Spring JpaRepository 不会删除表中的行

Question

I'm using postgresql and have 2 classes. User:

@Entity
@Table(name="usr") //
public class User implements UserDetails {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
}

And Post

@Entity
public class Post {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "user_id")
    private User author;
}

When I try to delete post by id Hibernate set all fields in null except user_id and not deleting. I've tried adding @Query in PostRepository

@Modifying(clearAutomatically = true, flushAutomatically = true)
@Query(value = "DELETE FROM post WHERE id = ?1", nativeQuery = true)
void deleteById(long postId);

Tried adding @OneToMany in User. Tried different FetchType, but nothing helps.

PostRepository:

@Repository
public interface PostRepository extends JpaRepository<Post, Long> {

}

Delete post like this:

@DeleteMapping("/{id}")
public String blogPostDelete(@PathVariable("id") long id) {
    postRepository.deleteById(id);
    return "redirect:/blog";
}

I'm almost shure there's something wrong in @ManyToOne but can't understand what exactly

Answer 1

You can try to add @Transactional annotation above your custom query.
If result still will be the same you can find something in my working code. Deleting was working:

Parent:

@Entity
@Table(name = "users")
public class EntityUser {

    @Id
    @Column(name = "uuid_user", length = 16, unique = true, nullable = false)
    private final UUID uuid = UUID.randomUUID();

    @OneToMany(targetEntity=EntityNote.class, mappedBy = "owner", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    private List<EntityNote> noteList = new ArrayList<>();
}

And child:

@Entity
@Table(name = "notes")
public class EntityNote {
   
    @Id
    @Column(name = "uuid_note", length = 16, unique = true, nullable = false)
    private UUID uuid = UUID.randomUUID();
   
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "owner")
    private EntityUser owner;
}

You can try to do similar relation and check it will works and remodel for your requirements.

Answer 2

In your controller, try to fetch the record first using the 'id'

Post post = postRepository.findById(id)

then use the return Post object and call delete. No need to create such native query, JpaRepository (CrudRepository) has the basic built in functions you need

postRepository.delete(post)

Answer 3

When working with Hibernate, it is interesting to put objects in session, whenever you want to perform any operation.

So, try load you User object and remove the post with user.getListofPosts().remove(post.getId()).

After that, update your user object.

This should be done within your operation annotated with @Transactional.