Question

I have table1 and table2 that have the same schema… and I want to have only one entity rather than two ( since the fields will be the same).
How would I achieve that in hibernate with XML mapping.
So my goal is when I m querying in the DAO, how would it know which table to pull from if both tables are mapped to the same entity.

I m trying to Not create a parent class and then two subclasses.

Thanks

Answer 1

Sorry for the late answer. i have answered this question several times on stackoverflow.

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To map two identical tables onto one entity class, you need to use the entity-name property of Hibernate or NHibernate.

Documentation is here:
http://docs.jboss.org/hibernate/core/3.2/reference/en/html/mapping.html#mapping-entityname

For example, to map a single class Order to Order and OrderHistory tables, you create a mapping file that maps the order class to the two tables using new entity-names (Order and OrderHistory) like this:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
   <class name="DomainModel.Order, DomainModel"
   table="Orders" entity-name="Order">`  
     <id name="_id" access="field" column="OrderId">
         <generator class="assigned"/>
     </id>
    <property name= ...>
</class>
<class name="DomainModel.Order, DomainModel"
 table="OrderHistories" entity-name="OrderHistory">
     <id name="_id" access="field" column="OrderId">
        <generator class="assigned"/>
     </id>
    <property name= ...>
</class>
</hibernate-mapping>

Then depending on the type of entity you need, you simply call the appropriate Session methods as:

_session.Save("Order", myOrder) 

or

_session.Save("OrderHistory", myOrder)

Simple, isn’t ?

In general entity-name must replace class name in all Hibernate calls.