java - 在执行 POST 请求时，如何将子项保存在现有父项中？

Question

我正在尝试执行 POST 请求以将子项(章节)保存到父项(User)上，但它不起作用。

所有其他请求都工作正常。 PostMapping Controller 将 Body 保存到数据库中，但不保存父关系(在我的例子中，类 Chapter → user_id = null)。

我在 Postman 中使用以下 URL:

http://localhost:8080/api/chapters?username=admin
Content-type: application/json
Body: raw

有了这个 body :

{
    "name": "Product Development", 
}

Username: "admin" with Id= 1

<小时/>

@Entity
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(nullable = false, updatable = false)
private Long id;

@Column(nullable = false, unique = true)
private String username;

@Column(nullable = false)
private String password;

@Column(nullable = false)
private String role;

@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "user")
private Set<Chapter> chapters = new HashSet<>();

public void addChapter(Chapter chapter) {
    this.chapters.add(chapter);
    chapter.setUser(this);
}
....
}

@Entity
public class Chapter {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(nullable = false, updatable = false)
private Long id;
    private String name;
@ManyToOne
@JoinColumn(name = "user_id")
private User user;
....

}

@RestController
public class ChapterController {
@Autowired
private ChapterRepository chapterRepository;

@Autowired
private UserRepository userRepository;


@RequestMapping("/chapters")
public Iterable<Chapter> getChapter() {
    return chapterRepository.findAll();
}

@RequestMapping(value="/users/{id}/chapters", method = RequestMethod.GET)
Chapter getChapter(@PathVariable (value = "id") Long id) {
    return chapterRepository.findByUserId(id).get();
}

@PostMapping("/chapters")// issue is here
void newChapter(@RequestParam (value = "username", required=true) 
String username, @RequestBody Chapter newChapter) {
    User user = userRepository.findByUsername(username);
    user.addChapter(newChapter);
    System.out.println(user);
    userRepository.save(user);
    }
}

我希望将子级与父级一起保存，这意味着 user_id = 1 因为目前只有一个用户 (id = 1)。我错过了什么？

Answer 1

您必须为 @ManyToOne 映射添加级联。 在您的用户 @Entity 中更新此行，它将起作用:

@Entity
public class Chapter {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(nullable = false, updatable = false)
    private Long id;

    private String name;

    @ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH})
    @JoinColumn(name = "user_id")
    private User user;

}

您可能想做的第二件事是更新您的 Controller ，因此它将用户 ID 分配给您的新章节，就像这样:

@PostMapping("/chapters")// issue is here
void newChapter(@RequestParam (value = "username", required=true)
                        String username, @RequestBody Chapter newChapter) {
    User user = userRepository.findByUsername(username);
    newChapter.setUser(user);
    user.addChapter(newChapter);
    System.out.println(user);
    userRepository.save(user);
}