[hibernate-dev] Making it pluggable how GenerationType.AUTO is mapped

[Gunnar Morling]

Yes, it would be great to have this in ORM 5.0.

Currently, AUTO is a bit AWKWARD to use with MongoDB; if
USE_NEW_ID_GENERATOR_MAPPINGS is set to false, we map AUTO to IDENTITY (via
Dialect#getNativeIdentifierGeneratorClass()) which only works if the id
type is MongoDB's ObjectId type or a String marked with @Type("objectid").
And if USE_NEW_ID_GENERATOR_MAPPINGS is set to true, it will be mapped to
the sequence strategy (as per the logic in ORM). This in turn only works if
the id is of a numeric type.

So it's quite easy for the user to run into misconfigurations here.

I've filed https://hibernate.atlassian.net/browse/HHH-9524 to track this
requirement and catch the discussion.

Thanks,

--Gunnar


> 2014-12-01 18:25 GMT+01:00 Steve Ebersole <steve at hibernate.org>:
>
>> Maybe.  I'll have to look a little closer.  Is this something you are
>> looking at for use with ORM 5.0?
>>
>> On Fri, Nov 28, 2014 at 5:08 AM, Gunnar Morling <gunnar at hibernate.org>
>> wrote:
>>
>>> Hi Steve, all,
>>>
>>> For OGM it would be beneficial if there was an extension point in ORM
>>> which
>>> allows us to customize how GenerationType.AUTO is mapped. AFAICS, that's
>>> currently semi-hard coded in ORM. Depending on whether
>>> "new_generator_mappings" is set, either SEQUENCE (true) or "native"
>>> (false)
>>> will be used.
>>>
>>> Now for the MongoDB grid dialect we'd ideally do the following: If the id
>>> of an entity is declared as
>>>
>>>      org.bson.typesObjectId
>>>
>>> or
>>>
>>>      @Type(type = "objectid") String
>>>
>>> then map AUTO to IDENTITY (ObjectId is a MongoDB-specific type which
>>> resembles an identity column). Otherwise map it to TABLE (or SEQUENCE,
>>> which transparently falls back to TABLE).
>>>
>>> I.e. this decision would not be a global one, but depend on the specific
>>> id
>>> type.
>>>
>>> Would this be feasible to do? or is it mandated by JPA somehow that AUTO
>>> is
>>> always mapped in the same way? I cannot judge on the amount of changes
>>> required in ORM as atm. AUTO always is mapped in the same way, it doesn't
>>> depend on the specific entity and its id type.
>>>
>>> Any thoughts?
>>>
>>> Thanks,
>>>
>>> --Gunnar
>>> _______________________________________________
>>> hibernate-dev mailing list
>>> hibernate-dev at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>>
>>
>>
>