About null



Represents a bound type, usually an entity that appears in the from clause, but may also be an embeddable belonging to an entity in the from clause.(Interface of JPA)



The type of a simple or compound predicate: a conjunction or disjunction of restrictions.(Interface of JPA)


Should derived fields of an EmbeddedId be manually maintained by app code?

If I have an Entity which has a primary key which is derived and I am implementing it using @EmbeddedId, am I responsible for maintaining the derived fields of the @EmbeddedId? I could not find anything in the JPA 2.0 spec http://download.oracle.com/auth/otn-pub/jcp/persistence-2.0-fr-oth-JSpec/persistence-2_0-final-spec.pdf?e=1317047713&h=54831c176e81a244a4c309e13eba0b27 which tells me what to expect. ... 1 , em ) ; if ( item == null ) { throw new TestException ( "cannot ... null com.objectdb.o.InternalException at com.objectdb.o.VUT.e(VUT.java:220) at ... , "1" ) ; if ( c == null ) { c = new EContainer ( ) ; ...


Optimistic locking: prevent version increment on entity collection attribute

Hello, I have an entity E with an attribute which is a collection of entities (one to many relationship) with an optimistic locking strategy supported by a version field. Is it possible to prevent the increment of the version of entity E when entities are added to or removed from the collection? Something like the equivalent of @OptimisticLock(excluded=true) in Hibernate? Thanks, Farid ... When I use it in my web app it fails; the collection is null! In the application (web app), I create the readings in one call ... readings) but when I try to get the collection of readings null is returned. I have tried to clear the entity manager in the ...


Possible issue for JPQL "LEFT [OUTER] JOIN"

Possible issue for JPQL "LEFT [OUTER] JOIN" is doing "[INNER] JOIN".   Thanks. ... "SELECT a,b FROM A a LEFT OUTER JOIN a.listB b WHERE b IS NULL" where the output would be [A4, null] or even throw an Exception instead [A3, null] [A4, null]??? NULL is ...



(Exception of java.langException RuntimeException)


Entity listener - event instead of object

Hi, Currently I'm playing with entity listener to implement auditing with difference between values in updated entity. There is a problem however with accessing "old" version of object stored in database. I can't find the nice way to use EntityManager in EntityListener. Because of that, I can't store separate entity for given event. Right now I'm using BaseEntity which contains ... ) ) ) : null ; final String entityName = event. getEntity ... ) ; Object oldPropValue = null ; Object newPropValue = null ;   ...


Doctor bug?

Please see the attached .odb file. It was freshly created by my web application, and just very few entries have been posted to the database yet. But still the doctor reports a whole bunch of errors. My application seems to function properly though. I guess this is a bug in the doctor? Using version 2.4.1. I get  ... 1 ] Unexpected exception in page #3 entry #0: null [ 2 ] Unexpected exception in page #3 entry #1: null [ 3 ] Unexpected exception in page #4 entry #0: null ...



Annotation for defining the persistence of a member.(Annotation of JDO)


Database Inconsistency or corruption

Hi, since a week I have been trying to find a solution to a strange problem. We are using ObjectDB 2.6.8_02 im embedded mode. The problem is that data gets lost when updating an entity. 1-) Background Consider Three entities: ObjectValue, Attribute and Value. ObjectValue has a one to many relationship to Attribute and Attribute has a one to one relationship to Value. ... Attribute  ID:=1400, Name:=profileName, Value:=ID:=null, PrimitiveValue:=ProfileName 99 (Just a test update...), REVISION:=1, ... test update...)" The id of the new Value object is null "Value:=ID:=null". This is the first strange thing. Because, after ...