Question

hql = "select rm.* from remoteunit rm inner join mo m on rm.MOID = m.ID left join     
orgmomapping o on rm.MOID = o.MOID join organization org on org.ID = o.ORGANIZATIONID 
where m.DOMAINID = :id";

query = session.createSQLQuery(hql);

此查询在使用

查询时返回对象列表

remoteUnitList = (ArrayList<RemoteUnitDetails>)query.list();

但是当我试图获得一个对象时

RemoteUnitDetails details = (RemoteUnitDetails)remoteUnitsList.get(i);

我得到了类强制转换异常。

我使用的是MySQL数据库。在hibernate中使用条件时，我无法匹配orgmomapping和remoteunit表。因为

orgmomapping -> id, organizationId, remoteUnitId
remoteunit   -> id

此远程单位ID可能在orgmomapping中存在，也可能不存在。

请提出解决方案

由于

更新

RemoteUnitDetails.hbm.xml

<hibernate-mapping>
<class name="---.RemoteUnitDetails" table="remoteunit"
    lazy="false">
    <id name="id" column="ID">
        <generator class="increment" />
    </id>
    <many-to-one name="remoteUnit" column="MOID"
        class="---.RemoteUnit" not-null="true"></many-to-one>
    <property name="address" column="ADDRESS" />
    <property name="postalCode" column="POSTALCODE" />
    <property name="city" column="CITY" />
    <property name="region" column="REGION" />
    <property name="visible" column="VISIBLE" />
    <property name="lowPowerMode" column="LOWPOWERMODE" />
    <property name="wakeUpInterval" column="WAKEUPINTERVAL" />
    <property name="awakeInterval" column="AWAKEINTERVAL" />
    <property name="resetAtNextInterval" column="RESETATNEXTINTERVAL" />
    <property name="logInterval" column="LOGINTERVAL" />
    <property name="sendIntervalLogData" column="SENDINTERVALLOGDATA" />
    <property name="sendIntervalAttr1" column="SENDINTERVALATTR1" />
    <property name="sendIntervalAttr2" column="SENDINTERVALATTR2" />

  </class>
</hibernate-mapping>

RemoteUnit.hbm.xml

 <hibernate-mapping>
<class name="---.RemoteUnit" table="mo" lazy="false">
    <id name="id" column="ID">
        <generator class="increment" />
    </id>

    <property name="name" />
    <property name="aliasName" column="SCREENNAME" />
    <property name="description" column="DESCRIPTION" />
    <property name="isActive" column="ISLIVE" />

    <many-to-one name="domain" column="DOMAINID"
        class="---.Domain" not-null="true" />
    <!-- Foreign key -->
    <many-to-one name="moType" column="MOTYPEID"
        class="---.MoType" not-null="true" />
</class>
 </hibernate-mapping>

OrgMoMapping.hbm.xml

<hibernate-mapping>
<class name="---.OrgRemoteUnitMapping" table="orgmomapping"
    lazy="false">
    <id name="id" column="ID">
        <generator class="identity" />
    </id>

    <many-to-one name="organization" column="ORGANIZATIONID"
        class="---.Organization" not-null="true"></many-to-one>
    <many-to-one name="remoteUnit" column="MOID"
        class="---.RemoteUnit" not-null="true"></many-to-one>
</class>
</hibernate-mapping>

Answer 1

我不建议您为此目的使用本机SQL，因为您可以使用条件API轻松实现此目的。你可以做这样的事情。它可能对你有帮助。

ProjectionList projections = Projections.projectionList();
projections.add(Projections.property("column.columnName"), "columnName");

Criteria criteria = getCurrentSession().createCriteria(<<remoteunit>>.class, "remoteunit");
criteria.createAlias("remoteunit.<<remoteunit_to_mo_joinfield>>", "mo", JoinType.INNER_JOIN);
criteria.createAlias("mo.<<mo_to_orgmomapping_join_field>>", "orgmomapping", JoinType.LEFT_OUTER_JOIN);
criteria.setProjection(projections);
criteria.setResultTransformer(Criteria.ALIAS_TO_ENTITY_MAP);
List<Map<String,? extends Object>> list = criteria.list();

使用hibernate时获取类转换异常

1 个答案: