如何在持久化后刷新缓存？ [英] How to refresh cache after persist?

问题描述

我正在使用JPA（EclipseLink 2.5）来实现持久性。我的网络应用程序包含AJAX页面更新。保存帖子后，发布的内容会在不刷新浏览器的情况下显示。帖子使用OneToMany关系标记了与之关联的标签。这些标签也应该在保存后显示出来。但是，由于缓存已启用，因此无法获取标记。

I am using JPA (EclipseLink 2.5) for persistence. My web app contains AJAX page updates. When a post is saved, the posted content shows up without refreshing the browser. The post have tags associated with it using a OneToMany relationship. These tags are supposed to show up after save too. However, because the cache was enabled I was not able to get the tags.

这是我的代码：

   @TransactionAttribute(TransactionAttributeType.REQUIRED)
public Sqask save(AskTag tags) {
    try {
        Sqask ask = saveAsk(tags);
        return ask;
    } catch (Exception e) {
        context.setRollbackOnly();
        return null;
    }
}

public Sqask saveAsk(AskTag tags) {
        Sqask ask = new Sqask();
        ask.setCreator(tags.getAskedBy());
        em.persist(ask);
        em.flush();
        saveTags(tags, ask);
        return ask;
    }

public void saveTags(AskTag tags, Sqask ask) {
        if (!tags.getNask().isEmpty()) {
            NAsk nask = new NAsk();
            NAskPK naskPK = new NAskPK();
            naskPK.setAsk(ask.getId());
            naskPK.setNoun(tags.getNask());
            naskPK.setCreator(tags.getAskedBy().getGuid());
            nask.setNAskPK(naskPK);
            nask.setAsk(ask);
            nask.setCreator(tags.getAskedBy());
            em.persist(nask);
        }

        if (!tags.getVask().isEmpty()) {
            VAsk vask = new VAsk();
            VAskPK vaskPK = new VAskPK();
            vaskPK.setAsk(ask.getId());
            vaskPK.setVerb(tags.getVask());
            vaskPK.setCreator(tags.getAskedBy().getGuid());
            vask.setVAskPK(vaskPK);
            vask.setAsk(ask);
            vask.setCreator(tags.getAskedBy());
            em.persist(vask);
        }

        if (!tags.getForask().isEmpty()) {
            PAsk forask = new PAsk();
            PAskPK foraskPK = new PAskPK();
            foraskPK.setAsk(ask.getId());
            foraskPK.setPrep(tags.getForask());
            foraskPK.setCreator(tags.getAskedBy().getGuid());
            forask.setPAskPK(foraskPK);
            forask.setAsk(ask);
            forask.setCreator(tags.getAskedBy());
            em.persist(forask);
        }

        if (!tags.getAboutask().isEmpty()) {
            PAsk aboutask = new PAsk();
            PAskPK aboutaskPK = new PAskPK();
            aboutaskPK.setAsk(ask.getId());
            aboutaskPK.setPrep(tags.getAboutask());
            aboutaskPK.setCreator(tags.getAskedBy().getGuid());
            aboutask.setPAskPK(aboutaskPK);
            aboutask.setAsk(ask);
            aboutask.setCreator(tags.getAskedBy());
            em.persist(aboutask);
        }

        em.getEntityManagerFactory().getCache().evict(Sqask.class, ask.getId());
        em.merge(ask);
}

我怎样才能让事情发挥作用？如何使用其所有关联实体刷新实体？谢谢。

How can I get things to work? How to refresh an entity with all its associated entities? Thanks.

推荐答案

如果我理解你的问题可能会对你有帮助 - 请在返回前注意em.refresh电话。这确保即使您只保存相关记录的ID，也会刷新所有OneToOne和OneToMany连接。

If I understand your question correctly maybe this could help you - please notice em.refresh call before returning. This ensured that all OneToOne and OneToMany joins are refreshed, even if you are only saving an ID of related record.

public T create(T entity) {
  em.persist(entity);
  em.flush();
  em.refresh(entity); // this could be important
  return entity;
}

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