OpenJPA MapJoin key() 抛出 NullPointerException答案

【问题标题】：OpenJPA MapJoin key() throws NullPointerExceptionOpenJPA MapJoin key() 抛出 NullPointerException
【发布时间】：2014-05-08 15:04:22
【问题描述】：

我正在尝试对本地化字符串进行搜索。字符串由 Map 映射

这是实体：

@Entity
@Table(name="category", schema="myschema")
@Access(AccessType.FIELD)
public class Category {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    Long id;

    @ElementCollection(fetch=FetchType.EAGER)
    Map<String, String> test = new HashMap<String, String>();

...
}

这里是查询：

Locale locale = Locale.ENGLISH;
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<Category> criteria = cb.createQuery(Category.class);
Root<Category> category = criteria.from(Category.class);
criteria.select(category);
MapJoin<Category, String, String> tests = category.join(Category_.test);

Predicate searchClause = cb.and(
                                cb.equal(tests.key(), locale.toString()), 
                                cb.like(tests.value(), search)
                               );

entityManager.createQuery(criteria).getResultList();

当查询被执行时，我得到这个堆栈跟踪：

[err] java.lang.NullPointerException
[err]   at org.apache.openjpa.jdbc.kernel.exps.PCPath.<init>(PCPath.java:105)
[err]   at org.apache.openjpa.jdbc.kernel.exps.JDBCExpressionFactory.newPath(JDBCExpressionFactory.java:302)
[err]   at org.apache.openjpa.persistence.criteria.Joins$MapKey.toValue(Joins.java:625)
[err]   at org.apache.openjpa.persistence.criteria.Expressions.toValue(Expressions.java:66)
[err]   at org.apache.openjpa.persistence.criteria.Expressions$Equal.toKernelExpression(Expressions.java:851)
[err]   at org.apache.openjpa.persistence.criteria.PredicateImpl.toKernelExpression(PredicateImpl.java:171)
[err]   at org.apache.openjpa.persistence.criteria.CriteriaExpressionBuilder.evalFilter(CriteriaExpressionBuilder.java:216)
[err]   at org.apache.openjpa.persistence.criteria.CriteriaExpressionBuilder.getQueryExpressions(CriteriaExpressionBuilder.java:75)
[err]   at org.apache.openjpa.persistence.criteria.CriteriaQueryImpl.getQueryExpressions(CriteriaQueryImpl.java:418)
[err]   at org.apache.openjpa.persistence.criteria.CriteriaBuilderImpl.eval(CriteriaBuilderImpl.java:83)
[err]   at org.apache.openjpa.kernel.ExpressionStoreQuery$DataStoreExecutor.<init>(ExpressionStoreQuery.java:763)
[err]   at org.apache.openjpa.kernel.ExpressionStoreQuery.newDataStoreExecutor(ExpressionStoreQuery.java:179)
[err]   at org.apache.openjpa.kernel.QueryImpl.createExecutor(QueryImpl.java:749)

我不知道可能出了什么问题。显然 key() 函数不能正常工作。

我正在使用 openjpa-2.2.3-SNAPSHOT-r422266

【问题讨论】：

标签： java jpa nullpointerexception openjpa

【解决方案1】：

闻起来像虫子。请举报JIRA against OpenJPA.

【讨论】：