Spring Data JPA

External

• https://spring.io/projects/spring-data-jpa

Internal

• Spring Data
• JPA

Overview

Spring Data JPA is a Spring Data project that assists with implementing JPA-based repositories, which persist data in relational databases. The approach involves writing the repository interface, including custom finder methods, and Spring will provide the implementation automatically.

Spring Persistence Concepts

Spring Persistence Concepts

Spring Boot Support

To add support for Spring Data JPA to a Spring Boot project, add the following starter dependency:

dependencies {
    implementation('org.springframework.boot:spring-boot-starter-data-jpa')
}

This starter dependency also transitively includes Hibernate as the JPA implementation.

Spring Data JPA needs a database to work with. This is how to add H2 support:

dependencies {
    runtimeOnly('com.h2database:h2')
}

Adding Persistence to an Application with Spring Data JPA

Annotate Domain Objects with @Entity

Annotate your domain objects that require persistence with @Entity and designate their primary key field with @Id and optionally with @GeneratedValue. JPA requires each entity class to expose a no-argument constructor, which can be coded manually, or it can be generated with Lombok's @NoArgConstructor:

@NoArgConstructor(access=AccessLevel.PRIVATE, force=true)

Spring Data JPA Repository

This is a Spring Data JPA concrete repository implementation that conceals from the application low-level data access details while exposing a domain model-typed API, represented by the example "IngredientRepository" interface.

TODO

TODO

• How to tell that a JPA repository should use a specific database. How is that configured?
• @EnableJpaRepositories(basePackages = "com.example.dev.myproject.driver.repo")