[eclipselink-users] question about one-to-many

[Jan Kriesten <jan.kriesten@xxxxxxxxxxxx>]

Hi,

I've an understanding problem using one-to-many:

I've got the following tables:

REZ_REZEPTE:
id: int
name: String

REZ_ZUT:
id: int
rezid: int
name: String

Now I want to have a List of all REZ_ZUT in REZ_REZEPTE.

This actually works:

@Entity
@Table { val name = "REZ_REZEPTE" }
@serializable
class Rezept {
  @Id @GeneratedValue
  @BeanProperty var id: Int = _id
  @BeanProperty var name: String = _name
  @OneToMany { val cascade = Array( CascadeType.ALL ), val targetEntity =
classOf[Zutat], val mappedBy = "rezept" }
  @BeanProperty var zutaten: JList[Zutat] = null
}

But this needs class Zutat mapping back to 'Rezept'.

It should work to use

@OneToMany { val cascade = Array( CascadeType.ALL ), val targetEntity =
classOf[Zutat], val fetch=FetchType.EAGER }
  @JoinColumn { val name = "rezid" }
  @BeanProperty var zutaten: JList[Zutat] = null

but that give an error:

Internal Exception: Exception [EclipseLink-7160] (Eclipse Persistence Services -
1.0.1 (Build 20080905)): org.eclipse.persistence.exceptions.ValidationException
Exception Description: @OneToMany for attribute name [zutaten] in entity class
[class Rezept] should not have @JoinColumn(s) specified. In the case where the
@OneToMany is not mapped by another entity (that is, it is the owning side and
is uni-directional), it should specify (optional through defaulting) a @JoinTable.

I tried to use the xml-variant instead (which at least allows to define
join-columns):

   <entity class="Rezept">
     <attributes>
       <id name="id"><generated-value /></id>
       <one-to-many name="zutaten" target-entity="Zutat" fetch="EAGER">
         <join-column name="rezid"/>
       </one-to-many>
     </attributes>
   </entity>

But that gives a SQL-Exception - and I really don't know why EclipseLink is
trying to access a table named "rez_rezepte_rez_zut":

Exception [EclipseLink-4002] (Eclipse Persistence Services - 1.0.1 (Build
20080905)): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: Table
'rez_rezepte_rez_zut' doesn't exist
Error Code: 1146
Call: SELECT t1.ID, t1.EINHEIT, t1.MENGE_MAX, t1.MENGE_MIN, t1.MENGE_ORG,
t1.NAME, t1.REZID FROM REZ_REZEPTE_REZ_ZUT t0, REZ_ZUT t1 WHERE ((t0.Rezept_ID =
?) AND (t1.ID = t0.zutaten_ID))

Can someone give me some insight where I'm going wrong?

Best regards, --- Jan.