Problem in Hibernate mapping

ajith_raj · **Joined:** Wed Jun 17, 2009 2:04 am **Posts:** 6

Hi all

My domain is like this :

Code:

 class lines{  
     String comment;  
     Collection parent; (of type lines)  
     Collection children; (of type lines)  
 }  

I have two tables to which this is to be saved...

Code:

 lines  
 {  
    id serial NOT NULL,  
   comments character varying(500),  
 }  
   
 lines_hierarchy  
 (  
   id serial NOT NULL,  
   parent_id integer NOT NULL,  
   child_id integer NOT NULL  
 }  

Please help me to write an hibernate mapping for this

pb00067 · **Joined:** Tue Jun 16, 2009 3:36 am **Posts:** 990

I would try with following:

@Entity
@org.hibernate.annotations.Table( appliesTo = "lines")
@SecondaryTable(name = "lines_hierarchy")
class Lines {
@Id @GeneratedValue
private long id;

@Column
String comment;

@javax.persistence.ManyToMany
protected Set<Lines> parent = new java.util.HashSet<Lines>();

@javax.persistence.ManyToMany(mappedBy = "parent")
protected Set<Lines> children = new java.util.HashSet<Lines>();
}

N.B.: I not understand for what purpose lines_hierarchy.id stands for.

ajith_raj · **Joined:** Wed Jun 17, 2009 2:04 am **Posts:** 6

Sorry to say that I don't understand annotations...

and you specified about using HashSet..??? why?? cant i use Collection..

thanks....

pb00067 · **Joined:** Tue Jun 16, 2009 3:36 am **Posts:** 990

Quote:

Sorry to say that I don't understand annotations...

Since ever I work only with annotations, and I have not the time to translate it for you into hbm syntax.

Collection is just an interface. For concrete use you need to specify a concrete implementation of collection and
HashSet is an implementation of collection (overmore Set is the suggested first-choice by hiberante)

Cameron McKenzie · **Posted:** Wed Feb 10, 2010 8:45 am

The mappings provided look good. You should get comfortable with them.

Here's a little tutorial on using Hibernate Many to Many mappings. Give it a look, along with the section on setting up Hiberante with annotations support:

http://www.hiberbook.com/HiberBookWeb/l ... ationships