-->
These old forums are deprecated now and set to read-only. We are waiting for you on our new forums!
More modern, Discourse-based and with GitHub/Google/Twitter authentication built-in.

All times are UTC - 5 hours [ DST ]



Forum locked This topic is locked, you cannot edit posts or make further replies.  [ 1 post ] 
Author Message
 Post subject: Metamodel NullPointerException Problem
PostPosted: Mon Mar 07, 2011 2:02 pm 
Newbie

Joined: Wed Apr 14, 2010 8:18 pm
Posts: 1
If someone could assist me in putting me back on track. I have a slight problem with using the Metamodel in helping with building queries.

Here are the relevent code snippets:

User.java
Code:
package votify.domain;
@Entity
@Table(name="VOTE_USER")
public class User implements Serializable {
    public static final String PROP_NAME = "name";
    public static final String PROP_CYCLESET = "cycleSet";
    public static final String PROP_PWD = "pwd";
   
    @Column(name="USERNAME", nullable=false)
    protected String name;


UserMeta.java (I know the convention is User_.java)
Code:
package votify.domain;
@StaticMetamodel(User.class)
public class UserMeta {
    public static volatile SingularAttribute<User, Long> id;
    public static volatile SingularAttribute<User, String> name;
}


UserManager.java
Code:
  1 package votify.manager;
.....
25 @Repository
26 public class UserManager implements Serializable {
27
28    @PersistenceContext(unitName = "VotifyPU")
29    private EntityManager em;
......
108    public User findUserByName(String username) {
109        CriteriaBuilder builder = em.getCriteriaBuilder();
110        CriteriaQuery<User> query = builder.createQuery(User.class);
111        Root<User> userRoot = query.from(User.class);
112        SingularAttribute<User, String> usernameAttr = UserMeta.name;
113//        Path<String> aPath = userRoot.get("name");
114        Path<String> aPath = userRoot.get(UserMeta.name);
115        Expression<Boolean> isTrue = builder.equal(aPath, username);
116        query.select(userRoot);
117        query.where(isTrue);
118
119        TypedQuery<User> tQuery = em.createQuery(query);
120        User u = null;
121        try {
122            u = tQuery.getSingleResult();
123        } catch (Exception e) {
124            u = null;
125        }
126        return u;
127    }


UserManagerTest.java
Code:
1       package votify.manager;
134    @Test
135    public void findByName() {
136        String name = "Sizzle";
137        User user = userManager.findUserByName(name);
138        assertNotNull(user);
139    }


Output: (LogBack)
Code:
Testcase: findByName(votify.manager.UserManagerTest):        Caused an ERROR
null
java.lang.NullPointerException
        at org.hibernate.ejb.criteria.path.AbstractPathImpl.get(AbstractPathImpl.java:138)
        at votify.manager.UserManager.findUserByName(UserManager.java:114)
        at votify.manager.UserManagerTest.findByName(UserManagerTest.java:137)
        at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
        at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:82)


The weird thing is, if in the UserManager file, I comment out line 114 and instead use line 113, the test completes successfully.
I hope I have given enough information to solve this problem. (Or to say, "Hey, dummy, you forgot such and such.") :)


Top
 Profile  
 
Display posts from previous:  Sort by  
Forum locked This topic is locked, you cannot edit posts or make further replies.  [ 1 post ] 

All times are UTC - 5 hours [ DST ]


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
© Copyright 2014, Red Hat Inc. All rights reserved. JBoss and Hibernate are registered trademarks and servicemarks of Red Hat, Inc.