For the latest stable version, please use Spring Data Cassandra 4.4.1!

Extensions

Kotlin extensions provide the ability to extend existing classes with additional functionality. Spring Data Kotlin APIs use these extensions to add new Kotlin-specific conveniences to existing Spring APIs.

Keep in mind that Kotlin extensions need to be imported to be used. Similar to static imports, an IDE should automatically suggest the import in most cases.

For example, Kotlin reified type parameters provide a workaround for JVM generics type erasure, and Spring Data provides some extensions to take advantage of this feature. This allows for a better Kotlin API.

To retrieve a list of SWCharacter objects in Java, you would normally write the following:

Flux<SWCharacter> characters = template.query(SWCharacter.class).inTable("star-wars").all()

With Kotlin and the Spring Data extensions, you can instead write the following:

val characters = template.query<SWCharacter>().inTable("star-wars").all()
// or (both are equivalent)
val characters : Flux<SWCharacter> = template.query().inTable("star-wars").all()

As in Java, characters in Kotlin is strongly typed, but Kotlin’s clever type inference allows for shorter syntax.

Spring Data for Apache Cassandra provides the following extensions:

  • Reified generics support for CassandraOperations (including async and reactive variants), CqlOperations (including async and reactive variants)FluentCassandraOperations, ReactiveFluentCassandraOperations, Criteria, and Query.

  • [kotlin.coroutines] extensions for ReactiveFluentCassandraOperations.