500 внутренняя ошибка сервера, NullPointerException при получении запроса

Question

Я работаю над проектом весенней загрузки,

Я пытаюсь отправить запрос на получение от почтальона, но я получаю 500 внутренняя ошибка сервера.

Пожалуйста, помогите мне улучшить код.

CONTROLLER:

@RestController
@RequestMapping("/admin")
@CrossOrigin(origins = "http://localhost:4200")
public class sessionMcqController {

@Autowired
private sessionMcqService service;

@GetMapping("/viewmcq")
public List<Question> getAll(){
    return service.getAll();
}

}

Модели:

1. Вопрос Модель:

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

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@JoinColumn (name = "questionId")
private Long questionId;

@Column(nullable = false)
private String question;

@OneToOne(fetch = FetchType.LAZY, targetEntity = Option.class)
@JoinTable( name = "mcq_answer", joinColumns = @JoinColumn ( name = "question_id"), inverseJoinColumns = @JoinColumn( name = "option_id"))
private List <Option> options;

@OneToMany(mappedBy = "questionId", cascade = CascadeType.ALL)
private Set<Option> option;

public Question() { }

public Long getMcqId() {
    return questionId;
}

public void setMcqId(Long mcqId) {
    this.questionId = mcqId;
}

public String getQuestion() {
    return question;
}

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

@Override
public String toString() {
    return "McqModel{" +
            "mcqId=" + questionId +
            ", question='" + question + '\'' +
            '}';
}

@Override
public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    Question question1 = (Question) o;
    return questionId.equals(question1.questionId) &&
            question.equals(question1.question) &&
            options.equals(question1.options) &&
            option.equals(question1.option);
}

@Override
public int hashCode() {
    return Objects.hash(questionId, question, options, option);
}
}

2. OptionModel:

@Entity
@Table(name = "mcq_Options")
public class Option {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "option_id")
private int optionId;

private String option;

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn
private Question questionId;

public Option() { }

public Option(String option, Question questionId) {
    this.option = option;
}

public int getOptionId() {
    return optionId;
}

public void setOptionId(int optionId) {
    this.optionId = optionId;
}

public String getOption() {
    return option;
}

public void setOption(String option) {
    this.option = option;
}

public Question getQuestionId() {
    return questionId;
}

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

@Override
public String toString() {
    return "Option{" +
            "optionId=" + optionId +
            ", option='" + option + '\'' +
            ", questionId=" + questionId +
            '}';
}
}

СКЛАД: 1.QuestionRepository

@Repository
public interface QuestionRepository extends JpaRepository<Question, Long> {
}

2.OptionRepository

@Repository
public interface OptionRepository extends JpaRepository<Option, Integer> {
}

СЕРВИС

@Service
public class sessionMcqService {

@Autowired
private QuestionRepository repository;

public List<Question> getAll(){

    return repository.findAll();
}

}

ОШИБКА:

java.lang.NullPointerException: null в com.bluepi.TrainingProject.controller.sessionMcqController.getAll (sessionMcqController.java:22) ~ [classes /: na] at sun.reflect.NativeMethodAccessorImpl.invoke0 (собственный метод) ~ [na: 1.8.0_201] at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62) ~ [na: 1.8.0_201] at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43) ~ [na: 1.8.0_201] at java.lang.reflect.Method.invoke (Method.java:498) ~ [na: 1.8.0_201] в org.springframework.web.method.support.InvocableHandlerMethod.doInvoke (InvocableHandlerMethod.java:189) ~ [spring-web-5.1.5.RELEASE.jar: 5.1.5.RELEASE] в org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest (InvocableHandlerMethod.java:138) ~ [spring-web-5.1.5.RELEASE.jar: 5.1.5.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle (ServletInvocableHandlerMethod.java:102) ~ [spring-webmvc-5.1.5.RELEASE.jELE: 5.1.5. at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod (RequestMappingHandlerAdapter.java:895) ~ [spring-webmvc-5.1.5.RELEASE.jar: 5.1.5.RELEASE] at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal (RequestMappingHandlerAdapter.java:800) ~ [spring-webmvc-5.1.5.RELEASE.jar: 5.1.5.RELEASE] at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle (AbstractHandlerMethodAdapter.java:87) ~ [spring-webmvc-5.1.5.RELEASE.jar: 5.1.5.RELEASE] в org.springframework.web.servlet.DispatcherServlet.doDispatch (DispatcherServlet.java:1038) ~ [spring-webmvc-5.1.5.RELEASE.jar: 5.1.5.RELEASE] в org.springframework.web.servlet.DispatcherServlet.doService (DispatcherServlet.java:942) ~ [spring-webmvc-5.1.5.RELEASE.jar: 5.1.5.RELEASE] в org.springframework.web.servlet.FrameworkServlet.processRequest (FrameworkServlet.java:1005) ~ [spring-webmvc-5.1.5.RELEASE.jar: 5.1.5.RELEASE] в org.springframework.web.servlet.FrameworkServlet.doGet (FrameworkServlet.java:897) ~ [spring-webmvc-5.1.5.RELEASE.jar: 5.1.5.RELEASE] в javax.servlet.http.HttpServlet.service (HttpServlet.java:634) ~ [tomcat-embed-core-9.0.16.jar: 9.0.16] в org.springframework.web.servlet.FrameworkServlet.service (FrameworkServlet.java:882) ~ [spring-webmvc-5.1.5.RELEASE.jar: 5.1.5.RELEASE] в javax.servlet.http.HttpServlet.service (HttpServlet.java:741) ~ [tomcat-embed-core-9.0.16.jar: 9.0.16]

Answer 1

Вам нужно будет добавить @Autowired над строкой private sessionMcqService service; на sessionMcqController.java.