共有三个类（课程、课程、用户）。
@EqualsAndHashCode(callSuper = true)
@Entity
@Table(name = "usr")
@Data
public class User extends RepresentationModel<User> implements UserDetails {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String firstname;
private String lastname;
private String username;
private String password;
@ElementCollection(targetClass = ERole.class, fetch = FetchType.EAGER)
@CollectionTable(name = "user_role", joinColumns = @JoinColumn(name = "user_id"))
@Enumerated(EnumType.STRING)
private Set<ERole> roles;
}
@Data
@Entity
@NoArgsConstructor
public class Lesson extends RepresentationModel<Lesson> {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private String startTime;
private String endTime;
private String dayOfWeek;
@ManyToOne
private User teacher;
}
@EqualsAndHashCode(callSuper = true)
@Data
@Entity
public class Course extends RepresentationModel<Course> {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private Date startDate;
private Date endDate;
private String name;
@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private Set<User> teachers;
@ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private Set<User> students;
private String description;
@ManyToMany(cascade = CascadeType.ALL)
private Set<Lesson> lessons;
}
还有 RestController ( CoursesController)。在 /courses 访问服务器时，我得到所有字段的正确服务器响应
.
@RestController
@RequestMapping("/courses")
public class CoursesController {
private final CourseService courseService;
private final UserService userService;
private final LessonService lessonService;
@Autowired
public CoursesController(CourseService courseService, UserService userService, LessonService lessonService) {
this.courseService = courseService;
this.userService = userService;
this.lessonService = lessonService;
}
@GetMapping
@Operation(
summary = "getAllCourses",
description = "Returns all available courses"
)
public ResponseEntity<Page<Course>> getAllCourses(@PageableDefault(sort = "id", size = 5) Pageable pageable) {
try {
Page<Course> coursePage = courseService.findAll(pageable);
for (Course course : coursePage.getContent())
course.add(linkTo(methodOn(CoursesController.class).getCourse(course.getId().toString())).withSelfRel());
return ResponseEntity.ok(courseService.findAll(pageable));
}
catch (Exception e) {
return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
}
}
@GetMapping("/{course-id}")
@Operation(
summary = "getCourse",
description = "Returns course by ID"
)
public ResponseEntity<Course> getCourse(@PathVariable ("course-id") String courseId) {
try {
Course course = courseService.getCourseById(courseId);
course.add(linkTo(methodOn(CoursesController.class).getCourse(courseId)).withSelfRel());
return ResponseEntity.ok(course);
} catch (Exception e) {
return new ResponseEntity<>(HttpStatus.NOT_FOUND);
}
}
}
为什么在通过 ID (GET /courses/{id}) 请求课程时，Spring 会返回一个不完整的对象（尽管我手动添加了多个教师、学生和课程）？
我需要获取对象的所有字段。我的 CourseRepository 下面。
@Repository
@Transactional
public interface CourseRepository extends JpaRepository<Course, Long> {
}
我的 CourseService 下面。
@Service
public class CourseService {
private final CourseRepository courseRepository;
private final LessonRepository lessonRepository;
private final UserRepository userRepository;
@Autowired
public CourseService(CourseRepository courseRepository, LessonRepository lessonRepository, UserRepository userRepository) {
this.courseRepository = courseRepository;
this.lessonRepository = lessonRepository;
this.userRepository = userRepository;
}
public Page<Course> findAll(Pageable pageable) {
return courseRepository.findAll(pageable);
}
public Course createCourse(CourseDto courseDto) {
Course course = new Course(courseDto.getStartDate(), courseDto.getEndDate(), courseDto.getName(), courseDto.getDescription());
return courseRepository.saveAndFlush(course);
}
public Optional<Course> getCourseById(String id) {
return courseRepository.findById(Long.parseLong(id));
}
public Course updateCourse(CourseDto courseDto, String id) {
Course course = courseRepository.findById(Long.parseLong(id)).get();
course.setStartDate(courseDto.getStartDate());
course.setEndDate(courseDto.getEndDate());
course.setName(courseDto.getName());
course.setDescription(courseDto.getDescription());
return courseRepository.saveAndFlush(course);
}
public Page<Lesson> getLessonsByCourse(String courseId, Pageable pageable) {
Course course = courseRepository.findById(Long.parseLong(courseId)).get();
return new PageImpl<>(new ArrayList<>(course.getLessons()), pageable, course.getLessons().size());
}
public Course addLesson(String courseId, LessonDto lessonDto) {
Course course = courseRepository.findById(Long.parseLong(courseId)).get();
Lesson lesson = new Lesson();
lesson.setStartTime(lessonDto.getStartTime());
lesson.setEndTime(lessonDto.getFinishTime());
lesson.setDayOfWeek(lessonDto.getDayOfWeek());
lesson.setTeacher(userRepository.getUserById(lessonDto.getTeacherId()));
lessonRepository.saveAndFlush(lesson);
System.out.println(lesson);
course.getLessons().add(lesson);
return courseRepository.saveAndFlush(course);
}
public void deleteCourse(String id) {
courseRepository.deleteById(Long.parseLong(id));
}
}