读取持久对象的变量可以防止以后将其添加到对象中

Question

我正在尝试创建一个新对象 Session 并将其保存到数据库中。它有一个持久变量 User 对象。我在数据库中查询要添加到会话中的用户。如果用户的密码与“hello”不匹配（显然现在是这样），请停止。如果是，则创建一个新会话，设置常规变量并添加 sOwner（只需设置会话的 User 变量）。像这样，代码可以工作，但不会检查密码...

try {
    Query u = pm.newQuery(User.class); //Query for user
    u.setFilter("email == eaddr");
    u.declareImports("import java.lang.String");
    u.declareParameters("String eaddr");
    @SuppressWarnings("unchecked")
    List<User> res = (List<User>)u.execute(email);
    sOwner = res.get(0);
    //if (!sOwner.getPassword().equals("hello")) {  // comment out
    //throw new Exception("password not correct");  // these three lines
    //}                                 // and it works
    sNew = new Session();
    sNew.setUser(sOwner);
    sNew.setIpAddr(ipAddr);
    sNew.setStartedOn(new Date());
    sNew.setToken(token);
    pm.makePersistent(sNew);
} catch (Exception e) {
}

但是如果没有注释掉 if 语句，最终提交的更改会出现此错误：

2385571 [btpool0-0] DEBUG DataNucleus.Persistence  - Object "com.yachtcloser.server.om.Session@14446bce" (id="com.yachtcloser.server.om.Session:381") is having the value in field "startedOn" replaced by a SCO wrapper
2385571 [btpool0-0] DEBUG DataNucleus.Datastore.Native  - INSERT INTO `SESSION` (`TOKEN`,`STARTEDON`,`USERAGENT`,`IPADDR`,`USER_ID_OID`,`ID`) VALUES (<'90a9d90f325c3b'>,<2011-02-24 19:12:15.595>,<null>,<'127.0.0.5'>,<21>,<381>)
2385572 [btpool0-0] DEBUG DataNucleus.Datastore.Persist  - Execution Time = 1 ms (number of rows = 1)
2385572 [btpool0-0] DEBUG DataNucleus.Persistence  - Insert of object "com.yachtcloser.server.om.Session@14446bce" is calling insertPostProcessing for field "com.yachtcloser.server.om.Session.user"
2385572 [btpool0-0] DEBUG DataNucleus.Persistence  - Insert of object "com.yachtcloser.server.om.Session@14446bce" is calling insertPostProcessing for field "com.yachtcloser.server.om.Session.transaction"
2385572 [btpool0-0] DEBUG DataNucleus.Datastore.Retrieve  - Closing PreparedStatement org.datanucleus.store.rdbms.ParamLoggingPreparedStatement@2ac7bf18
2385572 [btpool0-0] DEBUG DataNucleus.Persistence  - Insert of object "com.yachtcloser.server.om.Session@14446bce" is calling postInsert for field "com.yachtcloser.server.om.Session.user"
2385572 [btpool0-0] DEBUG DataNucleus.Persistence  - Insert of object "com.yachtcloser.server.om.Session@14446bce" is calling postInsert for field "com.yachtcloser.server.om.Session.transaction"
2385584 [btpool0-0] DEBUG DataNucleus.Persistence  - Object "com.yachtcloser.server.om.Session@14446bce" field "transaction" is replaced by a SCO wrapper of type "org.datanucleus.store.types.sco.backed.List" [cache-values=true, lazy-loading=true, queued-operations=false, allow-nulls=true]
2385585 [btpool0-0] DEBUG com.yachtcloser.server.DispatchServlet  - Response Sent:{"cmds":[{"response":"Session 381 created by user 0"}]}
2385585 [btpool0-0] DEBUG DataNucleus.Persistence  - ObjectManager internalFlush() process started - 1 dirty objects
2385585 [btpool0-0] DEBUG DataNucleus.Persistence  - ObjectManager internalFlush() process finished
2385589 [btpool0-0] ERROR DataNucleus.Persistence  - java.lang.NullPointerException
2385590 [btpool0-0] DEBUG DataNucleus.Persistence  - Disconnecting com.yachtcloser.server.om.Session@14446bce from StateManager[pc=com.yachtcloser.server.om.Session@14446bce, lifecycle=P_NEW]

这是我认为的 NPE 的堆栈跟踪：

NestedThrowablesStackTrace:
java.lang.NullPointerException
    at org.datanucleus.store.rdbms.sql.SQLStatementHelper.selectMemberOfSourceInStatement(SQLStatementHelper.java:723)
    at org.datanucleus.store.rdbms.request.FetchRequest.processMembersOfClass(FetchRequest.java:478)
    at org.datanucleus.store.rdbms.request.FetchRequest.<init>(FetchRequest.java:166)
    at org.datanucleus.store.rdbms.RDBMSPersistenceHandler.getFetchRequest(RDBMSPersistenceHandler.java:329)
    at org.datanucleus.store.rdbms.RDBMSPersistenceHandler.fetchObject(RDBMSPersistenceHandler.java:306)
    at org.datanucleus.jdo.state.JDOStateManagerImpl.loadFieldsFromDatastore(JDOStateManagerImpl.java:2028)
    at org.datanucleus.jdo.state.JDOStateManagerImpl.loadUnloadedFields(JDOStateManagerImpl.java:1685)
    at org.datanucleus.jdo.state.JDOStateManagerImpl.runReachability(JDOStateManagerImpl.java:3295)
    at org.datanucleus.ObjectManagerImpl.performReachabilityAtCommit(ObjectManagerImpl.java:3415)
    at org.datanucleus.ObjectManagerImpl.preCommit(ObjectManagerImpl.java:3268)
    at org.datanucleus.ObjectManagerImpl$2.transactionPreCommit(ObjectManagerImpl.java:324)
    at org.datanucleus.TransactionImpl.internalPreCommit(TransactionImpl.java:394)
    at org.datanucleus.TransactionImpl.commit(TransactionImpl.java:279)
    at org.datanucleus.jdo.JDOTransaction.commit(JDOTransaction.java:90)
    at com.yachtcloser.server.UserContext.finishRequest(UserContext.java:181)
    at com.yachtcloser.server.DispatchServlet.doPost(DispatchServlet.java:185)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at com.yachtcloser.server.DispatchServlet.service(DispatchServlet.java:55)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:362)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.handler.RequestLogHandler.handle(RequestLogHandler.java:49)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:324)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:843)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:647)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
        at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)

我尝试分离副本，并比较该密码，然后添加原始查询结果 到会议上，这也不起作用。这是会话的重要部分，我无法编辑：

@PersistenceCapable(identityType=IdentityType.APPLICATION)
public class Session  implements Comparable<Session> {

    @PrimaryKey
  @Persistent(valueStrategy=IdGeneratorStrategy.INCREMENT)
  private long id;

  @Persistent
  private User user;

datanucleus-core-2.2.2.jar、datanucleus-connectionpool-2.0.3.jar、datanucleus-googlecollections-2.2.0-release.jar、datanucleus- jdo-query-2.2.1.jar、datanucleus-rdbms-2.2.2.jar、jdo2-api-2.3-ec.jar、datanucleus-enhancer-2.1.3.jar、asm-3.3.1.jar 这些是我看到的jar文件

Answer 1

查询生成 SQL。这会打印在 DataNucleus 日志中。因此，您应该检查为您的查询生成的 SQL。堆栈跟踪是从 tx.commit() 创建的，但您没有提到这样的调用。

你没有说每个插件 jar 正在使用的 DataNucleus 版本。