I have a Menu class that keeps a collection of SalesLineItem objects.
Basically the Menu is a food menu, such as a pizza menu, and the
items such as Coke or Margeritha Pizza are SalesLineItem objects.
The menu lists all the SalesLineItem's it has, depending on what menu the
user chooses.
It may be an Italian food menu or chinese food menu.
This makes the relationship between the Menu class and the SalesLineItem
class a many-to-many relationship.
Also note that the SalesLineItem objects stored in a menu all
have properties such as name, itemcode, price and quantity.

Now, when the user of the system creates a sale, the application creates
a Sale object which also has a many-to-many relationship with the
SalesLineItem class.

First the application retrieves the correct menu, say for example, the
Italian menu.
Then, given an item code we can retrieve an item from the menu and add
it to the sale.

SalesLineItem sli = (SalesLineItem)menu.getSaleslineitems().get(code);
Sale sale = new Sale();
sale.getSaleslineitems().put(sli.getCode(),sli);

This all works fine and is persisted.
But if I increase the quantity, or make any changes dynamically to
a SalesLineItem object after retrieving it from the menu and put it in the
Sale object, these changes happens to any object that keeps a reference
to the changing object.

For example I retrieve a SalesLineItem object such as a Coke from the
Menu class.
I increase the quantity of the Coke , because the customer wants two
cokes for his order, and then add the Coke to a new Sale object.
Now the Coke has a quantity of 2 in the menu, in the new sale
and as well as in other sales that has a coke.
That is the problem, what is the solution?, misuse of hibernate or
must find workarounds for this problem.
Thanks!

See my mapping file here below , if you can spot any errors please!

Hi Sinoea,

Your problem isn't with Hibernate, or many-to-one, or your mapping. It's with your object model!

You need a MenuItem class. Right now you are trying to make your SaleLineItem class also function as a MenuItem. That'll never work, for the reasons you are experiencing!

Here's what you want...

A Menu has a Set (many-to-many) of MenuItems.

A MenuItem has properties: name, price etc. (but note: not[i] qty or total!)

A Sale has a Set (one-to-many) of SaleLineItems.

A SaleLineItem has:
• a menuItem property (many-to-one to MenuItem)
• some value-type properties: qty, subtotal

Does that clear things up?
—ml—

Billion trillion thanks, it works fantastic now!