24.4. 杂例

这些例子全部来自于 Hibernate 的 test suite，同时你也可以找到其他有用的例子。可以参考 Hibernate 的 test 目录。

24.4.1. "Typed" 一对一关联

<class name="Person">
    <id name="name"/>
    <one-to-one name="address" 
            cascade="all">
        <formula
>name</formula>
        <formula
>'HOME'</formula>
    </one-to-one>
    <one-to-one name="mailingAddress" 
            cascade="all">
        <formula
>name</formula>
        <formula
>'MAILING'</formula>
    </one-to-one>
</class>

<class name="Address" batch-size="2" 
        check="addressType in ('MAILING', 'HOME', 'BUSINESS')">
    <composite-id>
        <key-many-to-one name="person" column="personName"/>
        <key-property name="type" column="addressType"/>
    </composite-id>
    <property name="street" type="text"/>
    <property name="state"/>
    <property name="zip"/>
</class
>

24.4.2. 组合键示例

<class name="Customer">

    <id name="customerId"
        length="10">
        <generator class="assigned"/>
    </id>

    <property name="name" not-null="true" length="100"/>
    <property name="address" not-null="true" length="200"/>

    <list name="orders"
            inverse="true"
            cascade="save-update">
        <key column="customerId"/>
        <index column="orderNumber"/>
        <one-to-many class="Order"/>
    </list>

</class>

<class name="Order" table="CustomerOrder" lazy="true">
    <synchronize table="LineItem"/>
    <synchronize table="Product"/>
    
    <composite-id name="id" 
            class="Order$Id">
        <key-property name="customerId" length="10"/>
        <key-property name="orderNumber"/>
    </composite-id>
    
    <property name="orderDate" 
            type="calendar_date"
            not-null="true"/>
    
    <property name="total">
        <formula>
            ( select sum(li.quantity*p.price) 
            from LineItem li, Product p 
            where li.productId = p.productId and li.customerId = customerId and li.orderNumber = orderNumber )
        </formula>
    </property>
    
    <many-to-one name="customer"
            column="customerId"
            insert="false"
            update="false" 
            not-null="true"/>
        
    <bag name="lineItems"
            fetch="join" 
            inverse="true"
            cascade="save-update">
        <key>
            <column name="customerId"/>
            <column name="orderNumber"/>
        </key>
        <one-to-many class="LineItem"/>
    </bag>
    
</class>
    
<class name="LineItem">
    
    <composite-id name="id" 
            class="LineItem$Id">
        <key-property name="customerId" length="10"/>
        <key-property name="orderNumber"/>
        <key-property name="productId" length="10"/>
    </composite-id>
    
    <property name="quantity"/>
    
    <many-to-one name="order"
            insert="false"
            update="false" 
            not-null="true">
        <column name="customerId"/>
        <column name="orderNumber"/>
    </many-to-one>
    
    <many-to-one name="product"
            insert="false"
            update="false" 
            not-null="true"
            column="productId"/>
        
</class>

<class name="Product">
    <synchronize table="LineItem"/>

    <id name="productId"
        length="10">
        <generator class="assigned"/>
    </id>
    
    <property name="description" 
        not-null="true" 
        length="200"/>
    <property name="price" length="3"/>
    <property name="numberAvailable"/>
    
    <property name="numberOrdered">
        <formula>
            ( select sum(li.quantity) 
            from LineItem li 
            where li.productId = productId )
        </formula>
    </property>
    
</class
>

24.4.3. 共有组合键属性的多对多（Many-to-many with shared composite key attribute）

<class name="User" table="`User`">
    <composite-id>
        <key-property name="name"/>
        <key-property name="org"/>
    </composite-id>
    <set name="groups" table="UserGroup">
        <key>
            <column name="userName"/>
            <column name="org"/>
        </key>
        <many-to-many class="Group">
            <column name="groupName"/>
            <formula
>org</formula>
        </many-to-many>
    </set>
</class>
    
<class name="Group" table="`Group`">
    <composite-id>
        <key-property name="name"/>
        <key-property name="org"/>
    </composite-id>
    <property name="description"/>
    <set name="users" table="UserGroup" inverse="true">
        <key>
            <column name="groupName"/>
            <column name="org"/>
        </key>
        <many-to-many class="User">
            <column name="userName"/>
            <formula
>org</formula>
        </many-to-many>
    </set>
</class>

24.4.4. 基于内容的识别

<class name="Person"
    discriminator-value="P">
    
    <id name="id" 
        column="person_id" 
        unsaved-value="0">
        <generator class="native"/>
    </id>
    
            
    <discriminator 
        type="character">
        <formula>
            case when title is not null then 'E' when salesperson is not null then 'C' else 'P' 
            end
        </formula>
    </discriminator>

    <property name="name" 
        not-null="true"
        length="80"/>
        
    <property name="sex" 
        not-null="true"
        update="false"/>
    
    <component name="address">
        <property name="address"/>
        <property name="zip"/>
        <property name="country"/>
    </component>
    
    <subclass name="Employee" 
        discriminator-value="E">
            <property name="title"length="20"/>
            <property name="salary"/>
            <many-to-one name="manager"/>
    </subclass>
    
    <subclass name="Customer" 
        discriminator-value="C">
            <property name="comments"/>
            <many-to-one name="salesperson"/>
    </subclass>
    
</class
>

24.4.5. 备用键的联合

<class name="Person">
    
    <id name="id">
        <generator class="hilo"/>
    </id>
    
    <property name="name" length="100"/>
    
    <one-to-one name="address" 
        property-ref="person"
        cascade="all"
        fetch="join"/>
    
    <set name="accounts" 
        inverse="true">
        <key column="userId"
            property-ref="userId"/>
        <one-to-many class="Account"/>
    </set>
    
    <property name="userId" length="8"/>

</class>

<class name="Address">

    <id name="id">
        <generator class="hilo"/>
    </id>

    <property name="address" length="300"/>
    <property name="zip" length="5"/>
    <property name="country" length="25"/>
    <many-to-one name="person" unique="true" not-null="true"/>

</class>

<class name="Account">
    <id name="accountId" length="32">
        <generator class="uuid"/>
    </id>
    
    <many-to-one name="user"
        column="userId"
        property-ref="userId"/>
    
    <property name="type" not-null="true"/>
    
</class
>