覆盖休眠映射文件中相关实体的延迟加载设置

发布于 2024-12-14 11:08:14 字数 844 浏览 0 评论 0原文

我有一个映射文件，它为一些相关实体设置lazy=false。这对于很多用例来说都是有意义的，但也有一些例外。问题是我不想在这些情况的查询时获取相关关联，这在时间上非常昂贵。

实体的映射示例。

<class name="Category" table="category">
    <id name="id" type="string">
      <column length="50" name="id"/>
      <generator class="uuid"/>
    </id>
    <property name="name" type="string">
      <column length="100" name="name" not-null="true"/>
    </property>
    <set inverse="true" lazy="false" name="categorySourcesList">
      <key>
        <column length="50" name="categoryid" not-null="true"/>
      </key>
      <one-to-many class="CategorySource"/>
    </set>
  </class>

我的问题是，有没有一种方法可以覆盖映射文件中设置的 lazy 值，无论是在我自定义编写的 sql-query 中还是启用延迟加载DAO 中的参数？或者通过一些注释？

原文

I have a mapping file which sets lazy=false for some related entities. This makes sense for a lot of use cases but there are some exceptions. The problem is that I dont want to fetch the related associations at query time for these cases, which are very expensive time-wise.

Example of the mapping for the entity.

<class name="Category" table="category">
    <id name="id" type="string">
      <column length="50" name="id"/>
      <generator class="uuid"/>
    </id>
    <property name="name" type="string">
      <column length="100" name="name" not-null="true"/>
    </property>
    <set inverse="true" lazy="false" name="categorySourcesList">
      <key>
        <column length="50" name="categoryid" not-null="true"/>
      </key>
      <one-to-many class="CategorySource"/>
    </set>
  </class>

My question is, is there a way to override the lazy value which is set in the mapping file, either in the sql-query I custom write or enabling lazy load as one of the parameters in the DAO? or through some annotations?

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朦胧时间 2024-12-21 11:08:14

是的，您可以覆盖带注释或 xml 映射的关联获取策略。

Hibernate 文档

    Criteria criteria = session().createCriteria(MyClass.class);
    criteria.add(Restrictions.eq("id", "1234"));        
    criteria.setFetchMode("children",FetchMode.EAGER);
    return (MyClass) criteria.uniqueResult();

这将返回您有一个 MyClass 实例，并且急切地获取了它的子级。

Yes, you can override the annotated or xml mapped association fetching strategy.

Hibernate Documentation

    Criteria criteria = session().createCriteria(MyClass.class);
    criteria.add(Restrictions.eq("id", "1234"));        
    criteria.setFetchMode("children",FetchMode.EAGER);
    return (MyClass) criteria.uniqueResult();

This will return you an instance of MyClass with its children eagerly fetched.

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