java - json 序列化中缺少 Jackson Spring 字段

Question

此 Question 类的 json 序列化中缺少 Action 字段。我知道我正在查询的问题有一些操作，因为我在 Controller 返回问题对象之前查看了问题对象

@Entity
@Table
@Data
public class Question {

    @Id
    @GeneratedValue
    @Column
    private int id;

    @Column
    private String text;

    @Column
    private double weight;

    @Enumerated(EnumType.STRING)
    private TeamType teamType;

    @Column
    private Category cat;

    @ManyToOne
    @JsonBackReference(value="act-ques")
    private Action action;

    @OneToMany
    @JsonManagedReference(value="ques-resps")
    private Set<Response> response;

}

这是 Action 类

@Entity
@Table
@Data
public class Action {

    @Id
    @Column
    @GeneratedValue
    private Long id;

    @Enumerated(EnumType.STRING)
    private ActionType actionType;

    @Enumerated(EnumType.STRING)
    private Category cat;

    @OneToMany
    @Fetch(FetchMode.JOIN)
    @JsonManagedReference(value="act-ques")
    private Set<Question> questions;
}

我有一个 ActionController，它返回该类的 json 字符串。为什么问题的 json 中缺少 Action 类？

这是 ActionController

@RestController
@RequestMapping("api/actions")
public class ActionController {

    @Autowired
    private ActionService actService;

    @GetMapping
    public List<Action> getActions(@RequestParam Map<String, Object> params) {
        List<Action> actions = actService.getAll();
        return actions;
    }
}

这是问题 Controller 。当我在其中放置断点时，我可以看到问题对象中的操作，但返回的 json 没有它们的字段

@RestController
@RequestMapping("api/questions")
public class QuestionController {

    @Autowired
    private QuestionService questionService;

    @GetMapping
    public List<Question> getQuestions(@RequestParam Map<String, Object> params) {
        List<Question> questions = questionService.getQuestions(params);
        return questions;
    }

}

Answer 1

这是因为你正在使用

@JsonBackReference(value="act-ques")
private Action action;

请引用此blog

@JsonManagedReference is the forward part of reference – the one that gets serialized normally.
@JsonBackReference is the back part of reference – it will be omitted from serialization.