Talk:EclipseLink/Development/JPA2.0/Extended Map support

Gordon Yorke 13:28, 30 July 2008 (EDT):

• In General
  • The use case where the key is mapped in the target object falls under the existing @MapKey support. Unless the key is mapped in both the Map mapping and the target class in which case we should raise a 'multiple writable mappings' exception.
  • The Unidirectional OneToMany mapping without join table must also be supported.

• Embeddable to Embeddable where the same embeddable the default would be to create a duplicate set of columns.
  • Only if the user mapped the two Embeddables to the same columns using attribute overrides would the key and value share same data. Also check for multiple writable mappings in this case.

• JoinTable no Key is not a supported usecase in the specification. May be more difficult to implement.

• Entity - Basic, "Collection table contains foreign keys to the source and foreign keys to the key. Value is a field on the key"
  • This is not supported by the specification
  • In this case the Collection Table is just a Join Table

• Entity - Embeddable, "Collection table contains foreign keys to the source and foreign keys to the key. The value is Embedded in the Key"
  • This is not supported by the specification.
  • In this case the Collection Table is just a Join Table

• Entity - Entity
  • may not be a join table as OneToMany's are supported.

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