NPE when trying to invoke FieldMetada.getOrders() when a PersistenCollection
field is being loaded.
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Key: OPENJPA-562
URL: https://issues.apache.org/jira/browse/OPENJPA-562
Project: OpenJPA
Issue Type: Bug
Components: kernel
Affects Versions: 1.1.0
Environment: This error occured on Microsoft Windows XP SP2, Java
version = 1.6.0 with mySQL 5.0 Database.
Reporter: Sandeep Shrivastava
Fix For: 1.1.0
Consider the following snippet of an entity definition:
/**
* <p>Entity used to test parsing of @OrderBy.</p>
*
* @author Abe White
*/
@Entity
public class OrderByEntity {
@Id
private long id;
private String string;
@PersistentCollection
@OrderBy
private List<String> strings = new ArrayList();
}
The @PersistentCollection annotation maps the declaration to the default
collection table named orderbyentity_strings. The join column name in the
container table is also defaulted to orderbyentity_id and the name of the
Element column name is defaulted to element.
The test code initially added string elements to the strings list and persisted
it.
OrderByEntity pc = new OrderByEntity();
pc.setId(1L);
pc.getStrings().add("2");
pc.getStrings().add("1");
pc.getStrings().add("3");
On a subsequent load of the persistent collection data by executing the
following code, we hit into an NPE.
pc = em.find(OrderByEntity.class, 1L);
List<String> strings = pc.getStrings();
java.lang.NullPointerException
at org.apache.openjpa.meta.FieldMetaData.getOrders(FieldMetaData.java:1127)
at
org.apache.openjpa.jdbc.meta.strats.StoreCollectionFieldStrategy.selectEager(StoreCollectionFieldStrategy.java:207)
at
org.apache.openjpa.jdbc.meta.strats.StoreCollectionFieldStrategy.selectEagerJoin(StoreCollectionFieldStrategy.java:171)
at
org.apache.openjpa.jdbc.meta.FieldMapping.selectEagerJoin(FieldMapping.java:713)
at
org.apache.openjpa.jdbc.kernel.JDBCStoreManager.select(JDBCStoreManager.java:927)
at
org.apache.openjpa.jdbc.kernel.JDBCStoreManager.load(JDBCStoreManager.java:503)
at
org.apache.openjpa.kernel.DelegatingStoreManager.load(DelegatingStoreManager.java:116)
at
org.apache.openjpa.datacache.DataCacheStoreManager.load(DataCacheStoreManager.java:368)
at
org.apache.openjpa.kernel.DelegatingStoreManager.load(DelegatingStoreManager.java:116)
at org.apache.openjpa.kernel.ROPStoreManager.load(ROPStoreManager.java:78)
at
org.apache.openjpa.kernel.StateManagerImpl.loadFields(StateManagerImpl.java:2911)
at
org.apache.openjpa.kernel.StateManagerImpl.loadField(StateManagerImpl.java:2989)
at kodo.kernel.ProfilingStateManager.loadField(ProfilingStateManager.java:68)
at
org.apache.openjpa.kernel.StateManagerImpl.beforeAccessField(StateManagerImpl.java:1489)
at
kodo.kernel.ProfilingStateManager.beforeAccessField(ProfilingStateManager.java:49)
at
org.apache.openjpa.kernel.StateManagerImpl.accessingField(StateManagerImpl.java:1474)
This problem is reported with OpenJPA version:
$ java org.apache.openjpa.conf.OpenJPAVersion
OpenJPA 1.1.0-SNAPSHOT
version id: openjpa-1.1.0-SNAPSHOT-r420667:634150
Apache svn revision: 420667:634150
os.name: Windows XP
os.version: 5.1
os.arch: x86
java.version: 1.6.0_05
java.vendor: BEA Systems, Inc.
The NPE occurs when the FieldMetadata.getOrders() method is invoked when trying
to load the data in the strings collection field. The code is trying to get the
ClassMetadata for the element type and then check the FieldMetadata is present
in the declared fields. It fails because the element data type is
java.lang.String and there is no ClassMetadata for it. By simply adding a null
check for the returned class metadata this issue I could fix locally.
Here is the outout of the svn diff command.
C:\apache_openjpa_project\openjpa>svn diff
Index: openjpa-kernel/src/main/java/org/apache/openjpa/meta/FieldMetaData.java
===================================================================
--- openjpa-kernel/src/main/java/org/apache/openjpa/meta/FieldMetaData.java
(revision 643944)
+++ openjpa-kernel/src/main/java/org/apache/openjpa/meta/FieldMetaData.java
(working copy)
@@ -1124,9 +1124,11 @@
//set "isUsedInOrderBy" to the field
ClassMetaData elemCls = getElement()
.getDeclaredTypeMetaData();
- FieldMetaData fmd = elemCls.getDeclaredField(decs[i]);
- if (fmd != null)
- fmd.setUsedInOrderBy(true);
+ if (elemCls != null) {
+ FieldMetaData fmd = elemCls.getDeclaredField(decs[i]);
+ if (fmd != null)
+ fmd.setUsedInOrderBy(true);
+ }
}
_orders = orders;
}
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