1

这是我的 JPA 查询：

String jpql = "SELECT a FROM Account a WHERE a.id IN :list";
TypedQuery<Account> q = mgr.createQuery(jpql, Account.class);
q.setParameter("list", list);
return q.getResultList();

这是错误日志：

Cannot find type of (part of) a.id since symbol has no type; implicit variable?
org.datanucleus.exceptions.NucleusUserException: Cannot find type of (part of) a.id since symbol has no type; implicit variable?
    at org.datanucleus.query.expression.PrimaryExpression.bind(PrimaryExpression.java:274)
    at org.datanucleus.query.expression.DyadicExpression.bind(DyadicExpression.java:87)
    at org.datanucleus.query.compiler.JavaQueryCompiler.compileFilter(JavaQueryCompiler.java:480)
    at org.datanucleus.query.compiler.JPQLCompiler.compile(JPQLCompiler.java:81)
    at org.datanucleus.store.query.AbstractJPQLQuery.compileInternal(AbstractJPQLQuery.java:271)
    at org.datanucleus.store.query.Query.setImplicitParameter(Query.java:799)
    at org.datanucleus.api.jpa.JPAQuery.setParameter(JPAQuery.java:437)
    at org.datanucleus.api.jpa.JPAQuery.setParameter(JPAQuery.java:57)
    at com.example.game.dao.impl.AccountDaoImpl.findByIds(AccountDaoImpl.java:42)
    at com.example.game.gameApi.sendPuzzle(gameApi.java:123)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.appengine.tools.development.agent.runtime.Runtime.invoke(Runtime.java:115)
    at com.google.api.server.spi.SystemService.invokeServiceMethod(SystemService.java:304)
    at com.google.api.server.spi.SystemServiceServlet.execute(SystemServiceServlet.java:161)
    at com.google.api.server.spi.SystemServiceServlet.doPost(SystemServiceServlet.java:120)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
    at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:123)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:61)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.DevAppServerServersFilter.doFilter(DevAppServerServersFilter.java:106)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
    at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:94)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:421)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
    at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)

此外，帐户看起来像这样

@Entity
public class Account implements java.io.Serializable{
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Key key;

    private String name;


    public Account(long id, name) {
        super();
        Key key = KeyFactory.createKey(Account.class.getSimpleName(), id);
        this.key = key;
           this.name = name
    }

//getters and setters

}

对于对应物，在 python 中，数据存储支持多键查询，类似于

list_of_keys = ndb.put_multi(list_of_entities)
list_of_entities = ndb.get_multi(list_of_keys)
ndb.delete_multi(list_of_keys)

正如本教程所建议的那样，使用循环将是低效的。

4

2 回答 2

1

我想你希望你的查询是：

String jpql = "SELECT a FROM Account a WHERE a.key IN :list";

因为变量被命名为key，而不是id。

于 2013-06-15T18:34:03.800 回答
0

我不知道 JPA 是否允许你正在寻找的东西，但你绝对可以使用一个DatastoreService对象来做到这一点，如

DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();

从那里，您可以使用您的 python 应用程序引擎知识来指导您。如果您已经开发了很长时间，那么您可能不得不使用 Hibernate 来补充 JPA。如果您真的想对界面进行编码，那么您可能不喜欢这个答案。但这是一个与使用 Hibernate 没有什么不同的解决方案。

于 2013-04-09T21:04:14.750 回答