Spring Data JPA

What is Spring Data JPA?

Spring Data JPA is an abstraction over JPA, making it easier to work with database operations by providing a framework for handling CRUD (Create, Read, Update, Delete) operations without writing much code. It automates database interactions, saving you from writing boilerplate code.

How Does Spring Data JPA Work?

Spring Data JPA uses the concept of repositories to manage database access. The framework provides a set of predefined interfaces like CrudRepository and JpaRepository that come with built-in methods for handling common tasks like saving, deleting, and finding data.

Setting Up Spring Data JPA

To use Spring Data JPA, you need to:

• Add the necessary dependencies (usually spring-boot-starter-data-jpa and ojdbc).
• Configure your database connection in application.properties or application.yml with spring.datasource settings. Click here for JPA Config
• Annotate your classes with JPA annotations like @Entity, @Id, @Table, and so on, to define them as entities in the database.

Key Concepts of Spring Data JPA

Entity Classes: These are the classes mapped to tables in the database. Each class represents a table, and each instance of the class represents a row in the table. For example:

Repository Interfaces: Spring Data JPA lets you create repository interfaces for your entities. By extending JpaRepository or CrudRepository, you get a bunch of ready-made database operations:

Here, JpaRepository<Programmer, Integer> allows you to perform CRUD operations for User entities with a primary key of type Integer.

Annotations:

• @Entity: Specifies that the class is an entity to be mapped to a database table.
• @Id: Marks the primary key of the entity.
• @GeneratedValue: Configures how the primary key is generated.
• @Column: Configures specific columns in the table if needed (optional).

Saving Data

Now, in the Controller or Service layer, we will inject the ProgrammerRepo interface and create a reference of the interface. Then just use the save method.