How to mapping inheritance

skr0403 · **Joined:** Fri Jun 24, 2011 6:22 am **Posts:** 3

Hi
i'm begginer in NHibernate, im trying to learn a basic mapping methods and I have a big problem with them.

I mean:
I have two classes

Code:

class Customer : Person{
     public int CustomerId;
     public string FirstName;
}

and

Code:

class Person{
    public int PersonId
    public string LastName;
}

How can I map this inheritance?
I'm trying to:

Code:

<?xml version="1.0"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="APP" auto-import="true">
  <class name="APP.Customer, APP" lazy="false">
    <id name="CustomerId" access="field" type="int">
      <generator class="increment" />
    </id>
    <property name="FirstName" access="field" column="FirstName"/>
    <joined-subclass name="Person">
      <key column="PersonId" />
      <property name="LastName"/>
    </joined-subclass>
  </class>
</hibernate-mapping>

but I have a exception that "could not load a Person type in assemply APP"

I don't know how to do it.
Help me please.

manimoor · **Joined:** Wed Aug 10, 2011 4:45 am **Posts:** 3

Hi..Hibernate supports the three basic inheritance mapping strategies like...

table per class hierarchy

table per subclass

table per concrete class

In addition, Hibernate supports a fourth, slightly different kind of polymorphism:

implicit polymorphism

example:The ordering inside a single mapping file still needs to be defined as superclasses before subclasses.
<hibernate-mapping>
<subclass name="DomesticCat" extends="Cat" discriminator-value="D">
<property name="name" type="string"/>
</subclass>
</hibernate-mapping>

Table per class hierarchy example
<class name="Payment" table="PAYMENT">
<id name="id" type="long" column="PAYMENT_ID">
<generator class="native"/>
</id>
<discriminator column="PAYMENT_TYPE" type="string"/>
<property name="amount" column="AMOUNT"/>
...
<subclass name="CreditCardPayment" discriminator-value="CREDIT">
<property name="creditCardType" column="CCTYPE"/>
...
</subclass>
<subclass name="CashPayment" discriminator-value="CASH">
...
</subclass>
<subclass name="ChequePayment" discriminator-value="CHEQUE">
...
</subclass>
</class>