Hi,
I have a problem mapping a legacy database. In the database is a construction to force a maps to construction

The class model


Class A has a many-to-many relation with class C
Class A has a one-to-many relation with class B
Class C has a one-to-many relation with class D
Class D maps to class B

Database


Table V is the many-to-many table between table A and table C
Table B has a table_a_id for the on-to-many reference
Table V has a generated id(?), table_a_id and table_c_id
Table D has a table_v_id reference

First I tried to map the class model straight forward with some sql commands for the fetch and a stored procedure to save but I got some problems with the way hibernate writes the data; it first writes the properties (the one-to-many) and then the sets (the many-to-many) and that is not allowed because the database enforces the maps to constraint.

the idea I had then was to create a 'virtual' ClassV the will be created dynamically allowing the class model to stay intact with the many to many relation between A and C. the consequence is that the class model for hibernate looks like this


Class A has a one-to-many relation with class V
Class C has a one-to-many relation with class V
Class A has a one-to-many relation with class B
Class V has a one-to-many relation with class D

when I try this I get the error

NHibernate.MappingException: Foreign key in table D must have same number of columns as referenced primary key in table V

this is kind of logical because table A and table C map to table V and hibernate obviously concludes that the references to tables A and C will be the primary key. But in reality table V has another generated id as the primary key. Argh.

Is it possible to map something like this with hibernate and what would be the best approach?

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Hibernate version:
1.2.0
Mapping documents:

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

Full stack trace of any exception that occurs:
2008-04-16 10:21:19,078 [10] ERROR NHibernate.Cfg.Configuration [(null)] - NHibernate.MappingException: Foreign key in table D must have same number of columns as referenced primary key in table V
at NHibernate.Mapping.ForeignKey.set_ReferencedTable(Table value) in C:\backup oude laptop\dev\nhibernate\NHibernate-1.2.0.GA-src\src\NHibernate\Mapping\ForeignKey.cs:line 69
at NHibernate.Cfg.Configuration.SecondPassCompileForeignKeys(Table table, ISet done) in C:\backup oude laptop\dev\nhibernate\NHibernate-1.2.0.GA-src\src\NHibernate\Cfg\Configuration.cs:line 1023
Name and version of the database you are using:
Oracle 10G 2
The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:


Problems with Session and transaction handling?

Read this: http://hibernate.org/42.html[quote][/quote]

I solved it by changing the database.
thanks for reading

I solved it by changing the database.
thanks for reading