Spring Data JPA · What is Spring Data JPA? ORM CRUD Query DSL Wednesday, August 21, 13. What is Spring Data JPA? ORM CRUD Query DSL Auditing Wednesday, August 21, 13. What is Spring

Spring Data JPASpring Data Commons

Dan Bunker

Wednesday, August 21, 13

Training Overview•Intro to Spring Data JPA

•JPA Repositories•Queries•Paging, Sorting and Auditing

•LDS ServiceProxy to Spring Data JPA

•Labs and Hands on Work


Prerequisites•Java 6+ and IDE Environment

•Class Provided Pet Store App

•Previous Experience with Spring and JPA

•Part 1, 2 and 3 Spring Training•Introduction to JPA Training

•Previous Oracle Experience and RDBM’s

•Understanding of Maven


What is Spring Data JPA?

ORM



ORM

CRUD



ORM

CRUD

Query DSL



ORM

CRUD

Query DSL

Auditing



ORM

CRUD

Query DSL

Auditing

Pagination



ORM

CRUD

Plug n Play - Fully Customizable

Query DSL

Auditing

Pagination


Tables


Entities@Entitypublic class Animal extends AbstractAuditingEntity {! @Id! @SequenceGenerator(name = "AnimalIdSequence", sequenceName = "ANIMAL_ID_SEQ", allocationSize=1)! @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="AnimalIdSequence")! private Long id;

@Length(max=50) @NotEmpty @Column(unique=true, nullable=false) private String name;

...}


Instead of writing this...public Animal findAnimal (Long animalId) {

return entityManager.find(Animal.class, animalId);}

public void deleteAnimal (Long animalId) { Animal a = entityManager.find(Animal.class, animalId); entityManager.remove(a);}

public Animal saveAnimal (Animal animal) { return entityManager.persist(animal);}

etc.


why not write this?public interface AnimalRepository

extends CrudRepository<Animal, Long> {

}


How We Got HereODBC/JDBC



EJB 1.x/2.x



EJB 1.x/2.x

Hibernateibatis Apache DB Utils JDO



EJB 1.x/2.x


EJB 3 / JPASpring JDBC



EJB 1.x/2.x


EJB 3 / JPASpring JDBC

Value Add on Services

Spring Batch Spring Data JPAActiveJDBC QueryDSL

?


Spring Data JPAPros Cons

•Reduces JPA code

•Replaces ServiceProxy

•Paging and Auditing

•Compatible with other Spring Data projects like JDBC, Mongo, Gemfire...


Spring Data JPAPros Cons

•Reduces JPA code

•Replaces ServiceProxy

•Paging and Auditing

•Compatible with other Spring Data projects like JDBC, Mongo, Gemfire...

•No control over DSL generated queries

•Java is a compiled language

•Still requires entity modeling and an understanding of JPA


Lab 1Explain what Spring Data JPA does?


Assignment


Assignment•Write out what you think Spring Data JPA does and how it could help or hurt a software project using Spring and JPA.

•Send me an email to [email protected] with your response.


mailto:[email protected]

mailto:[email protected]

Solution 1Explain what Spring Data JPA does?


Solution 1


Solution 1•Spring Data JPA utilizes what JPA already knows about your entity and table relationships to provide off-the-shelf CRUD operations, automatic finder queries, jpa queries and paging support. It can reduce persistence code by handling a large portion of your standard boilerplate queries using a query DSL.


Enough Theory•stack-thirdparty maven pom version 3.3.1 and higher contains Spring Data JPA

•Enable in your maven pom by adding dependency:

•groupId: org.springframework.data•artifactId: spring-data-jpa

•Add namespace and schema location to spring context.xml

•Enable <jpa:repositories /> tag


!<dependencies>

...! ! <dependency>! ! ! <groupId>org.springframework.data</groupId>! ! ! <artifactId>spring-data-jpa</artifactId>! ! </dependency>

...! </dependencies>

pom.xml


xmlns:jpa="http://www.springframework.org/schema/data/jpa"xsi:schemaLocation="http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd"

applicationContext.xml

<jpa:repositories base-package="org.lds.stack.petstore.admin.repository" />


http://www.springframework




http://www

http://www

Spring Data JPASpring Data Commons

In Depth


Services vs Repositories•When writing an application you need to decide:

•Where should my transaction boundaries live?•Where should persistence code go?•Where should actual queries live in the code?




•If you answered “view tier” for any of these questions, you’re probably a manager




•If you answered “view tier” for any of these questions, you’re probably a manager

•Most of these decisions will come down to either the service or persistence tier


Basic RundownService Tier Persistence Tier


Basic Rundown

@Service @Repository @Entity

Service Tier Persistence Tier


Basic Rundown

DashboardService




Basic Rundown

DashboardService



UserRepository

MessageRepository


Basic Rundown

DashboardService



UserRepository

MessageRepository

User

Message


Basic Rundown

DashboardService



UserRepository

MessageRepository

User

Message

Why add @Repository layer?JDBC, JPA, Mongo, etc. (Impls)


Basic Rundown

DashboardService



UserRepository

MessageRepository

User

Message


Typically Tx’s are handled here


Basic Rundown

DashboardService



UserRepository

MessageRepository

User

Message


Typically Tx’s are handled here

Dependency Flow


CrudRepositoryContract from

Spring Data Commons


CrudRepository

Extension ofSpring Repo Concept

Contract fromSpring Data Commons


CrudRepository


Domain TypeDomain ID



CrudRepository


Domain TypeDomain ID

•count()•delete(ID id)•delete(Iterable entities)•delete(T entity)•deleteAll()•exists(ID id)•findAll()•findAll(Iterable entities)•findOne(ID id)•save(Iterable entities)•save(S entity)



PagingAndSortingRepositContract from

Spring Data Commons



Spring Data Commons

PageRequest



Spring Data Commons

PageRequest

Page



Spring Data Commons

PageRequest

Page

Extends CrudRepository

•findAll(Pageable request)•findAll(Sort sort)


JpaRepository

Impl ofSpring Data Commons


JpaRepository


JPA BasedImplementation


JpaRepository



ProcessesQuery DSL Statements


JpaRepository



•findAll()•findAll(Sort sort)•flush()•save(Iterable entities)•saveAndFlush(T entity)



JpaRepository



•findAll()•findAll(Sort sort)•flush()•save(Iterable entities)•saveAndFlush(T entity)

All features from•CrudRepository•PagingAndSortingRepository



•DSL = Domain Specific Language

•Spring Data JPA DSL are query mappings based off of your Repository contract method names

•findByName(...);•findByNameAndDescription(...);

•The DSL consists of keywords mixed with the column attribute names of the domain

•Queries become more “English’y”

DSL Queries


DSL KeywordsAnd findByCityAndState where x.city = ? and x.state = ?

Or findByCityOrZip where x.city = ? or x.zip = ?

Between findByCreateDateBetween where x.createDate between ? and ?

LessThan, GreaterThan findBySalaryLessThan where x.salary < ?

True, False findByMemberTrue where x.member = true

After, Before findByStartDateAfter where x.startDate > ?

Containing, StartingWith, EndingWith

findByNameContaining where x.name like ‘%?%’

IsNull, IsNotNull findByNameIsNull where x.name is null

Like, NotLike findByNameLike where x.name like ?

In, NotIn findById(Collection ids) where x.id in ?

OrderBy findByNameOrderByAgeDesc where x.name = ? order by x.age desc


Lab 2Writing DSL Queries


Assignment


Assignment•Create the following queries:

•Find animals that matches text anywhere in the name

•Find animals in a price range

•Find animals by name or description

•Hint: DSL methods go in AnimalRepository


Solution 2Writing DSL Queries


Other Query Resolutionorm.xml defined queries

<named-query name="User.findByLastname"> <query>select u from User u where u.lastname = ?1</query></named-query>




@NamedQuery defined queries@Entity@NamedQuery(name = "User.findByLastname", query = "select u from User u where u.lastname = ?1")




@NamedQuery defined queries@Entity@NamedQuery(name = "User.findByLastname", query = "select u from User u where u.lastname = ?1")

Spring Data JPA resolves to a matching method namepublic interface UserRepository extends JpaRepository<User, Long> { List<User> findByLastname(String lastname);}


@Query AnnotationUse @Query to immediately markup your contract methods

public interface UserRepository extends JpaRepository<User, Long> { @Query("select u from User u where u.firstname like %?1") List<User> findByFirstnameEndsWith(String firstname);}


@Query AnnotationUse @Query to immediately markup your contract methods

public interface UserRepository extends JpaRepository<User, Long> { @Query("select u from User u where u.firstname like %?1") List<User> findByFirstnameEndsWith(String firstname);}

Spring Data JPA handles % characters in like clauses


Native Queries with @Query can run native queries and map back into objects

public interface UserRepository extends JpaRepository<User, Long> {@Query(value = "SELECT FROM USERS WHERE EMAIL_ADDRESS = ?0", nativeQuery = true)

User findByEmailAddress(String emailAddress);}


Native Queries with @Query can run native queries and map back into objects

public interface UserRepository extends JpaRepository<User, Long> {@Query(value = "SELECT FROM USERS WHERE EMAIL_ADDRESS = ?0", nativeQuery = true)

User findByEmailAddress(String emailAddress);}

Pagination and Dynamic Sorting are not supported when using native queries


•Method names match Named Queries (xml or annotation)

•Methods annotated with @Query

•Methods parsed with Query DSL and jpaql generated

•Methods are a pass through to custom impl

Query Discovery Order


Lab 3Add an @Query Method


Assignment


Assignment•Create an @Query:

•Find all animals in a particular classification name

•Hint: The Classification model is a @ManyToOne on the Animal model.


Solution 3Add an @Query Method


PaginationUse Pageable to get auto-paging on your queries

public interface UserRepository extends JpaRepository<User, Long> { List<User> findByFirstnameContaining(String firstname, Pageable pager);}




PageableArgumentResolver




PageableArgumentResolver new PageRequest(...)


SortingUse OrderBy to make your queries ordered

public interface UserRepository extends JpaRepository<User, Long> { List<User> findByFirstnameContainingOrderById(String firstname);}




DSL OrderBy




DSL OrderBy Sort Object


Combining Sorting and

new PageRequest(int page, int size, Sort sort)




Best approach for DSL Queries




Best approach for DSL Queries

Advanced Paging, Sorting and Filtering may need to be hand rolled still or use Criteria Queries


Lab 4Add a Pageable Query


Assignment


Assignment•Update any existing DSL Query to be Pageable

•Hint: Add Pageable as a parameter in your repository. In your test construct a new PageRequest


Solution 4Add a Pageable Query


Replacing LDS ServiceProxy with JPA Repositories

Guide


ServiceProxy to

AnimalProxy

Service

@Service @Repository


ControllerCode

Presentation Tier


ServiceProxy to

AnimalProxy

Service



AnimalRepository

ControllerCode

Presentation Tier


ServiceProxy to

AnimalProxy

Service



AnimalRepository

ControllerCode

Presentation Tier


ServiceProxy to

AnimalProxy

Service



AnimalRepository

ControllerCode

Presentation Tier


ServiceProxy to

AnimalProxy

Service



AnimalRepository

ControllerCode

Presentation Tier


ServiceProxy to

AnimalProxy

Service



AnimalRepository

ControllerCode

AnimalService

Presentation Tier


ServiceProxy to

AnimalProxy

Service



AnimalRepository

ControllerCode

AnimalService

Presentation Tier


•Replace Service Proxies with JPA Repositories

•Remove Service Proxy Maven dependency

•Remove Service Proxy *context.xml markup

ServiceProxy Clean Up


Unsupported OptionsJPA Repositories don’t support embeddable logic tags

$if $endif


Unsupported OptionsJPA Repositories don’t support embeddable logic tags

$if $endif

Replace with appropriate logic in a plain service class and call needed JPA queries on the repository


•Keep method names (contracts) the same when moving to repositories from proxies

•@Find(Query) can be converted to @Query with the exception of $if endif$ statements

•Convert the ServiceProxy to a plain Spring service and have it rely on JPA Repositories. This keeps most client code unaware of any kind of change.

Migration Tips



Spring Data JPA · What is Spring Data JPA? ORM CRUD Query DSL Wednesday, August 21, 13. What is Spring Data JPA? ORM CRUD Query DSL Auditing Wednesday, August 21, 13. What is Spring

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