About relation

faq

Is ObjectDB better than Object Relational Mapping (ORM)?

As noted above, using ObjectDB instead of a relational database and ORM combination is easier and leads to better performance. ORM tools, however, are very useful where the use of a relational database is mandatory (e.g. as a result of a customer reques ...

 
faq

Can I use ObjectDB to access a relational database?

To access relational databases using the Java Persistence API (JPA) you will need an Object Relational Mapping (ORM) tool, such as Hibernate, TopLink, EclipseLink, Open JPA or DataNucleus. The DataNucleus ORM implementation supports also the Java Data O ...

 
manual

Comparison in JPQL and Criteria API

Explains how comparison operators can be used in JPQL queries, including in comparing null values. Most JPQL queries use at least one comparison operator in their WHERE clause. This page covers the following topics: Comparison Operators Comparing NULL values IS [NOT] NULL Comp ...

 
forum_thread

Object Relations Error after Schema Change

Hi we have a problem with relations in OBjectDB 2.4.6, the problem occured after we changed relations in few clases. Specificaly we deleted relation pointing to one class and created new relation to third class. If we restart both ObjectDB and Jboss everything works fine for a short period. Attached is a ObjectDB error message. Kind regards. ... we changed relations in few clases. Specificaly we deleted relation pointing to one class and created new relation to third class. If we restart both ObjectDB and Jboss ...

 
forum_thread

how to query by properties of onetomany relations? (Error 990)

the following code fails em.createQuery("select f from Foo f where f.bars.name = ?1", Foo.class).setParameter(1, barName) stacktrace: ... in my test database i have one Foo entity with one Bar relation   thanks in advanced ...

 
forum_thread

ObjectDB Explorer don't show ManyToOne relations

Hello support. we have a problem with the ObjectDB Explorer and @ManyToOne relations. We persist the entity FolderImpl that has an attribute of type ModelElement. If we use an interface for the attribute then the ObjectDB Explorer shows NULL for the attribute although our unit test checks that the attribute is not NULL in the database. @Entity public class ModelElementImpl implements ModelElement { ... } @Entity public class FolderImpl { #1 2015-03-24 07:54 Hello support. we have a problem with the ObjectDB Explorer and @ManyToOne relations. We persist ...

 
forum_thread

Entity is not related to ObjectDB, but i get exception from ObjectDB

Here is the description of the problem we are facing:
We have an entity DialogActionNew which previously was located in ObjectDB and recently has been transferred to PostreSQL. We are using ORM Hibernate
When getting this entity from PostgreSQL with the key EntityManager.find(id), we receive another entity - DialogNew, which has an exception: #1 2014-04-22 15:09 Here is the description of the problem we are facing:
We have an entity DialogActionNew which previously was loca ...

 
forum_thread

Error: Failed to write value of field X using reflection (oneToMany relation)

Hi there! I have been all day trying to solve this. I have read multiple sites and documentation, but I can go through this. I have a clase named Pedido, that have a reference ManyToOne to a clase Cliente. #1 2017-02-25 00:59 Hi there! I have been all day trying to solve this. I have read multiple sites and documentation, but I can go th ...

 
forum_thread

Lazy loading does not work - crud takes long

tomee7.0.0SNAPSHOT,objectdb 2.6.4 The OneToMany Entities are filled with 40.000 Records and they have between 20-40 Columns. It takes over 50s to load all Project Enities that contains the OneToMany Relationships. It should be load lazy but i didnt know why the query fetch all the Data. ... On the other side if i remove all items from the OneToMany Relation at Example Datapoint (10.000 Recors). The API need for 50 ... Advalm.java 1 oneToMany Relation to Advalm 2 oneToMany Relations to --> Advalm and ...

 
forum_thread

@Transient

Hello, I have a persistent class which looks something like this: @Entity public class Test { private String string; private Date date; @Transient private boolean test; // getters/setters } When I persist the class the transient 'boolean test' is stored in the database, maybe I am doing it wrong but I expect #1 2010-11-22 12:16 Hello, I have a persistent class which looks something like this: @ Entity public ...