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One to Many relationship with secondary table

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soysus

Post subject: One to Many relationship with secondary table

Posted: Wed Jul 28, 2010 9:07 am

Newbie

Joined: Wed Jul 28, 2010 8:54 am
Posts: 3

Hi,

I'm sorry if my question is stupid, I am a bit new on this. I am searching for a solution on this for some time but I didn't find anything.

I have a database to save Articles that are tagged

I have the following tables (reduced to clarify the problem)

------
Article|
------
art_id |
title |
... |
------

----------
Tag |
----------
tag_name |
----------

----------------
Article_has_Tag |
----------------
art_id |
tag_name |
----------------

And I want to map this into 2 entities

Code:

@Entity
public class Tag implements Serializable{
   
   @Id
   private String name;

   //getters and setters..
}

Code:

@Entity
@SecondaryTables({
    @SecondaryTable(name="Article_has_Tag", pkJoinColumns={
             @PrimaryKeyJoinColumn(name="id", referencedColumnName="art_id")})
    })
public class Article implements IClusterable{
   
   @Id
   @GeneratedValue
   @Column(name = "art_id", nullable = false)
   private int id;   
   private String title;

   @OneToMany 
        @JoinColumn(name="tag_name", referencedColumnName="tag_name",
                table="Article_has_Tag")
   private List<String> tags;

   //getters and setters..
}

but I am not able to map it... this is my last try... and I got
org.hibernate.cfg.NotYetImplementedException: Collections having FK in secondary table

some help?

Thanks

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soysus

Post subject: Re: One to Many relationship with secondary table

Posted: Wed Jul 28, 2010 9:53 am

Newbie

Joined: Wed Jul 28, 2010 8:54 am
Posts: 3

I don't understand it completely but I found a solution that, at least, compiles

Code:

@Entity
public class Article implements IClusterable{
   
   @Id
   @GeneratedValue
   @Column(name = "art_id", nullable = false)
   private int id;   
   private String title;

   @ManyToMany(cascade=CascadeType.PERSIST)
        @JoinTable(name="article_has_tag",
           joinColumns=@JoinColumn(name="art_id", referencedColumnName="art_id"),
           inverseJoinColumns=@JoinColumn(name="tag_name", referencedColumnName="name"))
   private List<Tag> tags;

  //...
}

http://openjpa.apache.org/builds/1.0.2/ ... field.html

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icojo

Post subject: Re: One to Many relationship with secondary table

Posted: Tue Dec 21, 2010 7:09 am

Newbie

Joined: Tue Dec 21, 2010 7:03 am
Posts: 1

If you make it a bidirectional relation and use the mapedBy attribute, it may work.
It solved the problem for me

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