java - 响应为空

Question

当我这样做的时候

GET /survey/1

尽管我的数据库中有问题和答案，但我收到了此回复:

{
  "surveyId": 1,
  "name": "Example",
  "questions": null,
  "answers": null
}

为什么我的“问题”和“答案”为空？我该如何解决它？

调查存储库:

public interface SurveyRepository extends CrudRepository<Survey, Integer> { }

调查的模型类:

@Entity
@Table(name = "survey")
public class Survey {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "surveyId")
    private Integer surveyId;

    @Column(name = "name", nullable = false)
    private String name;

    @Transient
    private List<String> questions;

    @Transient
    private List<String> answers;

    public Survey() { }

    public Survey(Integer surveyId, String name) {
        this.surveyId = surveyId;
        this.name = name;
    }

    public Integer getSurveyId() {
        return surveyId;
    }

    public String getName() {
        return name;
    }

    public List<String> getQuestions() {
        return questions;
    }

    public List<String> getAnswers() {
        return answers;
    }

    public void setSurveyId(Integer surveyId) {
        this.surveyId = surveyId;
    }

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

    public void setQuestions(List<String> questions) {
        this.questions = questions;
    }

    public void setAnswers(List<String> answers) {
        this.answers = answers;
    }
}

调查的 Controller 类:

@RestController
@RequestMapping("/survey")
public class SurveyController {

    @Autowired
    private SurveyRepository surveyRepo;

    @Autowired
    private AnswerRepository answerRepo;

    @Autowired
    private QuestionRepository questionRepo;

    @RequestMapping(method = RequestMethod.GET, value = "/{id}")
    public Survey getSurveyById(@PathVariable("id") int id) {
        return surveyRepo.findOne(id);
    }

    @RequestMapping(method = RequestMethod.POST)
    public String create(@RequestBody Survey survey) {
        surveyRepo.save(survey);
        return "Survey created";
    }

    @RequestMapping(method = RequestMethod.GET)
    public Iterable<Survey> getAllSurveys() {
        return surveyRepo.findAll();
    }

    @RequestMapping(method = RequestMethod.DELETE, value = "/{id}")
    public String delete(@PathVariable("id") int id) {
        surveyRepo.delete(id);
        return "Survey deleted";
    }

    @RequestMapping(method = RequestMethod.PUT, value = "/{id}")
    public String update(@PathVariable("id") int id, @RequestBody Survey survey) {
        Survey update = surveyRepo.findOne(id);

        update.setName(survey.getName());
        update.setQuestions(survey.getQuestions());

        surveyRepo.save(update);
        return "Survey updated";
    }

}

回答模型类:

@Entity
@Table(name = "answer")
public class Answer {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "answerId")
    private Integer answerId;

    @Column(name = "answer", nullable = false)
    private String answer;

    @ManyToOne
    @JoinColumn(name = "questionId", nullable = false)
    private Question questionId;

    public Answer() { }

    public Answer(Integer answerId, String answer, Question questionId) {
        this.answerId = answerId;
        this.answer = answer;
        this.questionId = questionId;
    }

    public Integer getAnswerId() {
        return answerId;
    }

    public String getAnswer() {
        return answer;
    }

    public Question getQuestionId() {
        return questionId;
    }

    public void setAnswerId(Integer answerId) {
        this.answerId = answerId;
    }

    public void setAnswer(String answer) {
        this.answer = answer;
    }

    public void setQuestionId(Question questionId) {
        this.questionId = questionId;
    }

}

问题模型类

@Entity
@Table(name = "question")
public class Question {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "questionId")
    private Integer questionId;

    @Column(name = "question", nullable = false)
    private String question;

    @ManyToOne
    @JoinColumn(name = "surveyId", nullable = false)
    private Survey surveyId;

    @Transient
    private List<String> answers;

    public Question() { }

    public Question(Integer questionId, String question, Survey surveyId) {
        this.questionId = questionId;
        this.question = question;
        this.surveyId = surveyId;
    }

    public Integer getQuestionId() {
        return questionId;
    }

    public String getQuestion() {
        return question;
    }

    public Survey getSurveyId() {
        return surveyId;
    }

    public void setQuestionId(Integer questionId) {
        this.questionId = questionId;
    }

    public void setQuestion(String question) {
        this.question = question;
    }

    public void setSurveyId(Survey surveyId) {
        this.surveyId = surveyId;
    }
}

Answer 1

您将它们标记为@Transient，这取决于您使用的是哪一个，这意味着它不会被序列化，或者不会存储在数据库中。请参阅this answer.另外，不相关的您可能应该在这些 Lists

上使用 @ElementCollection(targetClass = String.class)