我有两个例子，当从不同的上下文调用时，子实体save的工作方式不同。当我在没有级联父级的情况下更新子级时，修改后的数据也会被更新，但这只发生在从控制器调用时 CommandLineRunner 父级更新不会发生。
这是我的服务

@Service
public class BookService {

    private final BookAuthorRepository bookAuthorRepository;

    private final BookRepository bookRepository;

    @Autowired
    public BookService(BookAuthorRepository bookAuthorRepository, BookRepository bookRepository) {
        this.bookAuthorRepository = bookAuthorRepository;
        this.bookRepository = bookRepository;

    }

    public void updateBookAuth() {
        Book book = bookRepository.findById(3).get();
        book.setName("should not update");
        book.getBookAuthor().setName("new name");
        bookAuthorRepository.save(book.getBookAuthor());
    }
}

当我从下面的类调用它时，只有 BookAuthor 名称被更新，这是正确的行为。

@Component
public class MyRunner implements CommandLineRunner {

    @Autowired
    private BookService bookService;

    @Override
    public void run(String... args) throws Exception {
         bookService.updateBookAuth();
    }
}

但如果我从控制器调用此服务方法：

@RestController
public class BookController {

    private final BookService bookService;

    public BookController(BookService bookService) {
        this.bookService = bookService;
    }

    @GetMapping("/")
    public void test() {
        bookService.updateBookAuth();
    }
}

然后两者 Book 姓名和 BookAuthor 名字更新了，但我不明白为什么 Book 名称已更新。
以下是实体：

@Entity
public class Book {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    private String name;
    @OneToOne
    private BookAuthor bookAuthor;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getId() {
        return id;
    }

    public BookAuthor getBookAuthor() {
        return bookAuthor;
    }

    public void setBookAuthor(BookAuthor bookAuthor) {
        this.bookAuthor = bookAuthor;
    }
}

@Entity
public class BookAuthor {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    private String name;
    @OneToOne(mappedBy = "bookAuthor")
    private Book book;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public Integer getId() {
        return id;
    }

    public Book getBook() {
        return book;
    }

    public void setBook(Book book) {
        this.book = book;
    }
}

我还考虑了事务性，如果我在方法上写事务，那么所有上下文都会打开，父-子上下文都会更新，但在这种情况下，我不使用它，为什么会发生这种情况？