JPA（休眠）onetomany关系(JPA (hibernate) onetomany relation)

 我不确定我想要做什么双向onetomany关系（休眠引擎）。 域模型的缩小版本： 
 
class Person {
@OneToMany(mappedBy="personFrom", cascade = CascadeType.PERSIST)
    public List<Relationship> relationships;
}

class Relationship {
@ManyToOne
  public Person personFrom;

  @ManyToOne
  public Person personTo;
}
 
 一些观察结果： 
 1.使用上面的映射，没有创建连接表。 
 2.当我删除mappedBy（@OneToMany（cascade = CascadeType.PERSIST））时，创建了连接表，我可以通过Person持久保存。 “personFrom”字段为空，但我认为这是正常的，因为通过连接表维护关系。 
 
 我也尝试通过在关系中指定连接列，没有任何区别。 任何帮助，高度赞赏。 谢谢。 
 
 编辑：1 
 
 根据Dan的评论，如果看到域类的完整内容很重要，我已在下面进行了扩展。 
 
class Relationship extends Model{

  @ManyToOne
  public RelationshipType relationshipType;

  @ManyToOne
  public Person personFrom;

  @ManyToOne
  public Person personTo;

  @ManyToOne
  public Person createdBy;

  @ManyToOne
  public Role roleFrom;

  @ManyToOne
  public Role roleTo;

    @Override
    public String toString() {
        return relationshipType.toString();
    }
}

class Person extends Model {

    public Date dateCreated;

    @Lob
    public String description;

    @OneToMany(cascade = CascadeType.ALL)
    public List<Role> roles;

    @OneToMany(mappedBy="personFrom", cascade = CascadeType.PERSIST)
    public List<Relationship> relationships;
}
 
 角色也与Person有关，但我认为保持personFrom，personTo有助于优化我的查询。 
 
Role extends Model {

    @ManyToOne
    public RoleType roleType;

    @ManyToOne
    public Person createdBy; 
}

I am not sure what I am missing to make a bidirectional onetomany relationship (hibernate engine). A scaled down version of the domain model:
 
class Person {
@OneToMany(mappedBy="personFrom", cascade = CascadeType.PERSIST)
    public List<Relationship> relationships;
}

class Relationship {
@ManyToOne
  public Person personFrom;

  @ManyToOne
  public Person personTo;
}
 
Some of the observations:
 1. with the above mapping, there is no join table created.
 2. When I remove the mappedBy (@OneToMany(cascade = CascadeType.PERSIST) ), the join table is created and i could persist Relationship through Person. "personFrom" field is empty, but I think that is normal as the relation is maintained through the join table. 
 
I also tried by specifying join column at Relationship, didn't make any difference. Any help, highly appreciated. thanks.
 
Edit:1
 
As per Dan's comment, if it matters to see the full content of the domain class, I have expanded them below.
 
class Relationship extends Model{

  @ManyToOne
  public RelationshipType relationshipType;

  @ManyToOne
  public Person personFrom;

  @ManyToOne
  public Person personTo;

  @ManyToOne
  public Person createdBy;

  @ManyToOne
  public Role roleFrom;

  @ManyToOne
  public Role roleTo;

    @Override
    public String toString() {
        return relationshipType.toString();
    }
}

class Person extends Model {

    public Date dateCreated;

    @Lob
    public String description;

    @OneToMany(cascade = CascadeType.ALL)
    public List<Role> roles;

    @OneToMany(mappedBy="personFrom", cascade = CascadeType.PERSIST)
    public List<Relationship> relationships;
}
 
Role also related to Person, but I think keeping the personFrom, personTo helps to optimize my queries.
 
Role extends Model {

    @ManyToOne
    public RoleType roleType;

    @ManyToOne
    public Person createdBy; 
}

原文：https://stackoverflow.com/questions/3346154