Hibernate和Spring：多对多的值不插入到生成的表中 [英] Hibernate and Spring: value of many-to-many not inserted into generated table

问题描述

我对Spring有一些经验，但对于Hibernate来说，我完全是新手，特别是与Spring结合使用：
我想在两个表之间建立多对多关系（作者，出版物）。表格已生成，但没有插入任何内容......

Author.java的一部分：

  @ManyToMany（cascade = {CascadeType.ALL}）
 @JoinTable（name =writes，joinColumns = {@JoinColumn（name =authorId）}，inverseJoinColumns = {@JoinColumn （name =publicationId）}）
 private Set< Publication> publications = new HashSet< Publication>（）; 
  

部分Publication.java：

  @ManyToMany（mappedBy =publications）
 private Set< Author> authors = new HashSet< Author>（）; 
  

有没有我忘记的东西？

谢谢!!!!

编辑

以下是将所有内容保存到我的数据库的代码：

  @RequestMapping（value = PATHELEM + / insertTest，method = RequestMethod.POST）
 public String addAuthor（@ModelAttribute（object）DatabaseObject object，
 BindingResult result）{
 authorService.addAuthor（object.getAuthor（） ）; 
 publicationService.addPublication（object.getPublication（））; 
 return PATHELEM +/ insertEntryForm; 
 
  

解决方案

：

• 将您的实体与会话相关联。如果你只是创建你的对象，hibernate不知道是否将它们保存到数据库。这就是为什么你应该调用 session.save（..） / entityManager.persist（..）（取决于是否您使用JPA）。


• 事务 - 在hibernate中的每个操作都需要一个事务，因此您必须通过实体管理器/ session

我建议阅读一个教程，它将解释这些基本原则。

I've got a bit of experience with spring, but I'm completely new to Hibernate, especially in combination with Spring: I want to have a Many-to-Many relationship between two tables (author, publication). The table is generated, but nothing is inserted...

Part of Author.java:

@ManyToMany(cascade = {CascadeType.ALL})
@JoinTable(name = "writes", joinColumns = {@JoinColumn(name = "authorId")}, inverseJoinColumns = {@JoinColumn(name = "publicationId")})
private Set<Publication> publications = new HashSet<Publication>();

part of Publication.java:

@ManyToMany(mappedBy = "publications")
private Set<Author> authors = new HashSet<Author>();

Is there something I forgot?

Thanks!!!!

Edit

here's the code which should save everything to my database:

@RequestMapping(value = PATHELEM + "/insertTest", method = RequestMethod.POST)
public String addAuthor(@ModelAttribute("object") DatabaseObject object,
        BindingResult result) {
    authorService.addAuthor(object.getAuthor());
    publicationService.addPublication(object.getPublication());
    return PATHELEM + "/insertEntryForm";
}

解决方案

You are missing two important things:

• associating your entities with a session. If you just create your objects, hibernate can't know whether to save them to db. That's why you should call session.save(..) / entityManager.persist(..) (depending on whether you use JPA).
• transaction - every manipulation in hibernate needs a transaction, so you have to start one via the entity manager / session

I'd suggest reading a tutorial, which will explain these basic principles.

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