How to define a SELF REFERENCE using Annotations

marcelojuventino · **Posted:** Wed Apr 19, 2006 10:40 am

Hello guys!

I'm a beginner with Hibernate Annotations and I would like to know how to create a self reference in an entity. For example: I have a class called CATEGORY that can contains SUB CATEGORIES. I would like to obtain these SUB CATEGORIES and, through a category obtain the SUPER CATEGORY. Something like:

Code:

class Category
{

  // Category Attributes

  public ArrayList<Category> getSubCategories()
  {

  }

  public Category getSuperCategory()
  {

  }

}

alesj · **Posted:** Thu Apr 20, 2006 3:17 am

Code:

class Category
{

  // Category Attributes

  @OneToMany
  @JoinColumn(name = "category_id", unique = false, nullable = true, insertable = true, updatable = true)
  public [b]List[/b]<Category> getSubCategories()
  {

  }


  @ManyToOne
  @JoinColumn(name = "category_id", unique = false, nullable = true, insertable = true, updatable = true)
  public Category getSuperCategory()
  {

  }

}

Be aware of List interface!

marcelojuventino · **Posted:** Thu Apr 20, 2006 8:27 am

Hello Alesj!!!

Thanks for your reply!!!

How I will define my ID and other attributes? There's some difference in declaration to support this kind of relationship?

alesj · **Posted:** Thu Apr 20, 2006 8:46 am

http://hibernate.org/5.html

marcelojuventino · **Posted:** Thu Apr 20, 2006 9:09 am

I already read the annotations documentation but it doesn't explain how to define this kind of relationship and there aren't so much sources showing how to do it using EJB 3.

alesj · **Posted:** Thu Apr 20, 2006 9:28 am

marcelojuventino wrote:

How I will define my ID and other attributes?

Quote:

but it doesn't explain how to define this kind of relationship

Sure ...

emmanuel · **Posted:** Thu Apr 27, 2006 9:40 am

Actually more something like that

Code:

class Category
{

  // Category Attributes

  @OneToMany(mappedBy="superCategory")
  public [b]Set[/b]<Category> getSubCategories()
  {

  }


  @ManyToOne
  @JoinColumn(name = "category_id")
  public Category getSuperCategory()
  {

  }

}