春季数据JPA中的嵌套一对多问题

Question

表：survey(id, title);survey_question(id, survey_id, title);survey_question_option(id, survey_question_id, content)实体：@Entitypublic class Survey implements Serializable {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    private Long id;    private String title;    @OneToMany(mappedBy = "survey", fetch = FetchType.EAGER, orphanRemoval = true, cascade = CascadeType.ALL)    private List<SurveyQuestion> questions;}@Entitypublic class SurveyQuestion implements Serializable {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    private Long id;    @JoinColumn(nullable = false)    @ManyToOne    @JsonIgnore    private Survey survey;    private String title;    @OneToMany(mappedBy = "surveyQuestion", fetch = FetchType.EAGER, orphanRemoval = true, cascade = CascadeType.ALL)    private List<SurveyQuestionOption> options;}@Entitypublic class SurveyQuestionOption implements Serializable {    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    private Long id;    @JoinColumn(nullable = false)    @ManyToOne    @JsonIgnore    private SurveyQuestion surveyQuestion;    private String content;}现在添加调查@PostMapping@ResponseStatus(HttpStatus.CREATED)public Survey create(@RequestBody Survey survey) {    return repository.save(survey);}请求正文中的 JSON{    "title": "I'm a survey!",    "questions": [{        "title": "I'm a question!",        "options": [{            "content": "I'm an option."        },        {            "content": "I'm an option."        },        {            "content": "I'm an option."        },        {            "content": "I'm an option."        }]    },    {        "title": "I'm a question!",        "options": [{            "content": "I'm an option."        },        {            "content": "I'm an option."        },        {            "content": "I'm an option."        },        {            "content": "I'm an option."        }]    }]}

Answer 1

您正在同时用于两者fetch = FetchType.EAGER

private List<SurveyQuestion> questions;

和

private List<SurveyQuestionOption> options;

因此，默认情况下，您始终在此处获取整个树。

现在，这里的关键是您将这些依赖项声明为 .这意味着有序但允许重复。在这里，您可以获得每个选项数量的重复问题。List

尝试使用或避免重复。SetSortedSet