I have the follwing entities

1. Category
2. Sub- Category
3. Product
4. Attributes
5. Item

Category may contain zero or many sub-cats.
Sub-category may contain zero or more products.
Product have the many to many relation with Attributes.
and Product may contain the zero or many items.

Here the problem comes. Here the Item is like an instance of the Product.so it contains the values of the product attributes.

I have created tables Product , Attribute and Product_Attribute. Now when it comes to Item i am not able to proceed.(how to map)

I think hibernate users will help me in this.

Thanks in advance.

Rao.

Hibernate version: 2.1

Mapping documents:

Code between sessionFactory.openSession() and session.close():

Full stack trace of any exception that occurs:

Name and version of the database you are using:

The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:

If I understood you well, your Item is in fact a Product. So it means that a Product contain a one-to-many relationship to a set of productS, if only a Item-Product can only be part of ONLY ONE Product. In this case you only have to add an extra column inside Product telling wich Item-Product is is the child a a Parent-Product : "itemForeignKeyId" (pointing on ProductId).

In the other case, if an Item-Product can be part of many Products at the same time, you need to have a many-to-many relationship (and a database table item-product linking all Item-Product to a Product bu the ProductId key).

Lets check the simpler case:

You just have to create a Set (or any collection) of "items" in you Product class. This Set will be linked to a set of "itself"... Products.

in the java code:



Inside the Product mapping xml add :



You can also make the inverse relationship many-to-one inside Product to another Product.




This seems to me the easiest way.

For some transparency, you could also make a class Items heriting of Product and adding the Set of Items, and the getter/setter associated to it.

I also see that you subCategory could also be a Category pointing to itself... you could do the same pattern there also.

Hope it helped.

Etienne
Montreal

Here some corrections.



and not Set item = new HashSet();




and not

<many-to-one name="ParentProduct" class="Product">
<column name="itemForeignKeyId" not-null="false" />
</many-to-one>

and add this field:



inside your Product class.

Dont forget the equals() and hashCode() function for all your classes, and the addItem(Product item); in the Product class if you want to add a item to a Product...

Etienne.

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