java - 如何在 AppEngine 中使用 JPA 2 获取实体、在 GWT 中更新并保存？

Question

在 GWT 中更新一些实体后，我想保存它们。但是，当我尝试保留它们时，当我查看 AppEngine 管理界面时，它不会保存。 boolean 值没有改变。

代码

    EntityManager em = EMF.get().createEntityManager();
    for (OnixUser s: admin) {
        log.info(s.email + ", " + s.isAdmin);
        em.merge(s);  
    }
    em.close();

更新交易

    EntityManager em = EMF.get().createEntityManager();
    em.getTransaction().begin();
    for (OnixUser s: admin) {
        log.info(s.email + ", " + s.isAdmin);
        OnixUser merged = em.merge(s);
        em.persist(merged);
//          em.persist(s);
    }
    em.getTransaction().commit();
    em.close();

还是没有保存。没有抛出异常。

日志

 Oct 16, 2013 3:19:10 PM com.example.sdm.server.SDMServiceImpl setAdmin
 INFO: chloe@example.com, true

OnixUser 实体的 App Engine 管理界面

以最佳级别登录

FINE: Created ManagedConnection using DatastoreService = com.google.appengine.api.datastore.DatastoreServiceImpl@2fd9270d
Oct 16, 2013 4:03:14 PM org.datanucleus.store.connection.ConnectionManagerImpl allocateConnection
FINE: Connection added to the pool : com.google.appengine.datanucleus.DatastoreConnectionFactoryImpl$DatastoreManagedConnection@31c1f89d for key=org.datanucleus.ObjectManagerImpl@6977c57b in factory=ConnectionFactory:tx[com.google.appengine.datanucleus.DatastoreConnectionFactoryImpl@2b1f5f6b]
Oct 16, 2013 4:03:14 PM com.example.sdm.server.SDMServiceImpl setAdmin
INFO: chloe@example.com, true
Oct 16, 2013 4:03:14 PM org.datanucleus.state.LifeCycleState changeState
FINE: Object "com.example.sdm.shared.OnixUser@48ef6e99" (id="com.example.sdm.shared.OnixUser:6456332278300672") has a lifecycle change : "P_CLEAN"->"P_NONTRANS"
Oct 16, 2013 4:03:14 PM org.datanucleus.store.connection.ConnectionManagerImpl$1 managedConnectionPostClose
FINE: Connection removed from the pool : com.google.appengine.datanucleus.DatastoreConnectionFactoryImpl$DatastoreManagedConnection@31c1f89d for key=org.datanucleus.ObjectManagerImpl@6977c57b in factory=ConnectionFactory:tx[com.google.appengine.datanucleus.DatastoreConnectionFactoryImpl@2b1f5f6b]
Oct 16, 2013 4:03:14 PM org.datanucleus.state.LifeCycleState changeState
FINE: Object "com.example.sdm.shared.OnixUser@48ef6e99" (id="com.example.sdm.shared.OnixUser:6456332278300672") has a lifecycle change : "P_NONTRANS"->"DETACHED_CLEAN"
Oct 16, 2013 4:03:14 PM com.google.apphosting.utils.jetty.AppEngineAuthentication$AppEngineUserRealm disassociate
FINE: Ignoring disassociate call for: chloe@example.com

Answer 1

如果尽管使用事务，您的数据并未持久保存，那么最好的方法是尝试记录日志以查看底层发生了什么。当您使用 DataNucleus 作为持久性提供程序时，您可以引用此 link配置 SQL 日志记录。与您相关的信息位于页面末尾附近。