Discriminator column is missing from table when inheritance is used without
annotation
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Key: OPENJPA-670
URL: https://issues.apache.org/jira/browse/OPENJPA-670
Project: OpenJPA
Issue Type: Bug
Components: jdbc
Affects Versions: 1.2.0, 1.3.0
Reporter: Jeremy Bauer
According to the EJB 3.0 JPA spec (pp. 191, section 9.1.29):
"If the Inheritance annotation is not specified or if no inheritance type is
specified for an entity class
hierarchy, the SINGLE_TABLE mapping strategy is used."
I've found that if an entity inheritance hierarchy is specified without an
explicit DiscriminatorColumn or Inheritance annotation, a single table will be
used for mapping, but there will be no discriminator column in the table.
pp. 191 - 192, section 9.1.30 of the spec reads:
"For the SINGLE_TABLE mapping strategy, and typically also for the JOINED
strategy, the persistence
provider will use a type discriminator column."
and
"If the DiscriminatorColumn annotation is missing, and a discriminator column
is required, the
name of the discriminator column defaults to "DTYPE" and the discriminator type
to STRING."
Without a discriminator column a scenario such as:
entity B extends entity A
entity C extends entity A
"select c from C" will return entities of type A, B, and C (which is a data
integrity issue) because there is no way to distinguish between the entity
types.
The simple workaround is to specify an @Inheritance or @DiscriminatorColumn
annotation on the root class, but OpenJPA should exhibit default behavior
defined by the spec when these annotations are not specified.
I have a patch and jUnits in the works and will post them shortly.
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