使用外键保存对象不会在数据库中返回 ID

如何解决使用外键保存对象不会在数据库中返回 ID

我有一个电影院预订系统，用户可以在其中添加电影，然后他们可以为每部电影添加日期。它工作正常，但是当用户添加日期时，没有错误，但它以movie_id = null 保存到数据库中。

我该如何解决？

电影.java

@Data
@Entity
public class Movie {

    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Id
    @Column(name = "id")
    private Long id;

    @Column(unique = true)
    private String title;
 
    private String category;

    @Column( columnDeFinition = "TEXT")
    private String description;

    private Integer lenght;

    private Integer minAge;

    @Column(columnDeFinition = "TEXT")
    private String imageUrl;

    @OnetoMany(mappedBy = "movie",orphanRemoval = true)
    private List<Repertoire> repertoires;

    public Movie() {
   }
}

Repertoire.java

@Data
@Entity
public class Repertoire {

    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Id
    @Column(name = "id")
    private Long id;

    @DateTimeFormat(pattern = "yyyy-MM-dd'T'HH:mm")
    private LocalDateTime date;

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "movie_id")
    private Movie movie;
}

电影控制器.java

@Controller
@RequestMapping("/movies")
public class MovieController {

    private MovieRepo movieRepo;
    private RepertoireRepo repertoireRepo;

    @Autowired
    public MovieController(MovieRepo movieRepo,RepertoireRepo repertoireRepo) {
        this.movieRepo = movieRepo;
        this.repertoireRepo = repertoireRepo;
    }

    @GetMapping("showForm")
    public String showStudentForm(Movie movie) {
        return "add-movie";
    }

    @GetMapping("list")
    public String getMovies(Model model) {
        model.addAttribute("movies",movieRepo.findAll());
        return "movieIndex";
    }

    @PostMapping("add")
    public String movies(@Validated Movie movie,BindingResult result,Model model) {
        if(result.hasErrors()) {
            return "add-movie";
        }

        movieRepo.save(movie);
        return "redirect:/movies/list";
    }

    @GetMapping("edit/{id}")
    public String showUpdateForm(@PathVariable ("id") long id,Model model) {
        Movie movie = movieRepo.findById(id)
                .orElseThrow(() -> new IllegalArgumentException("Nieprawidłowe ID: " + id));

        model.addAttribute("movie",movie);
        return "update-movie";
    }

    @PostMapping("update/{id}")
    public String updateMovie(@PathVariable("id") long id,@Validated Movie movie,Model model) {
        if(result.hasErrors()) {
            movie.setId(id);
            return "update-movie";
        }
        movieRepo.save(movie);

        model.addAttribute("movies",movieRepo.findAll());
        return "movieIndex";
    }

    @GetMapping("delete/{id}")
    public String deleteMovie(@PathVariable ("id") long id,Model model) {

        List<Repertoire> repertoires = repertoireRepo.findByMovieId(id);
        repertoires.forEach(r -> repertoireRepo.deleteById(r.getId()));

        Movie movie = movieRepo.findById(id)
                .orElseThrow(() -> new IllegalArgumentException("Nieprawidłowe ID : " + id));

        movieRepo.delete(movie);
        model.addAttribute("movies",movieRepo.findAll());
        return "movieIndex";

    }



// HERE'S WHERE I ADD THE TIME:

    @GetMapping("/admin/{movieName}/newRepertoire")
    public String showRepertoireForm(Model model,@PathVariable ("movieName") String movieName) {

        Movie movieRepertoire = movieRepo.findByTitle(movieName);
        model.addAttribute("movieRepertoire",movieRepertoire);
        model.addAttribute("repertoire",new Repertoire());
        return "repertoire";
    }

    @PostMapping("/admin/newRepertoire")
    @Transactional
    public String addRepertoire(@modelattribute ("repertoire") Repertoire repertoire,@modelattribute("movieRepertoire") Movie movie,BindingResult result) {
//        if(result.hasErrors()) {
//            return "repertoire";
//        }


        repertoire.setMovie(movieRepo.findByTitle(movie.getTitle()));
        repertoireRepo.save(repertoire);
        return "redirect:/movies/list";
    }
}

RepertoireRepo.java

@Repository
public interface RepertoireRepo extends JpaRepository<Repertoire,Long> {
    List<Repertoire> findByMovieId(Long movieId);
}

MovieRepo.java

@Repository
public interface MovieRepo extends JpaRepository<Movie,Long> {
    Movie findByTitle(String title);
}

repertoire.html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org"
      xmlns:sec="http://www.thymeleaf.org/extras/spring-security">

<head>
    <Meta charset="UTF-8">
    <Meta http-equiv="x-ua-compatible" content="ie=edge">
    <title>c</title>
</head>
<body>

<div class="container my-5">
    <div class="card">
        <div class="card-body">
            <div class="col-md-10">
                <h1 th:text="${movieRepertoire.title}"> MovieName</h1>
                <form action="#" th:action="@{/movies/admin/newRepertoire}" th:object="${repertoire}" method="post">
                    <div class="row">
                        <div class="form-group col-md-8">
                            <label for="date" class="col-form-label">Date</label>
                            <input type="datetime-local" th:field="*{date}" class="form-control" id="date" value="2021-01-20T13:01">
                            <span th:if="${#fields.hasErrors('date')}" th:errors="*{date}" class="text-danger"></span>
                        </div>
                        <div class="col-md-6">
                            <input type="submit" class="btn btn-primary" value="Add">
                        </div>
                        <div class="form-group col-md-8"></div>
                    </div>
<!--                    <input type = "hidden" th:value="${movieRepertoire}">-->
                </form>
            </div>
        </div>
    </div>
</div>
</body>
</html>

电影结构：

id | category | description | imageurl| lenght| minage| title
 ------------------------- 
36 | Action | Simple desc. | photo.jpg | 137 | 7 | Iron Man |

曲目结构：

id | date | movie_id
------------------------- 
37 | 2021-01-01 14:00:00 | null |

解决方法

关系的双方都必须更新，您应该从父级级联保存。您的代码：

    repertoire.setMovie(movieRepo.findByTitle(movie.getTitle()));
    repertoireRepo.save(repertoire);

应该变成：

    Movie movie = movieRepo.findByTitle(movie.getTitle());
    movie.getRepertoires().add(repertoire);
    repertoire.setMovie(movie);
    session.saveOrUpdate(movie);

实际上，您应该向 Movie 添加一个辅助方法，该方法执行两个操作以确保关系的双方始终同步：

public void addRepertoire(Repertoire repertoire) {
  repertoires.add(repertoire);
  repertoire.setMovie(this);
}