Helenus

Fast and easy, functional style cutting edge Java 8 Cassandra client for C* 3.x

Features

Leverages Java 8 language capabilities to build CQL queries
Simple function-style stream API
Reactive asynchronous and synchronous API
Provides Java mapping for Tables, Tuples, UDTs (User Defined Type), Collections, UDT Collections, Tuple Collections
Uses lazy mapping in all cases where possible
Supports Java 8 Futures and Guava ListenableFuture

Requirements

JVM 8
Datastax Driver 3.x
Cassandra 3.x
Maven

Maven

Latest release dependency:

<dependencies>
	<dependency>
		<groupId>net.helenus</groupId>
		<artifactId>helenus-core</artifactId>
		<version>1.1.0_2.11</version>
	</dependency>
</dependencies>

Simple Example

Model definition:

@Table
public interface Timeline {

	@PartitionKey
	UUID userId();

	@ClusteringColumn
	@Types.Timeuuid
	Date timestamp();

	@Column
	String text();

}

Session initialization:

HelenusSession session = Helenus.init(getSession()).showCql().add(Timeline.class).autoCreateDrop().get();
Timeline timeline = Helenus.dsl(Timeline.class, session.getMetadata());

Select example:

session.select(timeline::userId, timeline::timestamp, timeline::text)
  .where(timeline::userId, eq(userId))
  .orderBy(Query.desc(timeline::timestamp)).limit(5).sync()
  .forEach(System.out::println);

Insert example:

TimelineImpl post = new TimelineImpl();
post.userId=userId;
post.timestamp=new Date(postTime+1000L*i);
post.text="hello";
session.upsert(post).sync();

Model and Repository Example

Account model:

@Table
public interface Account {
	@PartitionKey
	String accountId();
	Date createdAt();
	String organization();
	String team();
	String timezone();
	Map<String, AccountUser> users();
}

AccountUser model:

@UDT
public interface AccountUser {
	String email();
	String firstName();
	String lastName();
}

Abstract repository:

public interface AbstractRepository {
	HelenusSession session();
}

Account repository:


public interface AccountRepository extends AbstractRepository {

	static final Account account = Helenus.dsl(Account.class);
	static final String DEFAULT_TIMEZONE = "America/Los_Angeles";
	default Future<Optional<Account>> findAccount(String accountId) {

		return session()
				.select(Account.class)
				.where(account::accountId, eq(accountId))
				.single()
				.future();
	}

	default Future<Fun.Tuple2<ResultSet, String>> createAccount(
			String email,
			AccountUser user,
			String organization,
			String team,
			String timezone) {

		String accountId = AccountId.next();

		if (timezone == null || timezone.isEmpty()) {
			timezone = DEFAULT_TIMEZONE;
		}

		return session()
			.insert()
			.value(account::accountId, accountId)
			.value(account::createdAt, new Date())
			.value(account::organization, organization)
			.value(account::team, team)
			.value(account::timezone, timezone)
			.value(account::users, ImmutableMap.of(email, user))
			.future(accountId);

	}

	default Future<ResultSet> putAccountUser(String accountId, String email, AccountUser user) {

		return session()
				.update()
				.put(account::users, email.toLowerCase(), user)
				.where(account::accountId, eq(accountId))
				.future();

	}

	default Future<ResultSet> removeAccountUser(String accountId, String email) {

		return session()
				.update()
				.put(account::users, email.toLowerCase(), null)
				.where(account::accountId, eq(accountId))
				.future();

	}

	default Future<ResultSet> dropAccount(String accountId) {

		return session()
				.delete()
				.where(account::accountId, eq(accountId))
				.future();

	}

}

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