What is wrong with this JPQL query?

Question

I'm trying to execute the fallowing query on my server Here is my query:

List<Object> result = entityManager
    .createQuery("SELECT post FROM PostMW post LEFT OUTER JOIN LikeMW likes ON post.id = likes.post_id AND likes.user_id =:userID")
    .setParameter("userID", 1)
    .setFirstResult(offset).setMaxResults(itemsPerPage)
    .getResultList();

Object PostMW (not complete but with the necessary data I'd say):

@Entity
@Table(name="POST")
public class PostMW{

    @Id
    @Column(name="id", nullable=false)
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;

    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name="media_id", nullable=false, unique=true)
    private MediaMW media;

    @Column(name="latitude", nullable=false)
    private BigDecimal latitude;

    @Column(name="longitude", nullable=false)
    private BigDecimal longitude;

    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name="challenge_id", nullable=false)
    private ChallengeMW challenge;

    // GETTERS AND SETTERS //
    ....
}

Here is LikeMW (complete) so how you see, it has just two primary keys from table USER and POST:

@Entity
@Table(name="LIKES")
public class LikeMW {

    @Id
    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "post_id", nullable=false)
    @JsonBackReference
    private PostMW post;

    @Id
    @ManyToOne(cascade = CascadeType.ALL)
    @JoinColumn(name="user_id", nullable=false)
    private UserMW user;

    // GETTERS AND SETTERS //
    ...
}

I'm receiving nullpointerException! I can't figure out why... Exception:

java.lang.IllegalArgumentException: An exception occurred while creating a query in EntityManager: 
Exception Description: Internal problem encountered while compiling [SELECT post FROM PostMW post LEFT OUTER JOIN LikeMW likes ON post.id = likes.post_id AND likes.user_id =:userID].
Internal Exception: java.lang.NullPointerException
at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1605)
at com.jonathan.myworld.model.dao.impl.PostDaoImpl.list(PostDaoImpl.java:72)
at com.jonathan.myworld.service.impl.FeedServiceImpl.getFeed(FeedServiceImpl.java:45)
at com.jonathan.myworld.UserWS.login(UserWS.java:151)
at com.jonathan.myworld.UserWS.loginWithGoogle(UserWS.java:60)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.google.appengine.tools.development.agent.runtime.Runtime.invoke(Runtime.java:130)
at com.google.api.server.spi.SystemService.invokeServiceMethod(SystemService.java:363)
at com.google.api.server.spi.SystemServiceServlet.execute(SystemServiceServlet.java:113)
at com.google.api.server.spi.SystemServiceServlet.doPost(SystemServiceServlet.java:71)
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:128)
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:63)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:50)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectRequest(DevAppServerModulesFilter.java:366)
at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectModuleRequest(DevAppServerModulesFilter.java:349)
at com.google.appengine.tools.development.DevAppServerModulesFilter.doFilter(DevAppServerModulesFilter.java:116)
at org.mortbay.jetty.servlet.ServletHandler$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:98)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:511)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$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)
Caused by: Exception [EclipseLink-0] (Eclipse Persistence Services - 2.5.1.v20130918-f2b9fc5): org.eclipse.persistence.exceptions.JPQLException
Exception Description: Internal problem encountered while compiling [SELECT post FROM PostMW post LEFT OUTER JOIN LikeMW likes ON post.id = likes.post_id AND likes.user_id =:userID].
Internal Exception: java.lang.NullPointerException
at org.eclipse.persistence.internal.jpa.jpql.HermesParser.buildUnexpectedException(HermesParser.java:207)
at org.eclipse.persistence.internal.jpa.jpql.HermesParser.populateQueryImp(HermesParser.java:296)
at org.eclipse.persistence.internal.jpa.jpql.HermesParser.buildQuery(HermesParser.java:163)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:142)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.buildEJBQLDatabaseQuery(EJBQueryImpl.java:116)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:102)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.<init>(EJBQueryImpl.java:86)
at org.eclipse.persistence.internal.jpa.EntityManagerImpl.createQuery(EntityManagerImpl.java:1603)
... 49 more
Caused by: java.lang.NullPointerException
at org.eclipse.persistence.queries.DatabaseQuery.addArgument(DatabaseQuery.java:449)
at org.eclipse.persistence.queries.DatabaseQuery.addArgument(DatabaseQuery.java:419)
at org.eclipse.persistence.internal.jpa.jpql.HermesParser.addArguments(HermesParser.java:98)
at org.eclipse.persistence.internal.jpa.jpql.HermesParser.populateQueryImp(HermesParser.java:287)

I can't find what I'm doing wrong. Any suggestion will be very appreciated!

EDIT:

Trying this query at moment:

List<Object> result = entityManager
                .createQuery("SELECT post FROM PostMW post LEFT OUTER JOIN post.hasLiked liked ON post.id = liked.post_id AND liked.user_id =:userID")
                .setParameter("userID", 1)
                .setFirstResult(offset).setMaxResults(itemsPerPage)
                .getResultList();

Updated my objects. Now my PostMW object has

@Entity
@Table(name="POST")
public class PostMW{
    ...
    @ManyToMany(cascade = CascadeType.ALL)
    @JoinTable(name="LIKES", joinColumns=@JoinColumn(name="post_id"), inverseJoinColumns=@JoinColumn(name="user_id"))
    private List<UserMW> hasLiked;
    ...
}

And UserMW has

@Entity
@Table(name="USER")
public class UserMW {
    ...
    @Id
    @Column(name="id", nullable=false)
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;

    @Column(name="name", nullable=false, length=255)
    private String name;
    ...
}

Getting the same exception TT

Answer 1

JPQL uses classes/fields and not tables/columns. JPQL != SQL

Answer 2

Is there a null check on the object entityManager used to invoke the createQuery? It could be that this object is null and the java.lang.NullPointerException is being thrown at that line.

Answer 3

Your JPQL is malformed. There is no JOIN...ON in JPQL.

Since you don't have a reference from Post to Like , you can to invert your query to something along the lines of

SELECT likes.post FROM LikeMW likes WHERE likes.user.id = :userID

Which would get the posts like by the user with the given userID.

You'll also want to add an order by to your query if you intend to use offset/limit.

Answer 4

The exact same error was reported as bug at:

https://bugs.eclipse.org/bugs/show_bug.cgi?id=394033

and then again at glassfish bugs: https://java.net/jira/si/jira.issueviews:issue-html/GLASSFISH-20456/GLASSFISH-20456.html

Can you verify if you are using the EclipseLink version with the fix?