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From Yuri <yde...@gmail.com>
Subject Re: Extend Mapping classes or implement custom strategies?
Date Wed, 19 Nov 2008 15:20:36 GMT

That makes me think whether using a custom VersionStrategy could be what I
need. Adding temporality to a persistent class does affect version and I
also see that StateManager already has a _version field  where I could store
a custom Version instance that holds for the validStart and validEnd. Here I
am assuming that VersionStrategy.map() can then synthetically add the
validEnd, validStart field mappings to ClassMapping and adjust primary key
and unique constraint.

Humm, I guess it would still make more sense to have a single @Temporal
annotation at the class level that would setup the ClassMapping,
FieldMappings and the proper version strategy otherwise the user would have
to declare a version field with a specific Version object.

I still need to figure out how to add a new custom annotation and override
the default strategies with temporal ones. Can ProductDerivation help in any
way here or should I stay away from it? I was gong the nuclear path of
extending ProductDerivation, Configuration, MappingRepository, ClassMapping,
etc, etc.

thanks for you help!

-- yuri


Pinaki Poddar wrote:
> 
> Hi,
>   An analogous usage is VersionStrategy.
>   May be you should also refer to Custom Field Mapping [1]
>   Adding extra temporal data to every instance is most likely can be
> accomplished by adding extra field mapping to an annotated class. So
> effectively the annotation should result in adding extra field mapping to
> ClassMapping. Then the user need not to declare fields for the temporal
> state.
> 
> [1]
> http://openjpa.apache.org/builds/latest/docs/manual/manual.html#ref_guide_mapping_custom_field
> 
> 
> 

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