Hi,

An application that I'm working on has a Person class that consists of a Location class that contains a Country class.
These objects are read from a feed every day before inserting into or updating the database.
Primary keys will be generated automatically by Hibernate.

Say I have a Country class with attributes as follows:
countryID (Primary Key, not included in feed)
countryCode (Unique, included in feed)
countryDesc (Text, included in feed)

If I'm inserting Person objects which in turn contains Country objects, and a Country's countryDesc changes, will Hibernate go and insert a new Country object?
The problem I have is that the feed won't contain the Primary Key, but will Hibernate be able to figure out that it should update the existing Country instead of adding a new one?

Hope this makes sense. Thanks.

Sorry to bump this, but does anyone have any ideas please?

Thanks in advance.

If the Country object doesn't have the countryID populated, when you call Save, Hibernate should try to populate it based on the generator defined.

See section 5.1.4.6 in
http://www.hibernate.org/hib_docs/refer ... pping.html

If you can let the database assign countryID, countryCode may be used as the natural key.

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Please rate

If I insert a Country object that contains only a code "USA" and description "United States"
it inserts a new row as follows:
1 - USA - United States, where 1 is the auto-generated PK

If I attempt to add a new Country object again only with code "USA" and description "United States of America" it throws a constraint violation exception from the database as it attempts to add a new Country object.

Is there any way at all that Hibernate will realize that the second Country object already exists based on it's natural ID and will update the existing row as opposed to attempting to insert a new one?

As I'd prefer to generate the PKs using Hibernate.

Thanks again.

You'll have to write your own code for checking that. For example, something like this:

I think in hibernate you can define the custom PrimaryKey class for an entity.

Ex.
@Entity
@Table(name = "Person")
@IdClass(PersonPK.class)
public class Person {
.......

}

public class PersonPK{

// Here u can mention your custom primary key fields for the entity.
}