A simple ToDo app to demonstrate the use of Realm Database in android to perform some basic CRUD operations like Create, Update and Delete.

@RealmClass
open class Note() : RealmModel {
    @PrimaryKey
    var id: String = ""

    @Required
    var title: String? = ""

    @Required
    var description: String? = ""
}

fun addNote(noteTitle: String, noteDescription: String) {
        realm.executeTransaction { r: Realm ->
            val note = r.createObject(Note::class.java, UUID.randomUUID().toString())
            note.title = noteTitle
            note.description = noteDescription

            realm.insertOrUpdate(note)
        }
    }

private fun getAllNotes(): MutableLiveData<List<Note>> {
        val list = MutableLiveData<List<Note>>()
        val notes = realm.where(Note::class.java).findAll()
        list.value = notes?.subList(0, notes.size)
        return list
    }

fun updateNote(id: String, noteTitle: String, noteDesc: String) {
        val target = realm.where(Note::class.java)
            .equalTo("id", id)
            .findFirst()

        realm.executeTransaction {
            target?.title = noteTitle
            target?.description = noteDesc
            realm.insertOrUpdate(target)
        }
    }

fun deleteNote(id: String) {
        val notes = realm.where(Note::class.java)
            .equalTo("id", id)
            .findFirst()

        realm.executeTransaction {
            notes!!.deleteFromRealm()
        }
    }

fun deleteAllNotes() {
        realm.executeTransaction { r: Realm ->
            r.delete(Note::class.java)
        }
    }