Need help with one to one mapping

Christian Gmeiner · **Joined:** Sun May 07, 2006 7:40 pm **Posts:** 3

Hibernate version:
3.x

Mapping documents:

Bus.hbm.xml:

Code:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 05.05.2006 11:23:58 by Hibernate Tools 3.1.0.beta5 -->
<hibernate-mapping>
    <class name="database.BusData" table="bus" catalog="busmaster">
        <comment></comment>
        <id name="busId" type="int">
            <column name="bus_id" />
            <generator class="native" />
        </id>
        <property name="internalId" type="string">
            <column name="internal_id" length="20" not-null="true">
                <comment></comment>
            </column>
        </property>
        <property name="seats" type="short">
            <column name="seats" not-null="true">
                <comment></comment>
            </column>
        </property>
        <property name="standingrooms" type="short">
            <column name="standingrooms" not-null="true">
                <comment></comment>
            </column>
        </property>
        <property name="licenceplate" type="string">
            <column name="licenceplate" length="20">
                <comment></comment>
            </column>
        </property>
        <property name="technical" type="string">
            <column name="technical" length="65535">
                <comment></comment>
            </column>
        </property>
        <property name="buscategoryId" type="int">
            <column name="buscategory_id" not-null="true">
                <comment></comment>
            </column>
        </property>
        <property name="internalbus" type="boolean">
            <column name="internalbus" not-null="true">
                <comment></comment>
            </column>
        </property>
        <property name="deleted" type="boolean">
            <column name="deleted" not-null="true">
                <comment></comment>
            </column>
        </property>
    </class>
</hibernate-mapping>

Buscategory.hbm.xml

Code:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 05.05.2006 11:23:58 by Hibernate Tools 3.1.0.beta5 -->
<hibernate-mapping>
    <class name="database.BuscategoryData" table="buscategory" catalog="busmaster">
        <comment></comment>
        <id name="buscategoryId" type="int">
            <column name="buscategory_id" />
            <generator class="native" />
        </id>
        <property name="categoryname" type="string">
            <column name="categoryname" length="100" not-null="true">
                <comment></comment>
            </column>
        </property>
    </class>
</hibernate-mapping>

DB: http://x-factor.dyndns.org/~austriancod ... 0agent.png

As you can see on the picture, the table bus has a foreign key to buscategory. It sounds maybe silly, but at the moment i have no idea how to add this to the mapping files :(
I have read the docs, but i can't under stand it.

Thanks,
Christian

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

That's a many to one mapping, not one to one. Two different buses might have the same buscategory. Many buses to one category.

Add this to your bus mapping:

Code:

<many-to-one name="Category" class="database.BuscategoryData" not-null="true"/>

I'm assuming that every bus has one and only one category. Remove the not-null if bues may have null categories (i.e. zero or one categories).

Christian Gmeiner · **Joined:** Sun May 07, 2006 7:40 pm **Posts:** 3

Thanks.. works very well :)

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

You're welcome. Don't forget to rate.