An Introduction to Spring Data

A Developer‘s View5

What to expect? NOT!7

Retrospect

Relational databases

Scaling

Data structures

Graphs

Documents

Column families

Key Value

Forest for the woods?

A Developer‘s View19

Spring Data

" … provide a familiar and consistent Spring-based programming model while not over-abstracting custom traits of the speciﬁc store.© 2011 SpringOne 2GX 2011. All rights reserved. Do not distribute without permission.

Building blocks

Spring

Mapping

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

Templates

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

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 Querydsl39

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

Wrap up• Sophisticated mapping support• Templates• Repositories• Querydsl• Spring namespace• Geospatial support• Cross-store persistence45

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 - SQLFire46

Questions?

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-redis51

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/92222752

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An Introduction to Spring Data

by Oliver Gierke on Oct 26, 2011

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