unidirectional Set:PropertyAccessException: field value

Gumble · **Joined:** Mon Nov 28, 2005 12:07 pm **Posts:** 17

Hallo there :)
I have a 'Data' Object that can have many Comments (0...n). The 'Comment'-Object doesnt have to know to what 'Data' it is refering to. (unidirectional relationship). Implemented is a Hashset in the 'Data' Object to store the 'Comment'.
What is wrong with:
<set name="comments" cascade="all">
<key column="COMMENTS_" />
<one-to-many class="de.bla.Comment" />
</set>
Thank you in advance for helping me :)

Hibernate version:
Hibernate 3.1 rc3
Name and version of the database you are using:
mysql 5
Mapping documents:
de.bla.Data.hbm.xml

Code:

<hibernate-mapping default-access="field">

   <class name="de.bla.Data" table="ADET_ID_DATA"
      discriminator-value="D">
      <id name="id" column="ID_">
         <generator class="native" />
      </id>
      <discriminator type="char" column="CLASS_" />

      <property name="name" column="NAME_" />

      <property name="initialDate" column="INITDATE_"
         type="java.util.Date" />

      <property name="requestedDate" column="REQDATE_"
         type="java.util.Date" />

      <many-to-one name="omResponsible"
         class="de.bla.User" column="OMRESP_"
         foreign-key="FK_ADET_OMRESP" />

      <many-to-one name="requestor" class="de.bla.User"
         column="REQUESTOR_" foreign-key="FK_ADET_REQUESTOR" />

      <many-to-one name="version" class="de.bla.Version"
         column="VERSION_" foreign-key="FK_ADET_VERSION" />

      <set name="comments" cascade="all">
         <key column="COMMENTS_" />
         <one-to-many class="de.bla.Comment" />
      </set>
   </class>

</hibernate-mapping>

de.bla.Comment.hbm.xml

Code:

<hibernate-mapping default-access="field">

   <class name="de.bla.Comment" table="ADET_ID_COMMENT"
      discriminator-value="C">
      <id name="id" column="ID_">
         <generator class="native" />
      </id>
      <discriminator type="char" column="CLASS_" />
      <property name="name" column="NAME_" />
      <property name="content" column="CONTENT_" />
      <property name="creationDate" column="DATE_" />
      <many-to-one name="creator" class="de.bla.User"
         column="CREATOR_" cascade="all" foreign-key="FK_ADET_USER" />

   </class>

</hibernate-mapping>

Code

Code:

   public void addComment(String crName, String commentText,
         String requestorName) {
      Comment comment = new Comment();
      comment.setContent(commentText);
      comment.setCreationDate(new Date());
      DataSession session = factory.openDataSession();

      User requestor = session.getUserByName(requestorName);
      if (requestor != null)
         comment.setCreator(requestor);
      Data data = session.getDataByName(crName);
      session.beginTransaction();
      data.addComment(comment);
      session.saveData(data);
      session.commitTransactionAndClose();
   }

stack trace:

Caused by: org.hibernate.PropertyAccessException: could not get a field value by reflection getter of de.bla.data.Comment.id

ReneStolp · **Posted:** Sun Jan 15, 2006 9:48 am

Hi!

Hibernate seems to be unable finding the 'id' property in your de.bla.data.Comment class; would be interesting to see the code for that class.

All the best,

René

Gumble · **Joined:** Mon Nov 28, 2005 12:07 pm **Posts:** 17

ReneStolp wrote:

Hi!

Hibernate seems to be unable finding the 'id' property in your de.bla.data.Comment class; would be interesting to see the code for that class.

All the best,

René

But it is existing:

Code:

public class Comment extends Entity implements Serializable {
   private static final long serialVersionUID = 1L;
   protected String content = null;
   protected User creator = null;
   protected Date creationDate = null;
   protected Data referringData = null;
...

The 'id' attribute is inherited from the Entity Object:

Code:

public class Entity implements Serializable {
   private static final long serialVersionUID = 1L;
   long id = 0;
   protected String name = null;
   /* permissions is a set of java.security.Permission's */
   protected Set permissions = null;
...
public long getId() {
      return id;
   }
   
   public void setId(long id) {
      this.id = id;
   }
...

This class is the superclass for other classes, but only 'Comment' didn't work. The Entity Class itself has no hbm-mapping file.
The problem is imho the unidirectional 1-n relationship between 'Data' and 'Comment'. When I am looking directly at the mysql-db, hibernate didn't create any column in the 'Data' Object or any additional mapping table..

ReneStolp · **Posted:** Mon Jan 16, 2006 5:07 am

Hi!

Ok, I see it is there. There are two things that I see, while I do not know, if they are part of the problem:

You are accessing your fields direct, not via getter/setter (by specfying default-access="field").
The field id has no access modifier, making it effectively package private.

I have not tested, if any of this may be the problem, but you can probably easily test it yourself: Try either to modify the access modifier to private or protected and/or change the access type, at least for this field, to getter/setter.

Let me know, if that helped.

All the best,

René

Gumble · **Joined:** Mon Nov 28, 2005 12:07 pm **Posts:** 17

Hmm, that didn't work: whether public oder protected..
It must be the <list> mapping.

Data.hbm.xml

Code:

   <class name="de.bla.Data" table="ADET_ID_DATA"
      discriminator-value="D">
      <id name="id" column="ID_">
         <generator class="native" />
      </id>
      <discriminator type="char" column="CLASS_" />
      ...
      <list name="comments" cascade="all" inverse="true">
        <key column="ID_" />
        <list-index column="COMMENT_INDEX"/>    
        <one-to-many class="de.bla.Comment"/>
      </list>
...

What I dont understand at all:

Code:

mysql> DESCRIBE adet_id_data;
+------------+--------------+------+-----+---------+----------------+
| Field      | Type         | Null | Key | Default | Extra          |
+------------+--------------+------+-----+---------+----------------+
| ID_        | bigint(20)   | NO   | PRI | NULL    | auto_increment |
| CLASS_     | char(1)      | NO   |     |         |                |
| NAME_      | varchar(255) | YES  |     | NULL    |                |
| INITDATE_  | datetime     | YES  |     | NULL    |                |
| REQDATE_   | datetime     | YES  |     | NULL    |                |
| OMRESP_    | bigint(20)   | YES  | MUL | NULL    |                |
| REQUESTOR_ | bigint(20)   | YES  | MUL | NULL    |                |
| VERSION_   | bigint(20)   | YES  | MUL | NULL    |                |
+------------+--------------+------+-----+---------+----------------+
8 rows in set (0.02 sec)

mysql> DESCRIBE adet_id_comment;
+---------------+--------------+------+-----+---------+----------------+
| Field         | Type         | Null | Key | Default | Extra          |
+---------------+--------------+------+-----+---------+----------------+
| ID_           | bigint(20)   | NO   | PRI | NULL    | auto_increment |
| CLASS_        | char(1)      | NO   |     |         |                |
| NAME_         | varchar(255) | YES  |     | NULL    |                |
| CONTENT_      | text         | YES  |     | NULL    |                |
| DATE_         | datetime     | YES  |     | NULL    |                |
| CREATOR_      | bigint(20)   | YES  | MUL | NULL    |                |
| COMMENT_INDEX | int(11)      | YES  |     | NULL    |                |
+---------------+--------------+------+-----+---------+----------------+
7 rows in set (0.02 sec)

I dont understand why there is NO entry in the 'Data' table and there IS A entry in the 'Comment' Table. It should be the other way round, shouldn't it? A 'Data' knows its 'Comments' and thats all.

btw, the current error is when I am trying to add a Comment-Instance to the Data Object (= ArrayList.add( ))

The Code:

Gumble · **Joined:** Mon Nov 28, 2005 12:07 pm **Posts:** 17

I am loosing hope :(
I tried several combinations (1-n, n-n, set/list, lazy, cascade, inverse usw) but in every case one of the two errors occurs (ClassCastException: org.hibernate.collection.PersistentList or PropertyAccessException: could not get a field value).
I think I have also fundamental understanding problems: How to solve the 1-n relationship (data-comment):
a) SQL: in the Data-Table a Column that references to the Comment-Table. This Column is as well as foreign key as primary key.
b) SQL: an extra mapping table with a Data and a Comment Column (both PK and FK)
I am using the 'updata' flag in the cfg-file.

zzyborg · **Posted:** Tue Jan 17, 2006 5:17 am

why dont u try overriding the getter/setters in your persistent class and change to access="property"

Gumble · **Joined:** Mon Nov 28, 2005 12:07 pm **Posts:** 17

Changed access to 'property' and removed the deriving from the Entity class:
Caused by: java.lang.RuntimeException: couldn't commit transaction
at de.bla.data.hibernate.DataSession.commitTransaction(DataSession.java:55)
at de.bladata.hibernate.DataSession.commitTransactionAndClose(DataSession.java:75)
at de.bladata.mbean.DataService.addComment(DataService.java:192)
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:585)
at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:141) ... 33 more
Caused by: org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of de.bla.data.Comment.id
at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:171)
at org.hibernate.tuple.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:176)
at org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:3231)
at org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:2965)
at org.hibernate.engine.ForeignKeys.isTransient(ForeignKeys.java:181)
at org.hibernate.engine.ForeignKeys.getEntityIdentifierIfNotUnsaved(ForeignKeys.java:215)
at org.hibernate.type.EntityType.getIdentifier(EntityType.java:108)
at org.hibernate.type.ManyToOneType.nullSafeSet(ManyToOneType.java:71)
at org.hibernate.persister.collection.AbstractCollectionPersister.writeElement(AbstractCollectionPersister.java:697)
at org.hibernate.persister.collection.AbstractCollectionPersister.insertRows(AbstractCollectionPersister.java:1192)
at org.hibernate.action.CollectionUpdateAction.execute(CollectionUpdateAction.java:56)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:243)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:227)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:143)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:296)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:877)
at de.bla.data.hibernate.DataSession.commitTransaction(DataSession.java:51)
... 40 more

Gumble · **Joined:** Mon Nov 28, 2005 12:07 pm **Posts:** 17

And derived from Entity:
Caused by: org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of de.bla.data.Entity.id
at org.hibernate.property.BasicPropertyAccessor$BasicGetter.get(BasicPropertyAccessor.java:171)

zzyborg · **Posted:** Wed Jan 18, 2006 12:04 pm

if everything is fine , it should give u result . plz check for any type mismatches in ur persistent class or mapping files . i've encountered such problems :)

Gumble · **Joined:** Mon Nov 28, 2005 12:07 pm **Posts:** 17

nothing is fine :(
And there are no typos because I have some other classes that are working in the same way. But this is the only 1-n relation (List-Implementation) - the n-1 relations are ok. Maybe the error is in the persisting code (simplified):

Code:

//retrieving saved 'Data' Object
Data data = session.getDataByName(crName);
//creating new 'Comment' Object
Comment comment = new Comment();
session.beginTransaction();
//adding the comment to the List
data.addComment(comment);
//saving the modified 'Data' Object
session.save(data);
session.commitTransactionAndClose();

I also tested with additional saving the 'Comment' Object:

Code:

session.save(comment);

but no success...

zzyborg · **Posted:** Wed Jan 18, 2006 11:05 pm

do u have a no argument constructor in your persistent class ?

as per api docs, you can get a PropertyAccessException due to

* failure of a security check
* an exception occurring inside the getter or setter method
* a nullable database column was mapped to a primitive-type property
* the Hibernate type was not castable to the property type (or vice-versa)

check for any of these