tree « Query « JPA Q&A

1. OpenJPA 1.2.x select tree structure using JPQL stackoverflow.com

I'm using OpenJPA 1.2.x (JPA1). The problem is that I can't get on with querying tree structure using JPQL. Please, see my entity:

@NamedQueries(
         { ...

2. when select JPA tree, childNodes is always null stackoverflow.com

I'm trying to select tree structure using JPQL. Mapping works a bit different than I expected. It maps tree structure to parent but List childNodes is always null :( Here is ...

3. Merging tree-like structure in OpenJPA? stackoverflow.com

I am trying to build a composite tree-like structure using OpenJPA 2.1 consisting of these classes: Criterion - base, abstract class, SingleCriterion - actual tree leaf, CompositeCriterion - actual tree node

@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="dtype",discriminatorType=DiscriminatorType.STRING)
public abstract class Criterion ...

4. Tree select question forum.hibernate.org

I have a tree structure where I use a parent id . This is working very nicely. My object contains a list of children which are of the same object type. Now I wish to introduce more functionality where the tree will be created based on an external dependency. Lets say my object is a Lesson. Lessons can contain Lessons etc. ...

5. Tree-like structure (Table with self-association) forum.hibernate.org

6. Tree Based Query forum.hibernate.org

Hi all, I have a location entity that represents a tree of locations.. ie: world->north america->canada->toronto.. I also have an item entity that has a location many-to-one.. and i want to query for items who location is equal to or a child of.. ie: if item a is in location toronto.. I need to be able to query for items in ...

7. TransientObjectException in tree-like structure forum.hibernate.org

Hello I am playing around with Hibernate 2.1.4 since this week and struggling, at the moment with the following problem: My HSQLDB 1.7.2rc6 contains one table ENTRY and the corresponding class Entry should build a double-linked tree-like structure, means each Entry object has a parent and some children. After reading all entry objects and fill them up in a TreeModel, I ...

8. Tree Like Structure forum.hibernate.org

I have a Tree like structure where top node is attached to multiple sub-nodes through an association table(many-to-many relationship). This can go down upto 3-4 levels. I want to load the complete tree in one go. My problem is that even with 3-4 rows in one table, Hibernate issues 25-30 sqls. Utimately we will have few thousands of rows. Can you ...

9. Implementing Nested Set Model to handle Tree like structures forum.hibernate.org

Dear all I would like to implement the "Nested Set Model" using hibernate. The Nested step model has the advantage that it nicely allows us to map tree like strutures to the database. Some nice articles one the subject, are available at: http://www.sitepoint.com/print/hierarch ... a-database http://www.edutech.ch/contribution/nstrees/index.php http://threebit.net/tutorials/nestedset/tutorial1.html http://www.intelligententerprise.com/00 ... stid=60290 Does someone has implemented this? I an trying to find how ...

10. Implementing Nested Set Model to handle Tree like structures forum.hibernate.org

11. Sub tree selects forum.hibernate.org

Hibernate version:3.0 Name and version of the database you are using:MySQL Hi All, I have a simple mapping of a Category Table with a Product Table. A Category Table can have multiple sub categories. The Product Table has a FK reference to a Category. Category: ID NAME PARENT_ID ------------------------ 1 foo null 2 bar 1 3 acme 2 4 apple 3 ...

12. Tree like structure in a table forum.hibernate.org

Hi all am encoutering a challenage here how to u map a tree structure to a table? e.g public class Node{ Node parent; List child=new ArrayList();//Stores a list of child nodes } And all the data is mapped to a table so in order to find the root i probably have a node where the parent is null. How do i ...