The difference is that I don't have a many to many relationship. A "B"
entities can have only one "A" object

On Jan 27, 5:14 pm, Shadowboxer <[email protected]> wrote:
> Hi,
>
> I have something similar in my web app. I did it like this:
>
> Class A mapping:
>
> <?xml version="1.0" encoding="utf-8" ?>
> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
>   <class name="A" table="table_A" >
>
>     <id name="Code" type="Int32" >
>       <column name="id" sql-type="integer" not-null="true"
> unique="true" />
>       <generator class="identity" />
>     </id>
>     <property name="Name" type="String">
>       <column name="name" length="100" sql-type="varchar" not-
> null="true" />
>     </property>
>
>    <set name="B" lazy="true" cascade="save-update" table="table_AB">
>       <key column="idA" />
>      <many-to-many class="B"  column="idB"/>
>     </set>
>
> </class>
> </hibernate-mapping>
>
> Class B mapping:
>
> <?xml version="1.0" encoding="utf-8" ?>
> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
>   <class name="B" table="table_B" >
>     <id name="Code" type="Int32">
>       <column name="id" sql-type="integer" not-null="true"
> unique="true" />
>       <generator class="identity" />
>     </id>
>
>     <property name="Name" type="String">
>       <column name="name" length="100" sql-type="varchar" not-
> null="true" />
>     </property>
>
>     <set name="A" lazy="true" cascade="save-update" table="table_AB">
>           <key column="idB"/>
>           <many-to-many class="A" column="idA"/>
>     </set>
>
>   </class>
> </hibernate-mapping>
>
> Hope it helps
>
> On Jan 27, 10:49 am, Dana Efros <[email protected]> wrote:
>
> > Hi. I have to 2 entities:
>
> > class A{
> > int id;
> > string name;}
>
> > class B{
> > int id;
> > A refObj;
> > string name;}
>
> > How can I map this 2 classes so I will have 3 tables:
> > table A with 2 columns: id and name
> > table B with 2 columns: id and name
> > table AB with 2 columns: idA and idB  (idB is unique)
>
> > In the AB table I need to have a row only when refObj will not be
> > null.The field refObj from the B entity will have values only
> > occasionally and I don't want to have a column in the B table with
> > null value for almost all the rows
>
> > With a many to many relations I know how, but with a reference ...
> > Thanks

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