java - Hibernate 与 createCriteria 和 createAlias 的关联

Question

我有两个简单的映射:

<class name="org.testing.Person" table="PERSON">
        <id name="personId" type="long" column="PERSON_ID">
            <generator class="native"/>
        </id>
        <property name="personName" type="string" not-null="true" column="PERSON_NAME"/>
        <many-to-one name="personAddress" class="org.testing.Address" column="PERSON_ADDRESS"    not-null="true" cascade="all" unique="true"/>
</class>

和

<class name="org.testing.Address" table="ADDRESS">
    <id name="addressId" type="long" column="ADDRESS_ID">
        <generator class="native" />
    </id>
    <property name="street" column="ADDRESS_STREET" type="string" />
    <property name="city" column="ADDRESS_CITY" type="string" />
    <property name="state" column="ADDRESS_STATE" type="string" />
</class>

我尝试像这样获取个人地址的属性:

session.createCriteria(Person.class)
                    .add(Restrictions.eq("personName", "Frodo"))
                    .createAlias("personAddress", "pa")
                    .setProjection(Projections.property("pa.street"))
                    .list();

并且有效。比这样:

session.createCriteria(Person.class)
                    .add(Restrictions.eq("personName", "Frodo"))
                    .createCriteria("personAddress")
                    .setProjection(Projections.property("street"))
                    .list();

它抛出:org.hibernate.QueryException:无法解析属性:街道:org.testing.Person。我认为两者应该给出相同的结果。我哪里错了？提前致谢!

Answer 1

.setProjection(Projections.property("street")) 始终对根条件进行操作。要投影连接的项目，您必须使用您发布的第一个版本。