultInstance();
try {
   Event firstEvent = realm.where(Event.class).findFirst();
   firstEvent = realm.copyFromRealm(event);
} finally {
   realm.close();
}

Get first entity: After (Kotlin + extensions)

val firstEvent = Event().queryFirst()

You can use lastItem extension too.

Get all entities: Before (java)

Realm realm = Realm.getDefaultInstance();
try {
    List<Event> events = realm.where(Event.class).findAll();
    events = realm.copyFromRealm(event);
} finally {
    realm.close();
}

Get all entities: After (Kotlin + extensions)

val events = Event().queryAll()

Get entities with conditions: Before (java)

Realm realm = Realm.getDefaultInstance();
try{
    List<Event> events = realm.where(Event.class).equalTo("id",1).findAll();
    events = realm.copyFromRealm(event);
} finally {
    realm.close();
}

Get entities with conditions: After (Kotlin + extensions)

val events = Event().query { query -> query.equalTo("id",1) }

If you only need the first or last result, you can also use:

val first = Event().queryFirst { query -> query.equalTo("id",1) }
val last = Event().queryLast { query -> query.equalTo("id",1) }

Get sorted entities

val sortedEvents = Event().querySorted("name",Sort.DESCENDING) 

val sortedEvents = Event().querySorted("name",Sort.DESCENDING) { query -> query.equalTo("id",1) }

Delete entities

Delete all: Before (java)

Realm realm = Realm.getDefaultInstance();
try{
    List<Event> events = realm.where(Event.class).findAll();
    realm.executeTransaction(realm -> {
        events.deleteAllFromRealm();
    });
} finally {
    realm.close();
}

Delete all: After (Kotlin + extensions)

Event().deleteAll()

Delete with condition: Before (java)

Realm realm = Realm.getDefaultInstance();
try{
    List<Event> events = realm.where(Event.class).equalTo("id",1).findAll().deleteAllFromRealm();
    events = realm.copyFromRealm(event);
} finally {
    realm.close();
}

Delete with condition: After (Kotlin + extensions)

Event().delete { query -> query.equalTo("id", 1) }

Observe data changes

Before (java)

Realm realm = Realm.getDefaultInstance();
Observable<List<Event>> obs =  realm.where(Event.class).findAllAsync()
.asObservable()
.filter(RealmResults::isLoaded)
.map(realm::copyFromRealm)
.doOnUnsubscribe(() -> realm.close());

After (Kotlin + extensions)

val obs = Event().queryAllAsObservable()

Observe query with condition: Before (java)

Realm realm = Realm.getDefaultInstance();
Observable<List<Event>> obs =  realm.where(Event.class).equalTo("id",1).findAllAsync()
.asObservable()
.filter(RealmResults::isLoaded)
.map(realm::copyFromRealm)
.doOnUnsubscribe(() -> realm.close());

Observe query with condition: After (Kotlin + extensions)

val obs = Event().queryAsObservable { query -> query.equalTo("id",1) }

These kind of observable queries have to be performed on a thread with a looper attached to it. If you perform an observable query on the main thread, it will run on this thread. If you perform the query on a background thread, a new thread with a looper attached will be created for you to perform the query. This thread will be listen for data changes and it will terminate when you call unsubscribe() on your subscription.

RxJava 2 Support (thanks to @SergiyKorotun)

val flow = Event().queryAllAsFlowable()
val flow = Event().queryAsFlowable { query -> query.equalTo("id", 1) }

val single = Event().queryAllAsSingle()
val single = Event().queryAsSingle { query -> query.equalTo("id", 1) }

Proguard

You need to add these rules if you use proguard, for rxjava and realm:

# rxjava
-dontwarn sun.misc.**

-keepclassmembers class rx.internal.util.unsafe.*ArrayQueue*Field* {
   long producerIndex;
   long consumerIndex;
}

-keepclassmembers class rx.internal.util.unsafe.BaseLinkedQueueProducerNodeRef {
    rx.internal.util.atomic.LinkedQueueNode producerNode;
}

-keepclassmembers class rx.internal.util.unsafe.BaseLinkedQueueConsumerNodeRef {
    rx.internal.util.atomic.LinkedQueueNode consumerNode;
}

-dontnote rx.internal.util.PlatformDependent

-keepnames public class * extends io.realm.RealmObject
-keep class io.realm.annotations.RealmModule
-keep @io.realm.annotations.RealmModule class *
-keep class io.realm.internal.Keep
-keep @io.realm.internal.Keep class *
-dontwarn io.realm.**