LiveRealmData.kt

gistfile1.txt

/**
 * Class connecting the Realm lifecycle to that of LiveData objects.
 * Realm will remain open for as long as any LiveData objects are being observed.
 */
abstract class LiveRealmData<T: RealmModel>(val config: RealmConfiguration) : LiveData<RealmResults<T>>() {

    private val listener = RealmChangeListener<RealmResults<T>> { results -> value = results }
    private lateinit var realm: Realm
    private var results: RealmResults<T>? = null

    override final fun onActive() {
        realm = Realm.getInstance(config)
        results = runQuery(realm);
        results.addChangeListener(listener)
        value = results;
    }
    override final fun onInactive() {
        results!!.removeAllChangeListeners()
        results = null
        realm.close()
    }

    abstract fun runQuery(realm: Realm): RealmResults<T>
}

fun usage() : LiveData<RealmResults<Person>> {
    return object: LiveRealmData<Person>(getConfig())  {
        override fun runQuery(realm: Realm): RealmResults<Person> {
            // Called on UI thread
            return realm.where(Person::class.java).findAllAsync()
        }
    }
}