Spring Data Repositories

How

• Using annotated entity, we create an interface:

@Entity
public class Author {
  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  private Long id;

  private String firstName;
  private String lastName;
  @ManyToMany(mappedBy = "authors")
  private Set<Book> books;

  public Author() {
  }

  public Author(String firstName, String lastName, Set<Book> books) {...}

  // Omitted setters/getter/equals/hashcode/toString
}

public interface AuthorRepository extends CrudRepository<Author, Long>{}

• This CrudRepository interface provides several CRUD operations, and Spring will provide the implementation for us to use.

• Initialiasing with data

  • Use of CommandLineRunner which has a runnable

    • Spring will find any of these impementations and run them

    • Can be used as a main method

  • Can inject repository created, and use crud methods to add data or get data etc