namila007

@Override
	public Book add( Book o )
	{
		//if author n publisher gets an id we can search the db and assign them
		if ( o.getAuthor().getId() != 0 )
		{
			Author author = checkIfIdIsPresentandReturnAuthor( o.getAuthor().getId() );
			o.setAuthor( author );
			author.addBook( o );
		}

namila007

@Validated
@RestController
@RequestMapping("/api/v1/author")
public class AuthorController
{

	@Autowired
	private AuthorService authorMainService;

	@GetMapping(value = "/{id}")

namila007

@Data
public class Resultset<T>
{
	private HttpStatus status;
	@JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "dd-MM-yyyy hh:mm:ss")
	private LocalDateTime timestamp;
	private T data;

	private Resultset()
	{

namila007

@SuppressWarnings( "unchecked" )
public class ResponseWrapper<T> extends ResponseEntity<T>
{
	public ResponseWrapper(T t , HttpStatus status ){
		super( ( T ) new Resultset<>( t,status ),status);
	}
}

namila007

public interface MainService <T>
{
	 Page<T> getAll( Pageable pageable);
	 T add( T o);
	 T update (T o, int id);
	 T getById( int id );
	 T deleteById(int id);
}

namila007

@SuppressWarnings("unchecked")
@Service
@NoArgsConstructor
public class AuthorServiceImp extends AuthorService
{

	@Autowired
	private AuthorRepository authorRepository;

	@Override

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@Repository
public interface AuthorRepository extends JpaRepository<Author,Integer>
{
}

namila007

@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table(name = "publisher")
public class Publisher implements Serializable
{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

namila007

@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@Table(name = "book")
public class Book implements Serializable
{
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

namila007

@SpringBootApplication
public class RestSpringTestApplication {

	public static void main(String[] args) {
		SpringApplication.run(RestSpringTestApplication.class, args);
	}

}