Java 如何在hibernate中查询地图元素?
我有一个hibernate映射,如下所示:Java 如何在hibernate中查询地图元素?,java,hibernate,criteria,Java,Hibernate,Criteria,我有一个hibernate映射,如下所示: <hibernate-mapping> <class name="MutableEvent" table="events" mutable="true" dynamic-insert="true" dynamic-update="true"> <id name="id"> <generator class="assigned" />
<hibernate-mapping>
<class name="MutableEvent" table="events"
mutable="true" dynamic-insert="true" dynamic-update="true">
<id name="id">
<generator class="assigned" />
</id>
<property name="sourceTimestamp" />
<property name="entryTimestamp" />
<map name="attributes" table="event_attribs"
access="field" cascade="all">
<key column="id" />
<map-key type="string" column="key" />
<element type="VariantHibernateType">
<column name="value_type" not-null="false" />
<column name="value_string" not-null="false" />
<column name="value_integer" not-null="false" />
<column name="value_double" not-null="false" />
</element>
</map>
</class>
</hibernate-mapping>
...
private static final String[] PROPERTY_NAMES = { "type", "string", "integer", "double" };
public String[] getPropertyNames() {
return PROPERTY_NAMES;
}
...
重要的是,此操作失败,出现“无法解析属性:attributes.other”:
这个问题有解决办法吗
更新
List l = find("from MutableEvent M where M.attributes['other'] = ?", new Variant("aValue"));
上面的代码没有抛出异常,但查询本身仍然不是我想要的。我创建了一个自定义类型,正如映射所示,实际上我希望查询一个字符串(column value_string),但是任何修改查询以访问该类型的一部分的尝试,如“from MutableEvent M where M.attributes['other'].string=?”都不起作用。那么如何查询组件的一部分呢
该类型的实现方式如下:
<hibernate-mapping>
<class name="MutableEvent" table="events"
mutable="true" dynamic-insert="true" dynamic-update="true">
<id name="id">
<generator class="assigned" />
</id>
<property name="sourceTimestamp" />
<property name="entryTimestamp" />
<map name="attributes" table="event_attribs"
access="field" cascade="all">
<key column="id" />
<map-key type="string" column="key" />
<element type="VariantHibernateType">
<column name="value_type" not-null="false" />
<column name="value_string" not-null="false" />
<column name="value_integer" not-null="false" />
<column name="value_double" not-null="false" />
</element>
</map>
</class>
</hibernate-mapping>
...
private static final String[] PROPERTY_NAMES = { "type", "string", "integer", "double" };
public String[] getPropertyNames() {
return PROPERTY_NAMES;
}
...
尝试为条件创建别名
criteria.createAlias( "attributes", "as" );
criteria.add( Restrictions.ilike( "as.other", new Variant("aValue") );
CriteriaAPI不如HQL强大,您可以在HQL中查询映射。