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From Jakob Braeuchi <jbraeu...@gmx.ch>
Subject Re: mixed mapping (1 table/1 class, 1 table/many)
Date Sat, 10 Jul 2004 16:32:13 GMT
hi thomas,

i know of andrew's problems and the configurable ojbConcreteClass. but i'd 
prefer to take the baby steps ;)

jakob

Thomas Dudziak wrote:
> Jakob Braeuchi wrote:
> 
>> hi all,
>>
>> i'm currently working on support for mixed-mapping within a class 
>> hierarchy.
>> it's now possible to use 1 table/1 class and 1 table/many classes 
>> (ojbConcreteClass) within the class hierarchy.
>> the implementation is still based on adding additional criteria for 
>> ojbConcreteClass to a copy of the query, but it's done dynamically 
>> when processing all concrete extents.
>>
>> i was also thinking of a query wrapper to transport ojbConcreteClass 
>> so i do not have to copy the query and manipulation the criteria. this 
>> solution would require some refactoring of the jdbc/sql part of ojb.
> 
> 
> There are at least two problems with ojbConcreteClass and queries that I 
> know of, perhaps you could have a look at them while you're at it ?
> 
> * Queries seem to not respect inheritance hierarchies that use the 
> multiple-joined-tables strategy (which requires that no extent-class is 
> used, and ojbConcreteClass is useless in this scenario), see this thread:
> 
> http://nagoya.apache.org/eyebrowse/BrowseList?listName=ojb-user@db.apache.org&by=thread&from=819109

> 
> 
> * If you remember we had a discussion last month with Andrew Clute about 
> the possibility to specify something like ojbConcreteClass on the other 
> end of a reference/collection:
> 
> http://nagoya.apache.org/eyebrowse/BrowseList?listName=ojb-user@db.apache.org&by=thread&from=766552

> 
> 
> 
> Also it would be nice to make the name of the concrete-class field 
> configurable.
> 
> I don't know how much additional work that would mean, though ;-)
> 
> Tom
> 
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