An Introduction to Spring Data

An Introduction to Spring Data

Oliver Gierke - SpringSource, a division of VMware

© 2011 SpringOne 2GX 2011. All rights reserved. Do not distribute without permission.

Oliver Gierke

Spring Data
Core/JPA/MongoDB

ogierke@vmware.com
www.olivergierke.de
olivergierke

2 © 2011 SpringOne 2GX 2011. All rights reserved. Do not distribute without permission.

What to expect?


Why?


How?

Why?


How?

Why?

What?


What to expect?
NOT!


Hibari Voldemort
Membase
Riak Cassandra
Redis
SimpleDB (No)SQL MongoDB

OrientDB CouchDB
HBase
Sones
Neo4J

There‘s some
Spring for that!


" … provide a familiar and
consistent Spring-based
programming model while
not over-abstracting custom
traits of the speciﬁc store.


JDBC JPA


Entity mapping

@Document
class Person {

@Id private BigInteger id;
@Indexed private String firstname, lastname;
@Field(„email“) private String emailAddress;
@DBRef private Set<Person> colleagues;

public Person(String firstname) { … }

@PersistenceConstructor
public Person(String firstname, String lastname) { … }

…
}

32

MongoOperations / -Template

public interface MongoOperations {

// Generic callback-accepting methods
<T> T execute(DbCallback<T> action);
<T> T execute(Class<?> entityClass, CollectionCallback<T> action);
<T> T execute(String collectionName, CollectionCallback<T> action);

// Higher level access methods
<T> List<T> ﬁnd(Query query, Class<T> entityClass);
void save(Object objectToSave, String collectionName);
WriteResult updateFirst(Query query, Update update, Class<?>
entityClass);

// Geo API
<T> GeoResults<T> geoNear(NearQuery near, Class<T> entityClass);
}

34

MongoTemplate usage

// Setup infrastructure
Mongo mongo = new Mongo();
MongoDbFactory factory = new SimpleMongoDbFactory(mongo, „foo“);
MongoTemplate template = new MongoTemplate(factory);

// Create and save entity
Person dave = new Person(„Dave“, „Matthews“);
dave.setEmailAddress(„dave@dmband.com“);
template.save(person);

// Query entity
Query query = new Query(new Criteria(„emailAddress“)
.is(„dave@dmband.com“));
assertThat(template.ﬁnd(query), is(dave));

35

Repositories

public interface PersonRepository extends Repository<Person, BigInteger>
{
// Finder for a single entity
Person findByEmailAddress(String emailAddress);

// Finder for multiple entities
List<Person> findByLastnameLike(String lastname);

// Finder with pagination
Page<Person> findByFirstnameLike(String firstname, Pageable page);

// Geospatial queries
List<Person> findByLocationNear(Point location, Distance distance);
GeoResults<Person> findByLocationNear(Point location);
}

37

Repositories usage

<mongo:repositories base-package=„com.acme.repositories“ />

@Component
public class MyClient {

@Autowired
private PersonRepository repository;

public List<Person> doSomething() {

Point point = new Point(43.7, 48.8);
Distance distance = new Distance(200, Metrics.KILOMETERS);
return repository.ﬁndByLocationNear(point, distance);
}
}

38

Repositories
Querydsl

39

MongoTemplate usage

public interface QueryDslPredicateExecutor<T> {
T findOne(Predicate predicate);
List<T> findAll(Predicate predicate);
}

public interface PersonRepository extends Repository<Person, ObjectId>,
QueryDslPredicateExecutor { … }

QPerson $ = QPerson.person;
BooleanExpression left = $.lastname.contains(„eth“);
BooleanExpression right = $.firstname.is(„Carter“);

List<Person> result = repository.findAll(left.or(right));
assertThat(result.size(), is(2));
assertThat(result, hasItems(dave, carter));

40

JPA entity mapping

@Entity
class Person {

@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private BigInteger id;
private String ﬁrstname, lastname;

@Column(name=„email“)
private String emailAddress;

@OneToMany
private Set<Person> colleagues;
}

42

Repository

public interface PersonRepository extends Repository<Person, BigInteger>
{
// Finder for a single entity
Person findByEmailAddress(String emailAddress);

// Finder for multiple entities
List<Person> findByLastnameLike(String lastname);

// Finder with pagination
Page<Person> findByFirstnameLike(String firstname, Pageable page);
}

<jpa:repositories base-package=„com.acme.repositories“ />

43

Wrap up

• Sophisticated mapping support
• Templates
• Repositories
• Querydsl
• Spring namespace
• Geospatial support
• Cross-store persistence

45

Upcoming Talks

• Today
– 10:15 - Spring Data Gemﬁre
– 12:45 - Spring Data MongoDB & CloudFoundry
– 4:30 - Spring Data Neo4J

• Thursday
– 8:30 - Spring Data JPA & Repositories
– 10:15 - Polyglot persistence

• Friday
– 8:30 - SQLFire

46

Play with it


Participate


Spread the word


Resources

• www.springframework.org/spring-data
• github.com/SpringSource/spring-data-mongodb
• http://www.se-radio.net/2010/07/episode-165-nosql-
and-mongodb-with-dwight-merriman
• http://kkovacs.eu/cassandra-vs-mongodb-vs-
couchdb-vs-redis

51

Sources
• Building blocks - http://www.sxc.hu/photo/297189
• Columns - http://www.sxc.hu/photo/1033540
• Dilemma - http://www.sxc.hu/photo/125069
• Forest - http://www.sxc.hu/photo/1274066
• Glasses - http://www.sxc.hu/photo/696003
• Mapping - http://www.sxc.hu/photo/1253374
• Nails - http://www.sxc.hu/photo/933587
• Questions - http://www.sxc.hu/photo/860327
• Repository - http://www.sxc.hu/photo/1042408
• Retrospect - http://www.sxc.hu/photo/921297
• Spreadsheet - http://www.sxc.hu/photo/338505
• Spring - http://www.sxc.hu/photo/1291358
• Umbrella - http://www.sxc.hu/photo/1364634
• Template - http://www.sxc.hu/photo/619819
• Wrap up - http://www.sxc.hu/photo/922227

52

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