java - ManyToMany Relation 正在更新域表

Question

所以我有一个以这种方式映射的ManyToMany关系:

@ManyToMany(cascade = CascadeType.MERGE)
    @JoinTable( name = "post_category",
        joinColumns = @JoinColumn(name = "post_id"),
        inverseJoinColumns = @JoinColumn(name = "category_id")
    )
    private List<CategoryEntity> post_categories;

然后:

    @ManyToMany(mappedBy = "post_categories")
    private List<PostEntity> posts;

关系应该是这样的:

问题是:我的帖子有类别，这些类别位于静态表中，我不想更改它。我只想更改关系表。 当我第一次保存帖子时它可以工作，但是当我尝试更新帖子时，它会修补应该是静态的表: 更新方法:

    public Post att(Post model, Integer id) throws ResponseStatusException {
        Optional<PostEntity> optionalEntity = repo.findById(id);

        if(!optionalEntity.isPresent()) {
            throw new ResponseStatusException(HttpStatus.NOT_FOUND, "Post not found");
        }

        PostEntity entity = optionalEntity.get();
        entity.setPost_categories(((model.getPost_categories() != null) ? CategoryMapper.marshall(model.getPost_categories()) : entity.getPost_categories()));
        entity.setPost_author((model.getPost_author() != null) ? model.getPost_author() : entity.getPost_author());
        entity.setTitle((model.getTitle() != null) ? model.getTitle() : entity.getTitle());

        return PostMapper.unmarshall(repo.save(entity));    
    }

关系好吗？我做错了什么？？

项目的github链接在这里，https://github.com/moreiravictor/EspatodeAPI/tree/master/src/main/java/br/com/espatodea/espatodeAPI

Answer 1

经过一番搜索，我发现是cascadeType的问题。因此，为了解决这个问题，您只需更改为 REFRESH:

@ManyToMany(cascade = CascadeType.REFRESH)
    @JoinTable( name = "post_category",
        joinColumns = @JoinColumn(name = "post_id"),
        inverseJoinColumns = @JoinColumn(name = "category_id")
    )
    private List<CategoryEntity> post_categories;

REFRESHcascadeType 允许您仅对关系的父级进行更改。这样子(类别)就永远不会改变。