© 2012 SpringSource, by VMware

Hands On Spring Data

Eric Bottard, Developer Advocate, VMware@ebottardFlorent Biville, Developer, Lateral Thoughts@fbiville

Eric BOTTARD

• Developer Advocate VMware• @ebottard• ebottard@vmware.com

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Florent BIVILLE

• Développeur chez LateralThoughts• @fbiville

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Spring Data is an umbrella project which aims to provide a familiar and consistent Spring-based programming model for for new datastores while retaining store-specific features and capabilities

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Relational

JDBCJPA

Document store

MongoDBCouchDB

Column oriented

HBaseCassandra

Graph

Neo4jOrientDB

Data Grids

GemFireCoherenceTerracotta

Key Value

RedisRiak

Big Data

Hadoop

Templates

Mapping

Mapping

• Tells the framework how to store object properties and relationships

• Favors convention over configuration• Does not try to shoehorn one model into another (e.g.

does not use JPA annotations for Mongo)

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Example: MongoDB@Document@CompoundIndexes({ @CompoundIndex(name = "age_idx", def = "{'lastName': 1, 'age': -1}")})public class Person<T extends Address> {

@Id private String id;

@Indexed(unique = true) private Integer ssn;

@Field("fName") private String firstName;

@Indexed private String lastName;

@Transient private Integer accountTotal;

@DBRef private List<Account> accounts;

private T address;

Repositories

Repositories

public interface PersonRepository extends CrudRepository<User, Long> { …

}

No implementation needed!

Magic Finders

Magic Finderspublic interface PersonRepository extends Repository<User, Long> {

List<Person> findByEmailAddressAndLastname(EmailAddress emailAddress, String lastname);

// Enables the distinct flag for the query List<Person> findDistinctPeopleByLastnameOrFirstname(String lastname, String firstname); List<Person> findPeopleDistinctByLastnameOrFirstname(String lastname, String firstname);

// Enabling ignoring case for an individual property List<Person> findByLastnameIgnoreCase(String lastname); // Enabling ignoring case for all suitable properties List<Person> findByLastnameAndFirstnameAllIgnoreCase(String lastname, String firstname);

// Enabling static ORDER BY for a query List<Person> findByLastnameOrderByFirstnameAsc(String lastname); List<Person> findByLastnameOrderByFirstnameDesc(String lastname);}

Pagination

Pagination and Dynamic Ordering

public interface PersonRepository extends CrudRepository<User, Long> { Page<User> findByLastname(String lastname, Pageable pageable);

List<User> findByLastname(String lastname, Sort sort);

// NOTE: Pageable embeds a Sort

}

Queries

Explicit Queries

public interface ProductsRepository extends JpaRepository<Product, Long> {

@Query(value = "select p from Product p order by p.rating desc", countQuery = "select count(p) from Product p") Page<Product> findTopRated(Pageable pageable);}

Cross Store support

Query DSL Integration

REST

REST Shell

Customization

JSON

Mongo DB - schema-less document DB

databasesmongo> show dbs;

myDatabase 0.3046578 GBmongo> use myDatabase;

collectionsmongo> show collections;

rockCollectioncolleagueSean

mongo> db.rockCollection.find().pretty(); // last call “prettifies” output

documentsmongo> db.rockCollection.find({name:"The Beatles"}).pretty();

{"_id" : ObjectId("50b7d870744e5ef5eee5224e"),"_class" : "xxx.music.domain.Band","name" : "The Beatles",[...] }

MongoDB: Queries as JSON documents

db.inventory.find({ price:1.99, $or: [ { qty: { $lt: 20 } }, { sale: true } ] })

GridFS - can I haz large objectz?• mongo> show collections;

– fs.chunks– fs.files

• CHUNKS– 256KB portion of a Mongo object (a.k.a. file), stored into

collection “fs.chunks”• FILES

– Metadata about the file stored into “fs.files”: filename, content type ...

• Spring Data brings– GridFsTemplate– GridFsResource (wraps GridFSDBFile)

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Nodes & Relationships

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NoSQLstandsFor: "Not Only

SQL"SpringData

HELPS_WITHhow: "it roxx"

Spring

IS_PART_OF

Nodes

Properties

Relationship

Cypher

Neo4J - Cypher Query Language

start doctor=node:characters(character = 'Doctor') match (doctor)<-[:COMPANION_OF]-(companion) -[:APPEARED_IN]->(episode) return companion.character, count(episode) order by count(episode) desc limit 5

Image credits

• keys http://www.sxc.hu/photo/1381979• spiderweb http://www.sxc.hu/photo/1309629• columns http://www.sxc.hu/photo/511217• documents http://www.sxc.hu/photo/913588• umbrella http://www.sxc.hu/photo/1182110• nail http://www.sxc.hu/photo/1101239• relational http://www.sxc.hu/photo/541351• callback http://www.sxc.hu/photo/1134440• repositories http://www.sxc.hu/photo/1352633• pagination http://www.sxc.hu/photo/830250• magic http://www.sxc.hu/photo/829135• cypher http://www.sxc.hu/photo/1118342• mapping http://www.sxc.hu/photo/1147986• grid http://www.sxc.hu/photo/1222068• elephant http://www.sxc.hu/photo/1168187• cross knot http://www.sxc.hu/photo/1396427• rope knot http://www.sxc.hu/photo/1181983• married http://www.sxc.hu/photo/937988• shell http://www.sxc.hu/photo/866402• diesel http://www.sxc.hu/photo/1076436• car tuning http://www.sxc.hu/photo/5877• rest on couch: If you haven’t, go watch Fight Club. NOW.

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