AW: [OJB-developers] Using CollectionDescriptor in repository.xml

[Mahler T. <tho...@it...>]

Hi Leandro,

I'll try to explain the 1-n section from the tutorial3.
Say you have a class ProductGroup with a Vector attribute =
allArticlesInGroup
 that holds all Article objects belonging to this group.

That is: *one* ProductGroup holds *n* Articles.

You must tell OJB how to load the allArticlesInGroup attribute on =
loading a
ProductGroup object.
This is done by the following CollectionDescriptor:
<ClassDescriptor id=3D"2">
      <class.name>test.ojb.broker.ProductGroup</class.name>
	...
      <CollectionDescriptor id=3D"1">
         <cdfield.name>allArticlesInGroup</cdfield.name>
         <items.class>test.ojb.broker.Article</items.class>
         <inverse_fk_descriptor_ids>4</inverse_fk_descriptor_ids>
      </CollectionDescriptor>
	...

This descriptor contains the following info:
- The class ProductGroup has a container attribute allArticlesInGroup.=20
  The Java-type of this attribute is not declared. It maybe of type
SomeType[],=20
  Collection, or ManageableCollection.
- The Items in this Container are of type Article
- The Mapping of class Article has a attribute with id=3D"4" that holds =
a=20
  foreign key value idetifying the associated ProductGroup.

HTH,

Thomas

> -----Urspr=FCngliche Nachricht-----
> Von: Leandro Rodrigo Saad Cruz [mailto:le...@ib...]
> Gesendet: Freitag, 22. M=E4rz 2002 15:30
> An: obj...@li...
> Betreff: [OJB-developers] Using CollectionDescriptor in =
repository.xml
>=20
>=20
> Hi all. There is one thing I didn't understand from the docs about
> association mapping
> http://objectbridge.sourceforge.net/tutorial3.html#1-n
>=20
> <CollectionDescriptor id=3D"1">
>    <cdfield.name>collection</cdfield.name>=20
>    ******* -> does this field must be present in repository.xml in
> SomeCLASS ClassDescriptor ? or just be a field in SomeCLASS impl ?
>=20
>    <items.class>SomeCLASS</items.class>
>    <inverse_fk_descriptor_ids>2</inverse_fk_descriptor_ids>
> </CollectionDescriptor>
>=20
> I keep getting exceptions like this :
> Expcetion : java.util.NoSuchElementException
> StackTrace: java.util.NoSuchElementException at
> ojb.broker.accesslayer.RsIterator.next(RsIterator.java) at
> ojb.broker.singlevm.PersistenceBrokerImpl.getCollectionByQuery
> (PersistenceBrokerImpl.java:931)at=20
> ojb.broker.singlevm.PersistenceBrokerImpl.getCollectionByQuery
> (PersistenceBrokerImpl.java:1000)at=20
> ojb.broker.singlevm.PersistenceBrokerImpl.getCollectionByQuery
> (PersistenceBrokerImpl.java:1093)at=20
> ojb.broker.singlevm.PersistenceBrokerImpl.getCollectionByQuery
> (PersistenceBrokerImpl.java:1080)at
> ....
>=20
> that doesn't help me so much.
>=20
>=20
> --=20
> Leandro Rodrigo Saad Cruz
> IT - Inter Business Tecnologia e Servicos (IB)
> http://www.ibnetwork.com.br
>=20
>=20
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>=20