hibernate不执行快速获取（使用fetch=“join”和lazy=“false”）

Question

<many-to-one name="user" class="com.xyz.beans.User" lazy="false" fetch="join">
    <column name="startedBy" />
</many-to-one>
<many-to-one name="participantByParticipant1" class="com.xyz.beans.Participant" lazy="false" fetch="join" cascade="all" >
    <column name="participant1" />
</many-to-one>
<many-to-one name="participantByParticipant2" class="com.xyz.beans.Participant" lazy="false" fetch="join" cascade="all">
    <column name="participant2" />
</many-to-one>

Query query = session.createQuery("from Post as p order by challenge.createdOn desc");
query.setFirstResult(0);
query.setMaxResults(10);

Answer 1

在映射中设置lazy=“false”fetch=“join”只有在直接获得实体时才会产生效果：

session.get(Post.class, postId);

当您执行查询时，您需要显式地声明您的fetch策略。否则它还是会偷懒：

from Post as p left join fetch p.user

像往常一样，这个规则有许多变体和例外。您可以在Hibernate文档16.3中找到更多。协会和加入。