Hi

I have a many-to-many (bidirectional) relationship working. I now want to add an extra field to the join table and let one of the sides populate with this field. Is this possible?

For example

A (mapped to table A) has a collection of Bs. B (mapped to table B) has a collection of As. Can each A instance here fetch a field from the join table (A_B) and set this in a property in the A object?

I know I can map the join table to an object and make two seperate 1:N relationships and thereby access the field, but I do not want an entirely new object, mappin etc for just one extra field.

It is not possible to populate one of the tables you mention with the extra property.
What you want to create a class for the join table with the extra property. This class needs a composite key with foreign key references.

Read this blog how to make it happen:

http://java-aap.blogspot.com/2006/04/hibernate-annoations-composite-primary.html#links

Thanks.

By the way I really want to create the extra object as this helps preserve the many-to-many relationship. Populating one side with the value will give me a 1:N on that value and not a N:M..