Hi,
Is it necessaryto have one HBM.XML file for each class. In my DB design there are a lot of One-to-One relationship. So is there any way Can i have one class Mapped to Different Tables.....
If yes Can anyone give me a small examle how will the HBM.XML file look like

Thankz

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Can you explain a bit more as to what you want to achieve.

I do not think you can map a class to more than one table using NHibernate (I may be wrong as I too am a new user). One way to do this would be to define a view first and then map the view.

I'm guessing you may need joined-subclass

http://www.hibernate.org/hib_docs/reference/en/html/mapping.html#mapping-declaration-joinedsubclass

if not, what you need is to clarify your question ;) ....

Let me explain my Problem more in detail: Assuming we hav 2 Tables with a One to One Mapping

Table Name: Customer_Details.
Customer_id(PK)
Customer_name

2nd table: Customer Address
Customer_id(PK+FK)
Customer_address

Now i want a class Customer as

Class Customer
{
string Customer_id;
string Customer_name;
string Customer_address
}

Now is there a way This can be implemented. ????

Regards

Prasanth

As far I know , the only way to use one mapping with severall classes is to use component mapping - but it requires to have all columns in one table (see the docs)

In my opinion , for your case it is the best to implement addional class for the address and map it as ordinary one-to-one with id generator set as "foreign":

Class Customer
{
string Customer_id;
string Customer_name;
Address Customer_address
}

Class Address
{
string the_address
}

here is doc about one-to-one (look for generator class="foreign" phase) : http://www.hibernate.org/hib_docs/reference/en/html/mapping.html#mapping-declaration-onetoone


And finally - if you don't like many hbm.xml files (each for every class) - why not to put some <class> elements in one <hibernate-mapping> :) ? (not recommended approach btw)

The feature you are after is available in Hibernate 3 and has not yet been ported to NHibernate. It uses the <join> element in the class mapping file.

The best way to achieve this with NHibernate as it currently stands is using the joined-subclass mapping. Create a CustomerBase class (abstract) which maps to the Customer table, and then your Customer class inherits from CustomerBase adding the Address property, and is mapped using joined-subclass.

Thankz.....

I've submited a request for this:
http://jira.nhibernate.org/browse/NH-466...
Vote for it in Jira if you need it