Question

@RestController
public class TopicController {

    @Autowired
    private TopicService topicService;

    @RequestMapping(value="/topics", method= RequestMethod.GET)
    public List<Topic> getAllTopics(){
        return topicService.getAllTopics();
    }

    @RequestMapping(value="/topics/{id}", method= RequestMethod.GET)
    public Topic getTopic(@PathVariable String id){
        return topicService.getTopic(id);
    }

    @RequestMapping(value="/topics", method= RequestMethod.POST)
    public void addTopic(@RequestBody Topic topic){
        topicService.addTopic(topic);
    }

    @RequestMapping(value="/topics/{id}", method= RequestMethod.PUT)
    public void updateTopic(@RequestBody Topic topic, @PathVariable String id){
        topicService.updateTopic(id, topic);
    }

    @RequestMapping(value="/topics/{id}", method= RequestMethod.DELETE)
    public void deleteTopic(@PathVariable String id){
        topicService.deleteTopic(id);
    }
}

控制器类

@Service
public class TopicService {

    @Autowired
    private TopicRepository topicRepo;

    public List<Topic> getAllTopics(){
        return (List<Topic>)topicRepo.findAll();

    }

    public Topic getTopic(String id){
        return topicRepo.findOne(id);
    }

    public void addTopic(Topic topic){
        //topics.add(topic);

        topicRepo.save(topic);
    }

    public void updateTopic(String id, Topic topic) {
        topicRepo.save(topic);
    }

    public void deleteTopic(String id) {
        //topics.removeIf(t -> t.getId().equals(id));

        //topics.removeIf((Topic t) -> t.getId().equals(id));

        topicRepo.delete(id);

    }

}

服务类

@Repository
public interface TopicRepository extends CrudRepository<Topic, String>{

    //List<Course> findByTopic_Id(String topicid);

}

存储库类

@Entity
public class Topic {

    @Id
    @Column(name="TOPIC_ID")
    private String id;
    @Column(name="NAME")
    private String name;
    @Column(name="DESCRIPTION")
    private String description;

    @OneToMany(mappedBy="topic", fetch = FetchType.EAGER)
    @JsonManagedReference
    private List<Course> course = new ArrayList<Course>();

    //no - argument constructor. Needed for hibernate
    public Topic(){};

    public Topic(String id, String name, String description, List<Course> course){
        super();
        this.id = id;
        this.name = name;
        this.description = description;
        this.course = course;
    }

    public Topic(String id, String name, String description){
        super();
        this.id = id;
        this.name = name;
        this.description = description;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public List<Course> getCourse() {
        return course;
    }

    public void setCourse(List<Course> course) {
        this.course = course;
    }
}

主题类

@Entity
public class Course{

    @Id
    @Column(name="COURSE_ID")
    private String id;
    private String name;
    private String description;

    //There could be many courses related to 1 topic
    @ManyToOne
    @JoinColumn(name = "TOPIC_ID")
    @JsonBackReference
    private Topic topic;

    public Course(){};


    public Course(String id, String name, String description){

        super();
        this.id = id;
        this.name = name;
        this.description = description;

    }

    public Topic getTopic() {
        return topic;
    }

    public void setTopic(Topic topic) {
        this.topic = topic;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

}

课程班

我正在尝试使用Postman将包含许多课程的Topic类发布到我的sql数据库中。

在Postman中，我使用像这样的JSON进行POST

{
    "id": "700",
    "name": "How to countt",
    "description": "Counting numbersssss",
    "course": [
      {
        "id": "1",
        "name": "php",
        "description": "gooddddyyyy stuff"
      },
      {
        "id": "2",
        "name": "phpp",
        "description": "gooddddyyyy stuffp"
      }
    ]
}

然而，当我做相应的获取所有主题时，我的回答是

{
    "id": "700",
    "name": "How to countt",
    "description": "Counting numbersssss",
    "course": []
}

它没有拿起我发布的课程。一个主题可以有很多课程。我该如何解决？谢谢

Answer 1

您永远不会设置双向关联的拥有方：Course.topic。

Topic.courses上没有级联设置。

因此，不仅保存主题不会保存其课程，但即使这样做，课程也不属于他们的主题。

POST一个项目列表spring boot

1 个答案: