16.2.1. 使用return-property来明确地指定字段/别名

使用<return-property>你可以明确的告诉Hibernate使用哪些字段别名,这取代了使用{}-语法 来让Hibernate注入它自己的别名.

<sql-query name="mySqlQuery">
    <return alias="person" class="eg.Person">
      <return-property name="name" column="myName"/>
      <return-property name="age" column="myAge"/>
      <return-property name="sex" column="mySex"/>
    </return>
    SELECT person.NAME AS myName,
           person.AGE AS myAge,
           person.SEX AS mySex,
    FROM PERSON person WHERE person.NAME LIKE :name
</sql-query>

<return-property>也可用于多个字段,它解决了使用{}-语法不能细粒度控制多个字段的限制

<sql-query name="organizationCurrentEmployments">
            <return alias="emp" class="Employment">            
             <return-property name="salary"> 
               <return-column name="VALUE"/>
               <return-column name="CURRENCY"/>            
             </return-property>
             <return-property name="endDate" column="myEndDate"/>
            </return>
            SELECT EMPLOYEE AS {emp.employee}, EMPLOYER AS {emp.employer}, 
            STARTDATE AS {emp.startDate}, ENDDATE AS {emp.endDate},
            REGIONCODE as {emp.regionCode}, EID AS {emp.id}, VALUE, CURRENCY
            FROM EMPLOYMENT
            WHERE EMPLOYER = :id AND ENDDATE IS NULL
            ORDER BY STARTDATE ASC
</sql-query>

注意在这个例子中,我们使用了<return-property>结合{}的注入语法. 允许用户来选择如何引用字段以及属性.

如果你映射一个识别器(discriminator),你必须使用<return-discriminator> 来指定识别器字段