About null

api-jpa

javax.persistence.criteria.From

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)

 
forum_thread

List of Enum Values in an entity

Hello, I'm new with ObjectDB and just tried out the example in the Eclipse/Glassfish tutorial (http://www.objectdb.com/tutorial/jpa/eclipse/ee). After testing was successful, I extended the Guest class with an ArrayList of Enums: private ArrayList<GuestFlag> flags; The flags are stored into the database without any problem. In the explorer I can see that it is stored as array of Strings. ... to load the flags from the database, the list is always null. What am I doing wrong? Joachim ... If the entity is enhanced, you may see a  null value in the debugger before accessing the field, but when the field is ...

 
api-jpa

javax.persistence.criteria.Predicate

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

 
forum_thread

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 ...

 
forum_thread

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 ( ) ; ...

 
doc

java.lang.RuntimeException

(Exception of java.langException RuntimeException)

 
forum_thread

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 ;   ...

 
forum_thread

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 ...

 
forum_thread

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 ...

 
api-jdo

javax.jdo.annotations.Persistent

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