Self referencing symmetrical Hibernate Map Table using @ManyToMany

Posted by sammichy on Stack Overflow See other posts from Stack Overflow or by sammichy
Published on 2010-03-23T15:44:19Z Indexed on 2010/03/23 19:53 UTC
Read the original article Hit count: 620

Filed under:

hibernate

|

manytomany

|

jointable

I have the following class

public class ElementBean {
    private String link;
    private Set<ElementBean> connections;
}

I need to create a map table where elements are mapped to each other in a many-to-many symmetrical relationship.

@ManyToMany(targetEntity=ElementBean.class)
@JoinTable(
    name="element_elements",
    joinColumns=@JoinColumn(name="FROM_ELEMENT_ID", nullable=false),
    inverseJoinColumns=@JoinColumn(name="TO_ELEMENT_ID", nullable=false)
)
public Set<ElementBean> getConnections() {
    return connections;
}

I have the following requirements

When element A is added as a connection to Element B, then element B should become a connection of Element A. So A.getConnections() should return B and B.getConnections() should return A. I do not want to explicitly create 2 records one for mapping A to B and another for B to A.

Is this possible?

© Stack Overflow or respective owner

Related posts about hibernate

Hibernate unable to instantiate default tuplizer - cannot find getter

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm trying to use Hibernate to persist a class that looks like this: public class Item implements Serializable, Comparable<Item> { // Item id private Integer id; // Description of item in inventory private String description; // Number of items described by this inventory item private int… >>> More
Hibernate + PostgreSQL : relation does not exist - SQL Error: 0, SQLState: 42P01

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, I am having some problems trying to work with PostgreSQL and Hibernate, more specifically, the issue mentioned in the title. I've been searching the net for a few hours now but none of the found solutions worked for me. I am using Eclipse Java EE IDE for Web Developers. Build id: 20090920-1017… >>> More
Problem connecting to Hsqldb via Hibernate when running a Eclipse GWT project.

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I'm trying to run a simple GWT project where I'm trying to do a simple persitence via hibernate to a HSQLDB database. The database I'm using I have been using for at least 2 years with several osgi applications without any problems. So all I done is reused the same configuration and added a simple… >>> More
Hibernate : load and

as seen on Stack Overflow - Search for 'Stack Overflow'
According to the tutorial : http://jpa.ezhibernate.com/Javacode/learn.jsp?tutorial=27hibernateloadvshibernateget, If you initialize a JavaBean instance with a load method call, you can only access the properties of that JavaBean, for the first time, within the transactional context in which it… >>> More
Hibernate Exception, what wrong ? [[Exception in thread "main" org.hibernate.InvalidMappingException

as seen on Stack Overflow - Search for 'Stack Overflow'
I use netbean 6.7.1 to write "hello world" witch hibernate, but I get some errors, plz help me, thank you very much. my exception init: deps-module-jar: deps-ear-jar: deps-jar: Copying 1 file to F:\Documents and Settings\My Dropbox\DropboxNetBeanProjects\loginspring\build\web\WEB-INF\classes compile-single: run-main: Oct… >>> More

Related posts about manytomany

Self referencing symmetrical Hibernate Map Table using @ManyToMany

as seen on Stack Overflow - Search for 'Stack Overflow'
I have the following class public class ElementBean { private String link; private Set<ElementBean> connections; } I need to create a map table where elements are mapped to each other in a many-to-many symmetrical relationship. @ManyToMany(targetEntity=ElementBean.class) @JoinTable( … >>> More
Django ManyToMany join query

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm sure this is really simple, but I can't for the life of me find any documentation explaining how to do this. How do I get the results of a ManyToMany field inside a join as opposed to doing this: {% for tag in article.tags.all %} Which results in an extra query? What I'd like to do is fetch… >>> More
django ManyToMany through help

as seen on Stack Overflow - Search for 'Stack Overflow'
Hay I've got a question about relationships. I want to Users to have Friendships. So a User can be a friend with another User. I'm assuming i'll need to use the ManyToManyField, through a Friendship table. But i cannot get it to work. Any ideas? Here are my models. class User(models.Model): … >>> More
Limiting choices from an intermediary ManyToMany junction table in Django

as seen on Stack Overflow - Search for 'Stack Overflow'
Background I've created three Django models—Inventory, SalesOrder, and Invoice—to model items in inventory, sales orders for those items, and invoices for a particular sales order. Each sales order can have multiple items, so I've used an intermediary junction table—SalesOrderItems—using the through… >>> More
What's best practice to check if an object is part of a ManyToMany relationship in Django

as seen on Stack Overflow - Search for 'Stack Overflow'
from an instance of Site with a ManyToMany relationship to Kiosk, i'd like to check if a Kiosk object is part of the relationship. I could do self.apps.get(id=app_id).exists() and check if True or self.apps.get(id=app_id) and catch the ObjectDoesNotExist error or self.apps.filter(id=app_id)… >>> More