Spring Data

Question 1

What is JPA?

Answer 1

Java persistence API

• a list of interfaces meant for the mapping/managing of relational data with java objects
• describes which Java objects to persists and how to persist them
• requires a specific implementation to be used, e.g. Hibernate
• Spring Data JPA in practice: @Entity, @Table, @Id, @GeneratedValue, @Column

Question 2

What is Spring ORM and Spring Data?

Answer 2

Spring ORM = Spring Object Relational Mapping
- it is a framework built upon Hibernate, which is then built upon by Spring Data JPA

Spring Data = family of Spring modules dealing with data persistence
- includes modules such as Spring Data JPA, Spring Data MongoDB, and Spring Data Redis

Question 3

What interfaces are available in Spring Data JPA?

Answer 3

• JpaRepository
• extends PagingAndSortingRepository
• extends CrudRepository
• extends Repository

Question 4

What is @Query used for?

Answer 4

Used to define custom behavior (i.e. SQL code) that may not be provided by Spring

@Query(“SELECT * FROM users SORT BY id ASC;”)
public List getUsersSorted();

Question 5

Describe some naming conventions for Spring Data repository methods (think CRUD operations)

Answer 5

Operations

• Retrieval: find
• Creation/Update: save
• Delete: delete

Queries

• deal with collections: All
• filter by criteria: By

Examples
- saveAll(), findByName(), deleteById()